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Biomedical subjects

M J Miller

Publications and source records attributed to M J Miller.

At least 73 records · Page 4Linked to original sources
PubMed2000

Free filet extremity flap: indications and options for reconstruction.

Radical and extended forequarter and hind limb amputations have been used for curative and palliative intents. Concerns regarding wound healing and closure, especially in irradiated fields, have occasionally limited the extent of ablation. This article reports an experience with coverage of these large defects by using the free filet extremity flap. A retrospective review was performed of 11 patients who had undergone immediate reconstruction with free filet extremity flaps between 1991 and 1998. There were nine men and two women with an average age of 43.9 years. All except three patients received preoperative radiotherapy. Resections included four hindquarter and seven forequarter amputations for palliation of intractable pain, tissue necrosis, and infections. Donor vessels included the brachial artery, its venae comitantes, cephalic and basilic veins, and common femoral and popliteal vessels. Immediate reconstruction was successful in all cases by the use of the amputated limb as the free filet flap. All wounds healed despite irradiation inclusive of defects up to 50 cm x 70 cm (3500 cm2). The average follow-up time was 5 months with a mean survival of 3.5 months. Four patients currently are alive, and one patient died within 30 days of surgery. The remaining six patients have died of their disease within 9 months of the palliative procedures. Pain, tissue necrosis, and infections were improved in all patients after hospital discharge. Extensive defects can be reconstructed and healed successfully, even in irradiated wounds, with the use of the free filet extremity flap. Appropriate advanced preoperative and intraoperative planning is essential. Although survival was unchanged, this technique allowed healed wounds with an improvement in the quality of life.

Adult↗
PubMed2000

Effect of obesity on flap and donor-site complications in free transverse rectus abdominis myocutaneous flap breast reconstruction.

The purpose of this study was to assess the effect of obesity on flap and donor-site complications in patients undergoing free transverse rectus abdominis myocutaneous (TRAM) flap breast reconstruction. All patients undergoing breast reconstruction with free TRAM flaps at our institution from February 1, 1989, through May 31, 1998, were reviewed. Patients were divided into three groups based on their body mass index: normal (body mass index <25), overweight (body mass index 25 to 29), obese (body mass index > or =30). Flap and donor-site complications in the three groups were compared. A total of 936 breast reconstructions with free TRAM flaps were performed in 718 patients. There were 442 (61.6 percent) normal-weight, 212 (29.5 percent) overweight, and 64 (8.9 percent) obese patients. Flap complications occurred in 222 of 936 flaps (23.7 percent). Compared with normal-weight patients, obese patients had a significantly higher rate of overall flap complications (39.1 versus 20.4 percent; p = 0.001), total flap loss (3.2 versus 0 percent; p = 0.001), flap seroma (10.9 versus 3.2 percent; p = 0.004), and mastectomy flap necrosis (21.9 versus 6.6 percent; p = 0.001). Similarly, overweight patients had a significantly higher rate of overall flap complications (27.8 versus 20.4 percent; p = 0.033), total flap loss (1.9 versus 0 percent p = 0.004), flap hematoma (0 versus 3.2 percent; p = 0.007), and mastectomy flap necrosis (15.1 versus 6.6 percent; p = 0.001) compared with normal-weight patients. Donor-site complications occurred in 106 of 718 patients (14.8 percent). Compared with normal-weight patients, obese patients had a significantly higher rate of overall donor-site complications (23.4 versus 11.1 percent; p = 0.005), infection (4.7 versus 0.5 percent; p = 0.016), seroma (9.4 versus 0.9 percent; p <0.001), and hernia (6.3 versus 1.6 percent; p = 0.039). Similarly, overweight patients had a significantly higher rate of overall donor-site complications (19.8 versus 11.1 percent; p = 0.003), infection (2.4 versus 0.5 percent; p = 0.039), bulge (5.2 versus 1.8 percent; p = 0.016), and hernia (4.3 versus 1.6 percent; p = 0.039) compared with normal-weight patients. There were no significant differences in age distribution, smoking history, or comorbid conditions among the three groups of patients. Obese patients, however, had a significantly higher incidence of preoperative radiotherapy and preoperative chemotherapy than did patients in the other two groups. A total of 23.4 percent of obese patients had preoperative radiation therapy compared with 12.3 percent of overweight patients and 12.4 percent of normal-weight patients; 34.4 percent of obese patients had preoperative chemotherapy compared with 24.5 percent of overweight patients and 17.7 percent of normal-weight patients. Multiple logistic regression analysis was used to determine the risk factors for flap and donor-site complications while simultaneously controlling for potential confounding factors, including the incidence of preoperative chemotherapy and radiotherapy. In summary, obese and overweight patients undergoing breast reconstruction with free TRAM flaps had significantly higher total flap loss, flap hematoma, flap seroma, mastectomy skin flap necrosis, donor-site infection, donor-site seroma, and hernia compared with normal-weight patients. There were no significant differences in the rate of partial flap loss, vessel thrombosis, fat necrosis, abdominal flap necrosis, or umbilical necrosis between any of the groups. The majority of overweight and even obese patients who undertake breast reconstruction with free TRAM flaps complete the reconstruction successfully. Both such patients and surgeons, however, must clearly understand that the risk of failure and complications is higher than in normal-weight patients. Patients who are morbidly obese are at very high risk of failure and complications and should avoid any type of TRAM flap breast reconstruction.

Adult↗
PubMed2000

Effect of smoking on complications in patients undergoing free TRAM flap breast reconstruction.

Free pedicled transverse rectus abdominis myocutaneous (TRAM) flap breast reconstruction is often advocated as the procedure of choice for autogenous tissue breast reconstruction in high-risk patients, such as smokers. However, whether use of the free TRAM flap is a desirable option for breast reconstruction in smokers is still unclear. All patients undergoing breast reconstruction with free TRAM flaps at our institution between February of 1989 and May of 1998 were reviewed. Patients were classified as smokers, former smokers (patients who had stopped smoking at least 4 weeks before surgery), and nonsmokers. Flap and donor-site complications in the three groups were compared. Information on demographic characteristics, body mass index, and comorbid medical conditions was used to perform multivariate statistical analysis. A total of 936 breast reconstructions with free TRAM flaps were performed in 718 patients (80.9 percent immediate; 23.3 percent bilateral). There were 478 nonsmokers, 150 former smokers, and 90 smokers. Flap complications occurred in 222 (23.7 percent) of 936 flaps. Smokers had a higher incidence of mastectomy flap necrosis than nonsmokers (18.9 percent versus 9.0 percent; p = 0.005). Smokers who underwent immediate reconstruction had a significantly higher incidence of mastectomy skin flap necrosis than did smokers who underwent delayed reconstruction (21.7 percent versus 0 percent; p = 0.039). Donor-site complications occurred in 106 (14.8 percent) of 718 patients. Donor-site complications were more common in smokers than in former smokers (25.6 percent versus 10.0 percent; p = 0.001) or nonsmokers (25.6 percent versus 14.2 percent; p = 0.007). Compared with nonsmokers, smokers had significantly higher rates of abdominal flap necrosis (4.4 percent versus 0.8 percent; p = 0.025) and hernia (6.7 percent versus 2.1 percent; p = 0.016). No significant difference in complication rates was noted between former smokers and nonsmokers. Among smokers, patients with a smoking history of greater than 10 pack-years had a significantly higher overall complication rate compared with patients with a smoking history of 10 or fewer pack-years (55.8 percent versus 23.8 percent; p = 0.049). In summary, free TRAM flap breast reconstruction in smokers was not associated with a significant increase in the rates of vessel thrombosis, flap loss, or fat necrosis compared with rates in nonsmokers. However, smokers were at significantly higher risk for mastectomy skin flap necrosis, abdominal flap necrosis, and hernia compared with nonsmokers. Patients with a smoking history of greater than 10 pack-years were at especially high risk for perioperative complications, suggesting that this should be considered a relative contraindication for free TRAM flap breast reconstruction. Smoking-related complications were significantly reduced when the reconstruction was delayed or when the patient stopped smoking at least 4 weeks before surgery.

Adult↗
PubMed2000

Reconstruction of large sacral defects following total sacrectomy.

Total sacrectomies for cancer ablation often result in extensive defects that are challenging to reconstruct. In an effort to elucidate the criteria to select the most effective reconstructive options, we reviewed our experience with the management of large sacral wound defects. All patients who had a sacral defect reconstruction after a total sacrectomy at our institution between January of 1993 and August of 1998 were reviewed. The size of the defect, the type of reconstruction, postoperative complications, and functional outcome in each patient were assessed. A total of 27 flaps were performed in 25 patients for sacral defect reconstruction after a total sacrectomy. Diagnoses consisted of chordoma (n = 13), giant cell carcinoma (n = 2), sarcoma (n = 5), rectal adenocarcinoma (n = 4), and radiation induced necrosis (n = 1). The size of sacral defects ranged from 18 to 450 cm2 (mean, 189.8 cm2). Ten patients, including five who had preoperative radiation therapy, underwent transpelvic vertical rectus abdominis myocutaneous (VRAM) flap reconstruction for sacral defects with a mean size of 203.3 cm2. Of these, five patients (50 percent) had complications (four minor wound dehiscences and one seroma). Eight patients, including one who had preoperative radiation therapy, underwent bilateral gluteal advancement flap reconstruction for sacral defects with a mean size of 198.0 cm2. They had no complications. Two patients, both of whom had preoperative radiation therapy, underwent gluteal rotation flap reconstruction for sacral defects of 120 cm2 and 144 cm2. Both patients had complications (one partial flap loss and one nonhealing wound requiring a free flap). Three patients, including one who had preoperative radiation therapy, underwent reconstruction with combined gluteal and posterior thigh flaps for sacral defects with a mean size of 246 cm2; two of these patients had partial necrosis of the posterior thigh flaps. Three patients, all of whom had preoperative radiation therapy, underwent free flap reconstruction for sacral defects with a mean size of 144.3 cm2. They had no complications. Our experience suggests that there are three reliable options for the reconstruction of large sacral wound defects: bilateral gluteal advancement flaps, transpelvic rectus myocutaneous flaps, and free flaps. In patients with no preoperative radiation therapy and intact gluteal vessels, the use of bilateral gluteal advancement flaps should be considered. In patients with a history of radiation to the sacral area and in patients whose gluteal vessels have been damaged, the use of the transpelvic VRAM flap should be considered. If the transpelvic VRAM flap cannot be used because of previous abdominal surgery, a free flap should be considered as a last option.

Adult↗
PubMed2000

Postoperative adjuvant irradiation: effects on tranverse rectus abdominis muscle flap breast reconstruction.

The use of postoperative irradiation following oncologic breast surgery is dictated by tumor pathology, margins, and lymph node involvement. Although irradiation negatively influences implant reconstruction, it is less clear what effect it has on autogenous tissue. This study evaluated the effect of postoperative irradiation on transverse rectus abdominis muscle (TRAM) flap breast reconstruction. A retrospective review was performed on all patients undergoing immediate TRAM flap breast reconstruction followed by postoperative irradiation between 1988 and 1998. Forty-one patients with a median age of 48 years received an average of 50.99 Gy of fractionated irradiation within 6 months after breast reconstruction. All except two received adjuvant chemotherapy. Data were obtained from personal communication, physical examination, chart, and photographic review. The minimum follow-up time was 1 year, with an average of 3 years, after completion of radiation therapy. Nine patients received pedicled TRAM flaps and 32 received reconstruction with microvascular transfer. Fourteen patients had bilateral reconstruction, but irradiation was administered unilaterally to the breast with the higher risk of local recurrence. The remaining 27 patients had unilateral reconstruction. All patients were examined at least 1 year after radiotherapy. No flap loss occurred, but 10 patients (24 percent) required an additional flap to correct flap contracture. Nine patients (22 percent) maintained a normal breast volume. Hyperpigmentation occurred in 37 percent of the patients, and 56 percent were noted to have a firm reconstruction. Palpable fat necrosis was noted in 34 percent of the flaps and loss of symmetry in 78 percent. Because the numbers were small, there was no statistical difference between the pedicled and free TRAM group. However, as a group, the findings were statistically significant when compared with 1,443 nonirradiated TRAM patients. Despite the success of flap transfer, unpredictable volume, contour, and symmetry loss make it difficult to achieve consistent results using immediate TRAM breast reconstruction with postoperative irradiation. TRAM flap reconstruction in this setting should be approached cautiously, and delayed reconstruction in selected patients should be considered. Patients should be aware that multiple revisions and, possibly, additional flaps are necessary to correct the progressive deformity from radiation therapy.

Adult↗
PubMed2000

Treatment of gastric ulcers and diarrhea with the Amazonian herbal medicine sangre de grado.

Sangre de grado is an Amazonian herbal medicine used to facilitate the healing of gastric ulcers and to treat gastritis, diarrhea, skin lesions, and insect stings. This study was designed to evaluate the gastrointestinal applications. Gastric ulcers were induced in rats by brief serosal exposure of the fundus to acetic acid (80%). Sangre de grado was administered in drinking water at 1:1,000 and 1:10,000 dilutions from the postoperative period to day 7. Guinea pig ileum secretory responses to capsaicin, electrical field stimulation, and the neurokinin-1 (NK-1) agonist [Sar(9),Met(O(2))(11)]substance P were examined in Ussing chambers. Sangre de grado facilitated the healing of experimental gastric ulcer, reducing myeloperoxidase activity, ulcer size, and bacterial content of the ulcer. The expression of proinflammatory genes tumor necrosis factor-alpha, inducible nitric oxide synthase (iNOS), interleukin (IL)-1beta, IL-6, and cyclooxygenase-2 was upregulated by ulcer induction but reduced by sangre de grado treatment, particularly iNOS and IL-6. In Ussing chambers, sangre de grado impaired the secretory response to capsaicin but not to electrical field stimulation or the NK-1 agonist. We conclude that sangre de grado is a potent, cost-effective treatment for gastrointestinal ulcers and distress via antimicrobial, anti-inflammatory, and sensory afferent-dependent actions.

Animals↗
PubMed2000

Coexpression of receptors for adrenomedullin, calcitonin gene-related peptide, and amylin in pancreatic beta-cells.

Three receptors have been characterized by their ability to bind adrenomedullin (AM): L1, RDC1, and CRLR. Immunohistochemical analysis and RT-PCR showed that all three receptors are expressed by the insulin-producing cells of the islets of Langerhans. RDC1 and CRLR in the presence of particular modifying proteins can also bind calcitonin gene-related peptide (CGRP). Such data suggest that the inhibitory effect caused by both AM and CGRP on insulin secretion is mediated by a direct interaction with the beta-cell. We also identified receptors for amylin, the third member of the AM peptide family, in mouse insulin-secreting cells. The beta-cells located closer to the periphery of the islets had a stronger immunoreactivity for the AM/ CGRP receptors. This observation could be related to a paracrine mechanism, given the proximity of AM- and CGRP-secreting cells (F and delta-cells, respectively), which are located at the periphery of the islets. Interestingly, the smooth muscle cells in the pancreatic vasculature expressed only RDC1, which is in agreement with physiological data showing that AM functions in the cardiovascular system are mainly mediated through a CGRP1 receptor. These data further implicate AM and the other components of its peptide family as important regulators of insulin release.

Amino Acid Sequence↗
PubMed2000

Ecology of Borrelia burgdorferi in ticks (Acari: Ixodidae), rodents, and birds in the Sierra Nevada foothills, Placer County, California.

This study examined the prevalence of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner in host-seeking adult and nymphal Ixodes pacificus Cooley & Kohls and estimated the I. pacificus infestation and B. burgdorferi infection of rodent and avian hosts in the western Sierra Nevada foothills of northern California. Additionally, we identified species likely to participate in an enzootic cycle for B. burgdorferi in this yellow pine transition habitat. Evidence of infection with B. burgdorferi was identified in 7.3 and 5.4% of host-seeking I. pacificus adults and nymphs, respectively. Mean numbers of I. pacificus observed on rodents were 1.15 for Neotoma fuscipes Baird and 0.18 for Peromyscus spp. One of 104 ear punch tissues obtained from woodrats and none from 49 Peromyscus spp. yielded B. burgdorferi. A total of 291 collected birds representing 34 species had a mean of 0.27 I. pacificus per bird. The mean I. pacificus infestation of ground-dwelling birds was 2.5 ticks per bird. Forty-nine of 92 (53%) blood smears collected from birds were reactive to a B. burgdorferi specific antibody. This study presents the identification of a B. burgdorferi-like spirochete in birds in western North America. The tick burden and spirochete infection of birds suggests that birds may be involved in a local B. burgdorferi enzootic cycle and likely participate in the transport of ticks and spirochetes to other locations while rodents from this site do not appear to be major contributors.

Animals↗
PubMed2000

Studies and syntheses of siderophores, microbial iron chelators, and analogs as potential drug delivery agents.

Siderophores (microbial iron chelators) play an extremely important role in microbial pathogenicity. Microbial uptake of siderophore-iron complexes through active transport systems allow microbes to survive and proliferate even under iron deficient environments during invasion of a host. Due to their structural complexity, unique iron (III) chelation, acquisition properties, and their therapeutic potential, siderophores have attracted much attention in a broad range of disciplines. Tremendous progress has been made in siderophore syntheses, in determination of the structures and functions of outer membrane receptors (e.g. FhuA and FepA), and in the mechanistic insight into siderophore-iron-mediated active transport processes. One of the important practical applications of this active transport system is development of species-selective active drug transport (the Trojan Horse approach) to potentially treat infections due to drug resistant strains of microbes. Siderophore-drug conjugates have shown great potential in active drug delivery to target pathogenic microbes.

Drug Carriers↗
PubMed2000

Induction of heat shock protein 72 protects against organ damage in essential hypertension: A hypothesis.

Over 12 consecutive years, hyperthermia was induced by immersion in hot baths 1576 times in one subject with a long history of labile hypertension. In year 13 (1996), following hyperthermia induction, peripheral lymphocytes were analyzed by Western blot analysis for heat shock protein 72 (HSP72) gene expression. It was demonstrated that rectal and oral fevers maintained for 15 mins at 38.2 C and 38. 6 C or higher, respectively, triggered HSP72 expression. Because this subject showed no evidence of organ damage secondary to hypertension, and because both hyperthermia and acute hypertension upregulate HSP72 expression, a role for HSP72 in protection against the adverse effects of essential hypertension disease is proposed and discussed.

Blotting, Western↗
PubMed1999

Inhibition of the broad spectrum nonmetallocarbapenamase of class A (NMC-A) beta-lactamase from Enterobacter cloacae by monocyclic beta-lactams.

beta-Lactamases hydrolyze beta-lactam antibiotics, a reaction that destroys their antibacterial activity. These enzymes, of which four classes are known, are the primary cause of resistance to beta-lactam antibiotics. The class A beta-lactamases form the largest group. A novel class A beta-lactamase, named the nonmetallocarbapenamase of class A (NMC-A) beta-lactamase, has been discovered recently that has a broad substrate profile that included carbapenem antibiotics. This is a serious development, since carbapenems have been relatively immune to the action of these resistance enzymes. Inhibitors for this enzyme are sought. We describe herein that a type of monobactam molecule of our design inactivates the NMC-A beta-lactamase rapidly, efficiently, and irreversibly. The mechanism of inactivation was investigated by solving the x-ray structure of the inhibited NMC-A enzyme to 1.95 A resolution. The structure shed light on the nature of the fragmentation of the inhibitor on enzyme acylation and indicated that there are two acyl-enzyme species that account for enzyme inhibition. Each of these inhibited enzyme species is trapped in a distinct local energy minimum that does not predispose the inhibitor species for deacylation, accounting for the irreversible mode of enzyme inhibition. Molecular dynamics simulations provided evidence in favor of a dynamic motion for the acyl-enzyme species, which samples a considerable conformational space prior to the entrapment of the two stable acyl-enzyme species in the local energy minima. A discussion of the likelihood of such dynamic motion for turnover of substrates during the normal catalytic processes of the enzyme is presented.

Anti-Bacterial Agents↗
PubMed1999

Possible preferential metabolism of xylene isomers following occupational exposure to mixed xylenes.

OBJECTIVES: Solvent exposures commonly involve mixtures of substances or mixtures of isomers of a single solvent. These may be metabolised through common pathways, resulting in the potential for metabolic interactions. These may then lead to accumulation of solvent or metabolic intermediates, some of which may be toxic. This paper describes a pilot study conducted to determine the correlation between airborne xylene isomers and the appearance of methylhippuric acid (MHA) isomers in urine of workers exposed mainly to xylene. The project also aimed to determine whether there is preferential metabolism of any isomer by comparison of the ratios of airborne isomers with the ratios of metabolite isomers appearing in urine. SUBJECTS AND METHODS: A total of 12 workers (11 male, 1 female) were recruited into this study, with 2 of the participants providing samples on more than one occasion. Workers included flooring contractors (5), printers (2), chemical manufacturers (2), histology technicians (2) and one householder using a xylene-based varnish. Subjects were aged between 24 and 48 years (37.6+/-2.0 years; mean +/- SEM). After giving informed consent, workers provided a prework and postwork urine sample on a midweek work day. Samples were stored frozen prior to analysis. Breathing-zone air samples were collected using personal air samplers at 50 ml/min. Solvents were trapped on activated-charcoal sampling tubes. Subjects wore pumps for 18-304 (178+/-24) min on the same day on which urine samples were collected. RESULTS: Xylene exposures ranged from 1.6 to over 7000 ppm. In all, 7 of 16 measurements exceeded the Australian TWA standard of 80 ppm. Two of the flooring contractors wore respiratory protective equipment (RPE) and the two histopathology technicians used workplace ventilation systems. Total urinary MHA output ranged from 10 to 8000 mmol/mol creatinine, with 6 of 16 samples exceeding the modified biological exposure index of 702 mmol/mol. Correlations between airborne concentrations of individual xylene isomers and their corresponding MHA isomers were poor but improved when workers using RPE were excluded from the analysis. Gradients of the regression lines (millimoles of MHA per mole of creatinine per parts per million of xylene) were 3.2 for o-isomers, 7.0 for p-isomers, and 14.4 for m-isomers. Comparisons of isomer ratios of xylene in air were made with the corresponding ratio of MHA isomers in urine. These revealed higher ratios of m-MHA to other MHA isomers than those of m-xylene to the other xylene isomers. The MHA isomer ratios were expected to be the same as the airborne xylene isomer ratios if there were no preferential elimination of any isomer. m-MHA appeared in urine in a greater proportion than would be predicted from the proportion of m-xylene detected in air. The time course of the appearance of MHA isomers in urine also suggests that interactions were taking place, with m-MHA appearing in high proportion in urine following several days of repeated heavy xylene exposure. On a single moderate exposure, m-MHA appeared initially in high proportion in the first few hours but was undetectable in urine after 18 h. p-MHA was detectable for up to 6 h after exposure, and o-MHA remained detectable after 18 h. CONCLUSIONS: This study suggests that excretion of m-MHA in urine is favoured over that of the other isomers following exposure to mixed xylenes. This is independent of airborne xylene isomer composition and suggests that the metabolism of m-xylene occurs preferentially to that of the other isomers. It is not clear at which step in the metabolism of xylene this preference occurs, although other work indicates that the initial oxidation of xylene to methylbenzyl alcohol by cytochrome P450 2E1 occurs at the same rate for each isomer. These findings suggest that there is potential for metabolic interactions between xylene isomers and that these may be the basis for xylene toxicity.

Adult↗
PubMed1999

Guided tissue fabrication from periosteum using preformed biodegradable polymer scaffolds.

A successful tissue engineering method for bone replacement would imitate natural bone graft by providing the essential elements for new bone formation using synthetic scaffolds, osteogenic cell populations, and bone induction factors. This is a study of the suitability of various formulations of poly(DL-lactic-co-glycolic acid) (PLGA) foams to provide a tissue conducting scaffold in an ovine model for bone flap fabrication. Three formulations were used of different copolymer ratio and molecular weight. Porous wafers of PLGA were stacked into rectangular chambers (volume 4 cm3) enclosed on five sides. Some chambers also contained autologous morcellized bone graft (MBG). The chambers were inserted with the open face adjacent to the cambium layer of the periosteum in rib beds of seven sheep and harvested after 8 weeks in vivo. Gross and histologic examination of the resulting tissue specimens demonstrated molded units of vascularized tissue generally conforming to the shape of the chambers and firmly attached to the periosteum. Polymer degradation appeared to occur by varying degrees based on polymer formulation. New bone formation was observed only in areas containing MBG. There was no evidence of significant inflammatory reaction or local tissue damage at 8 weeks. We conclude that a PLGA foam scaffold is (1) an efficient conductor of new tissue growth but not osteoinductive, (2) contributes to the shape of molded tissue, and (3) biocompatible when used in this model. Further studies are warranted to develop practical methods to deliver bone induction factors to the system to promote osseous tissue generation throughout the synthetic scaffold.

Absorbable Implants↗
PubMed1999

Quantitative cytomegalovirus DNA level in the blood and its relationship to cytomegalovirus retinitis in patients with acquired immune deficiency syndrome.

OBJECTIVE: A pilot study was performed to determine whether relationships exist between changes in a quantitative solution hybridization assay for cytomegalovirus (CMV) DNA in the blood and development of CMV retinitis, development of nonocular CMV disease, or reactivation of pre-existing CMV retinitis lesions. DESIGN: Observational case series. PARTICIPANTS: Two groups of human immunodeficiency virus-infected patients: 10 CMV antibody-positive patients with CD4+ T-lymphocyte counts of less than 50 ml and no CMV disease at baseline and 11 patients with CMV retinitis but no extraocular CMV disease at baseline. INTERVENTION: Quantitative changes in leukocyte-associated CMV DNA levels were observed over time. Anti-CMV therapies were based on clinical findings only. MAIN OUTCOME MEASURES: Development of CMV end-organ disease or change in activity of pre-existing CMV retinitis lesions was measured. RESULTS: Among patients with no CMV disease at baseline, four had CMV disease develop during follow-up (three cases of CMV retinitis, one case of presumed CMV esophagitis); all had CMV DNA levels greater than 5000 genomes/ml before the onset of CMV disease. The remaining six patients had levels less than 5000 genomes/ml throughout follow-up (P = 0.05). Among patients with CMV retinitis at baseline, all whose CMV DNA blood levels rose more than tenfold had extraocular CMV disease or reactivation of CMV retinitis develop. Raised CMV DNA blood levels were not seen in every patient with clinical reactivation of CMV retinitis. CONCLUSION: Elevated or rising CMV DNA blood levels appear to be associated with the development of CMV disease in individuals with low CD4+ T-lymphocyte counts. In patients with CMV retinitis, rising levels appear to be associated with the development of extraocular CMV disease or reactivation of CMV retinitis. Conversely, reactivation of CMV retinitis also may occur in the absence of changes in CMV DNA blood levels. Further studies are warranted to determine whether changes in CMV blood levels can be used as a guide for preemptive therapy to prevent reactivation of CMV retinitis lesions or to help choose between local and systemic therapy for management of reactivations.

AIDS-Related Opportunistic Infections↗
PubMed1999

Autocrine growth loops dependent on peptidyl alpha-amidating enzyme as targets for novel tumor cell growth inhibitors.

Many small cell lung tumors are dependent in vitro and in vivo on autocrine growth loops. The prototypical small cell lung cancer autocrine growth factor, gastrin-releasing peptide (GRP), is one of many peptide hormones which require post-translational carboxy-terminal alpha-amidation for bioactivity. We have reported that neuroendocrine human lung tumor cell lines express the bifunctional enzyme PAM which catalyzes the biosynthesis of alpha-amidated peptides in a two-step process, and have recently shown that non-small cell lung cancer cell lines and tumors, generally considered to be non-endocrine in nature, also express PAM. We have also shown that two chemical classes of PAM inhibitors, substrate analogues and specific copper chelators, inhibit amidating enzyme activity in cell-free extracts. Here we demonstrate in vitro growth inhibition of lung cancer tumor cell lines by both these classes of PAM inhibitors using the MTT assay and the clonogenic assay. Growth inhibition in a small cell lung cancer cell line can be overcome by exogenous addition of synthetic alpha-amidated GRP. Similar growth-suppressive effects are seen in cell lines stably transfected with a vector expressing antisense PAM RNA. These data support the mechanism of inhibition for a new type of chemotherapeutic/intervention agent, directed at synthesis and activation of peptide growth factors, and support our postulate that alpha-amidated peptide hormones are a common component in lung tumor autocrine growth biology which can be inhibited by targeting the biochemical mechanisms necessary for growth factor synthesis.

Anti-Bacterial Agents↗
PubMed1999

Syntheses and studies of multiwarhead siderophore-5-fluorouridine conjugates.

Siderophores are microbial iron chelating agents that sequester physiologically essential iron for microbes. Conjugation of drugs to siderophores allows use of active iron transport for microbially directed drug delivery. Syntheses and biological studies are described of the first multidrug isocyanurate-based siderophore analogues separately containing one, two, and three 5-fluorouridine (5-FU) derivatives as the drug component. The results indicate that a single siderophore can be used to deliver multiple drugs to target pathogenic microorganisms.

Anti-Bacterial Agents↗
PubMed1999

Loxosceles spider venom induces the production of alpha and beta chemokines: implications for the pathogenesis of dermonecrotic arachnidism.

Bites from the brown recluse spider and other Loxosceles arachnids result in dermonecrotic skin lesions. Neutrophils (PMN) are essential to the development of Loxosceles-induced skin lesions, but paradoxically, in vitro PMN activation is inhibited by direct exposure to Loxosceles venom. Neutrophil activation occurs in response to a myriad of soluble mediators that include members of both the alpha and beta chemokine families. Because arachnid envenomation results in the exposure of several different cell types to venom, we investigated venom-induced expression of alpha and beta chemokines in both endothelial cells (human umbilical vein; HUVEC) and epithelial cells (A549 pneumocytes). Chemokine-specific capture enzyme immunoassays (EIA) were used to measure Loxosceles deserta venom-induced alpha chemokines: interleukin-8 (IL-8), growth-related oncogene-alpha (GRO-alpha), and beta chemokines: monocyte chemoattractant protein-1(MCP-1), and regulated on activation, normal T cell expressed and secreted (RANTES) in cell-free conditioned media from HUVEC and A549 cell monolayers. Exposure of HUVECs (8 h) to Laxosceles venom resulted in the production of IL-8 (5.2+/-1.30 ng/ml), MCP-1 (1.44+/-0.11 ng/ml) and GRO-alpha (1.97+/-0.15 ng/ml) in a dose and time-dependent manner. Exposure of A549 cell monolayers to venom resulted in IL-8 (7.74+/-0.30 ng/ml), and MCP-1 (2.61+/-0.31 ng/ml), but neither GRO-alpha nor RANTES accumulated during an 8-hour incubation period. Chemokines accumulated in a venom dose and time-dependent manner. Neither cell type secreted RANTES in response to Loxosceles venom. These data indicate that Loxosceles spider venom is a potent inducer of alpha and beta chemokines in both endothelial and epithelial cell types. Based on the established roles of IL-8, MCP-1, and GRO-alpha, in inflammation, these observations have relevance to the pathophysiology of Loxosceles-induced dermonecrosis.

Cells, Cultured↗