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Biomedical subjects

K Wells

Publications and source records attributed to K Wells.

At least 37 records · Page 2Linked to original sources
PubMed2001

Treatment of lead poisoning with an immobilized chelator comparison with conventional therapy.

Lead poisoning is a global public health problem. In pregnant women it may result in developmental delays of the fetus, in children it my produce learning disability. Available chelators are nephrotoxic when eliminated as lead-chelator complexes. For safe removal of lead from the body we developed a "Lead-Hemopurifier" (L-HP), a device with an immobilized chelator. In vitro, applied to lead solutions, this device reduced the lead concentration. Applied to dogs with lead intoxication, Lead-HP-s removed lead from the blood; this was continuously replaced by lead from the bones until the skeleton was cleared from lead deposit. Treatment of lead poisoning in dogs with Lead-HP-s compared favorably with Versenate treatment of children with lead toxicity. This report demonstrates the in vivo efficiency and safety of this new detoxfication method. Methods to induce lead poisoning in dogs and procedures to identify lead released from skeletal deposits are described.

Animals↗
PubMed2000

A phase I trial of andrographolide in HIV positive patients and normal volunteers.

A phase I dose-escalating clinical trial of andrographolide from Andrographis paniculata was conducted in 13 HIV positive patients and five HIV uninfected, healthy volunteers. The objectives were primarily to assess safety and tolerability and secondarily to assess effects on plasma virion HIV-1 RNA levels and CD4(+) lymphocyte levels. No subjects used antiretroviral medications during the trial. Those with liver or renal abnormalities were excluded. The planned regimen was 5 mg/kg bodyweight for 3 weeks, escalating to 10 mg/kg bodyweight for 3 weeks, and to 20 mg/kg bodyweight for a final 3 weeks. The trial was interrupted at 6 weeks due to adverse events including an anaphylactic reaction in one patient. All adverse events had resolved by the end of observation. A significant rise in the mean CD4(+) lymphocyte level of HIV subjects occurred after administration of 10 mg/kg andrographolide (from a baseline of 405 cells/mm(3) to 501 cells/mm(3); p = 0.002). There were no statistically significant changes in mean plasma HIV-1 RNA levels throughout the trial. Andrographolide may inhibit HIV-induced cell cycle dysregulation, leading to a rise in CD4(+) lymphocyte levels in HIV-1 infected individuals.

Administration, Oral↗
PubMed2000

The performance of a CCD digital autoradiography imaging system.

Autoradiography is a widely used technique for imaging trace quantities of radioactivity within biological samples, conventionally using photographic film. This method produces images with high spatial resolution, but it suffers from very low sensitivity and poor dynamic range. Digital autoradiography systems with greatly improved sensitivity and linearity are commercially available, but the spatial resolution is usually much less than that achieved using film. We report here the design, construction and characterization of a novel digital autoradiography system based on scientific-grade charged coupled devices (CCDs). Images of x-ray and beta emissions from radionuclides commonly used in autoradiography show that the system can perform high-speed quantitative imaging with a spatial resolution of approximately 30, microm. Using a frame by frame acquisition method the dynamic range is shown to be at least three orders of magnitude. The absolute detection efficiency is comparable to the best of the currently available digital systems. CCD images of 125I and 14C radioisotope distributions in tissue samples are superior to the equivalent film images and have been acquired in 1-10% of the time.

Animals↗
PubMed2000

Recognition of N-glycolylneuraminic acid linked to galactose by the alpha2,3 linkage is associated with intestinal replication of influenza A virus in ducks.

The hemagglutinin (HA) of H3 human influenza viruses does not support viral replication in duck intestine despite its avian origin. A Leu-to-Gln mutation at position 226 and a Ser-to-Gly mutation at position 228 in the HA of human A/Udorn/307/72 (H3N2) permit a reassortant virus [human Udorn HA, with all other genes from A/mallard/New York/6750/78 (H2N2)] to replicate in ducks. To understand the molecular basis of this change in host range restriction, we investigated the receptor specificity of duck influenza viruses as well as of human-duck virus reassortants. The results indicate that the recognition of a glycoconjugate moiety possessing N-glycolneuramic acid (NeuGc) linked to galactose by the alpha2,3 linkage (NeuGcalpha2,3Gal) is associated with viral replication in duck intestine. Immunofluorescence assays with NeuGcalpha2,3Gal-specific antiserum detected this moiety primarily on the crypt epithelial cells of duck colon. Such recognition, together with biochemical evidence of NeuGc in crypt cells, correlated exactly with the ability of the virus to replicate in duck colon. These results suggest that recognition of the NeuGcalpha2,3-Gal moiety plays an important role in the enterotropism of avian influenza viruses.

Animals↗
PubMed2000

Health insurance may be improving--but not for individuals with mental illness.

OBJECTIVE: To explore the question of how insurance coverage has changed among individuals with mental problems compared to the general population in the last two years. DATA SOURCES: HealthCare for Communities, a national survey to track health system changes. PRINCIPAL FINDINGS: The percentage of uninsured persons in the general population has not changed very much, and more respondents believe that health insurance coverage has improved rather than deteriorated over the years 1996 to 1998. However, among individuals with probable mental health disorders, more have lost insurance in those two years than have gained it and more report decreases in health benefits. Individuals with worse mental health consistently report a deterioration of access to care compared to individuals with better mental health. CONCLUSIONS: Substantial activity has taken place in state and federal legislation to increase the mental health benefits offered by health insurance. Although this activity could have improved health insurance especially for individuals with mental illness, such persons continue to fare significantly worse than the general population.

Adult↗
PubMed1999

Lymphatic mapping for melanomas of the upper extremity.

Over a period of 4 years, 127 consecutive patients with upper extremity melanomas were identified from a prospectively accrued database. A protocol consisting of preoperative lymphoscintigraphy and intraoperative lymphatic mapping and with a vital blue dye and radiocolloid was used; the protocol had a 98% success rate of identifying the sentinel lymph node (SLN). Preoperative lymphoscintigraphy identified unpredictable cutaneous lymphatic flow in 15 (12%) of the patients. These discordant areas would not have been included in classic regional node dissection and possible sites of metastatic disease would not have been identified. Metastatic disease was identified within the SLNs in 12 (9%) of the patients. Of the 12 patients with a positive SLN, 2 (17%) were found on complete node dissection to have metastatic disease in higher nodes in the regional basin. The SLN was the only site of disease in 10 of these 12 patients with documented metastases in the regional basin. Patients with a negative SLN biopsy can be spared the morbidity and expense of a complete lymph node dissection.

Arm↗
PubMed1999

Green fluorescent protein as a reporter to monitor gene expression and food colonization by Aspergillus flavus.

Transformants of Aspergillus flavus containing the Aequorea victoria gfp gene fused to a viral promoter or the promoter region and 483 bp of the coding region of A. flavus aflR expressed green fluorescence detectable without a microscope or filters. Expression of green fluorescent protein fluorescence was correlated with resistance to aflatoxin accumulation in five corn genotypes inoculated with these transformants.

Aspergillus flavus↗
PubMed1999

Biological heterogeneity, including systemic replication in mice, of H5N1 influenza A virus isolates from humans in Hong Kong.

An H5N1 avian influenza A virus was transmitted to humans in Hong Kong in 1997. Although the virus causes systemic infection and is highly lethal in chickens because of the susceptibility of the hemagglutinin to furin and PC6 proteases, it is not known whether it also causes systemic infection in humans. The clinical outcomes of infection in Hong Kong residents ranged widely, from mild respiratory disease to multiple organ failure leading to death. Therefore, to understand the pathogenesis of influenza due to these H5N1 isolates, we investigated their virulence in mice. The results identified two distinct groups of viruses: group 1, for which the dose lethal for 50% of mice (MLD50) was between 0.3 and 11 PFU, and group 2, for which the MLD50 was more than 10(3) PFU. One day after intranasal inoculation of mice with 100 PFU of group 1 viruses, the virus titer in lungs was 10(7) PFU/g or 3 log units higher than that for group 2 viruses. Both types of viruses had replicated to high titers (>10(6) PFU/g) in the lungs by day 3 and maintained these titers through day 6. More importantly, only the group 1 viruses caused systemic infection, replicating in nonrespiratory organs, including the brain. Immunohistochemical analysis demonstrated the replication of a group 1 virus in brain neurons and glial cells and in cardiac myofibers. Phylogenetic analysis of all viral genes showed that both groups of Hong Kong H5N1 viruses had formed a lineage distinct from those of other viruses and that genetic reassortment between H5N1 and H1 or H3 human viruses had not occurred. Since mice and humans harbor both the furin and the PC6 proteases, we suggest that the virulence mechanism responsible for the lethality of influenza viruses in birds also operates in mammalian hosts. The failure of some H5N1 viruses to produce systemic infection in our model indicates that multiple, still-to-be-identified, factors contribute to the severity of H5N1 infection in mammals. In addition, the ability of these viruses to produce systemic infection in mice and the clear differences in pathogenicity among the isolates studied here indicate that this system provides a useful model for studying the pathogenesis of avian influenza virus infection in mammals.

Animals↗
PubMed1998

Efficacy of hyperthermic isolated limb perfusion for extremity-confined recurrent melanoma.

BACKGROUND: Recurrent melanoma of the extremity has been treated by local excision, systemic chemotherapy, amputation, or a combination of these approaches. Hyperthermic isolated limb perfusion (HILP) provides a method of limb preservation through isolation, allowing the administration of chemotherapy in higher doses than is possible through systemic treatment. METHODS: An experimental group of 59 HILP patients with melanoma recurrences of the extremity was studied prospectively. A control group of 248 melanoma patients with similar recurrences was excluded from HILP because their recurrences were in non-extremity locations. The experimental group underwent HILP and excision; the control group had excision only. The experimental procedure consisted of vascular isolation of the affected extremity and a 1-hour perfusion with melphalan. Temperatures were maintained at 40 degrees C in the perfusion circuit. RESULTS: The HILP patients had a lower rate of locoregional recurrence (P=.028) and demonstrated increased survival (P=.026) compared to the control group. In multivariate regression analysis, which included age, ulceration and thickness of the primary, and the treatment variable of perfusion, age (P=.02) and perfusion for the treatment of recurrence (P=.006) were significant predictors of survival. CONCLUSIONS: HILP improves prognosis by sterilizing the treated extremity, controlling locoregional disease, and perhaps preventing metastasis, thus having a positive impact on overall survival.

Antineoplastic Agents↗
PubMed1998

Influence of host species on the evolution of the nonstructural (NS) gene of influenza A viruses.

The matrix (M) and nonstructural (NS) genes of influenza A viruses each encode two overlapping proteins. In the M gene, evolution of one protein affects that of the other. To determine whether or not this evolutionary influence operating between the two M proteins also occurs in the NS gene, we sequenced the NS genes of 36 influenza A viruses isolated from a broad spectrum of animal species (wild and domestic birds, horses, pigs, humans, and sea mammals) and analyzed them phylogenetically, together with other previously published sequences. These analyses enabled us to conclude the following host species-related points that are not found in the other influenza A virus genes and their gene products. (1) The evolution of the two overlapping proteins encoded by the NS gene are lineage-dependent, unlike the M gene where evolutionary constraints on the Ml protein affect the evolution of the M2 protein (Ito et al.. J. Virol. 65 (1991) 5491 5498). (2) The gull-specific lineage contained nonH13 gull viruses and the non-gull avian lineage contained H13 gull viruses, indicating that the gull-specific lineage does not link to the H13 HA subtype in the NS gene unlike findings with other genes. (3) The branching topology of the recent equine lineage (H7N7 viruses isolated after 1973 and H3N8) indicates recent introduction of the NS, M, and PB2 genes into horses from avian sources by genetic reassortment.

Animals↗
PubMed1998

A randomized, prospective, double-blind comparison of midazolam (Versed) and emulsified diazepam (Dizac) for opioid-based, conscious sedation in endoscopic procedures.

OBJECTIVE: We completed a prospective, randomized, double-blinded clinical trial to compare the quality of sedation with two benzodiazepines (emulsified diazepam and midazolam) for endoscopic procedures. METHODS: Adult patients undergoing esophagogastroduodenoscopy or colonoscopy were eligible. Exclusion criteria included: drug allergies, altered mental status, untreated glaucoma, active pancreatitis, hyperlipidemia, resident physician training, or cases done outside the Endoscopy unit. Nurses began the sedation process by administering an opioid followed immediately by administering study drugs until patients were adequately sedated. At completion of the procedure, both the physician and the nurse rated whether the patient's sedation appeared to be adequate. In addition, before discharge, patients were asked to rate the quality of sedation. RESULTS: A total of 111 patients were randomized to the emulsified diazepam group and 100 to the midazolam group. There was no difference in the physician's assessment of quality of sedation between the groups (p > 0.05). The length of time to sedation, total procedure time, and recovery time were similar between both groups. The estimated cost of using emulsified diazepam was approximately 50% less than that of midazolam, with an equal quality of sedation. CONCLUSION: Neither the physicians, nurses, nor the patients could detect a difference between sedation produced by the drugs. We conclude that both drugs were equally effective for sedation for both upper and lower endoscopic procedures. Based on the results of this trial, we suggest that increased use of emulsified diazepam would markedly reduce the cost without altering the quality of sedation. The cost savings would be at least $50,000/yr at our institution.

Adult↗
PubMed1998

The role of influenza A virus hemagglutinin residues 226 and 228 in receptor specificity and host range restriction.

Influenza A viruses can be isolated from a variety of animals, but their range of hosts is restricted. For example, human influenza viruses do not replicate in duck intestine, the major replication site of avian viruses in ducks. Although amino acids at positions 226 and 228 of hemagglutinin (HA) of the H3 subtype are known to be important for this host range restriction, the contributions of specific amino acids at these positions to restriction were not known. Here, we address this issue by generating HAs with site-specific mutations of a human virus that contain different amino acid residues at these positions. We also let ducks select replication-competent viruses from a replication-incompetent virus containing a human virus HA by inoculating animals with 10(10.5) 50% egg infectious dose of the latter virus and identified a mutation in the HA. Our results showed that the Ser-to-Gly mutation at position 228, in addition to the Leu-to-Gln mutation at position 226 of the HA of the H3 subtype, is critical for human virus HA to support virus replication in duck intestine.

Animals↗
PubMed1997

The cysteine residues of the M2 protein are not required for influenza A virus replication.

The M2 protein of influenza A virus functions as an ion channel. It contains three cysteine residues: cysteines 17 and 19, which form disulfide bonds in the ectodomain, and cysteine 50 which is acylated. To understand the role of these cysteine residues in virus replication, we used reverse genetics to create influenza viruses in which the individual cysteines were mutated and a virus in which all three cysteines were changed to serine. The M2 cysteine mutants that lacked either of the cysteine residues in the ectodomain and the mutant that lacked all three residues had appreciably lower amounts of M2 oligomers than did the wild-type virus when examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. None of the mutants, however, were defective in replication, either in vitro or in ferrets and mice. These findings demonstrate that noncovalent interactions are sufficient for the M2 protein to form functional oligomers for virus replication and that its cysteine residues are dispensable for influenza virus replication in vitro and in vivo.

Amino Acid Substitution↗
PubMed1997

Multiple primary melanomas: implications for screening and follow-up programs for melanoma.

BACKGROUND: Once individuals are diagnosed with malignant melanoma, they are at an increased risk of developing another melanoma when compared with the normal population. METHODS: To determine the impact of an intensive follow-up protocol on the stage of disease at diagnosis of subsequent primary melanomas, a retrospective query was performed of an electronic medical record database of 2,600 consecutively registered melanoma patients. RESULTS: Sixty-seven patients (2.6%) had another melanoma diagnosed at the time of presentation to the clinic or within 2 months (synchronous) and another 44 patients (1.7%) developed a second primary melanoma during the follow-up period (metachronous). For the 44 patients diagnosed with metachronous lesions, the Breslow mean tumor thickness for the first invasive melanoma was 2.27 mm compared with 0.90 mm for the second melanoma. The first melanomas diagnosed are thicker by an average of 3.8 mm (p = 0.008). The mean Clark level for the initial melanoma was greater than the mean level for subsequently diagnosed melanomas (p = 0.002). Twenty-three percent of the initial melanomas were ulcerated, whereas only one of the second primary lesions showed this adverse prognostic factor (p = 0.002). CONCLUSIONS: Once individuals are diagnosed with melanoma, they are in a high-risk population for having other primary site melanomas diagnosed and should be placed in an intensive follow-up protocol consisting of a complete skin examination.

Adult↗
PubMed1997

Neuraminidase hemadsorption activity, conserved in avian influenza A viruses, does not influence viral replication in ducks.

The N1 and N9 neuraminidase (NA) subtypes of influenza A viruses exhibit significant hemadsorption activity that localizes to a site distinct from that of the enzymatic active site. To determine the conservation of hemadsorption activity among different NAs, we have examined most of the NA subtypes from avian, swine, equine, and human virus isolates. All subtypes of avian virus NAs examined and one equine virus N8 NA possessed high levels of hemadsorption activity. A swine virus N1 NA exhibited only weak hemadsorption activity, while in human virus N1 and N2 NAs, the activity was detected at a much lower level than in avian virus NAs. NAs which possessed hemadsorption activity for chicken erythrocytes (RBCs) were similarly able to adsorb human RBCs. However, none of the hemadsorption-positive NAs could bind equine, swine, or bovine RBCs, suggesting that RBCs from these species lack molecules, recognized by the NA hemadsorption site, present on human and chicken RBCs. Mutagenesis of the putative hemadsorption site of A/duck/Hong Kong/7/75 N2 NA abolished the high level of hemadsorption activity exhibited by the wild-type protein but also resulted in a 50% reduction of the NA enzymatic activity. A transfectant virus, generated by reverse genetics, containing this mutated NA replicated 10-fold less efficiently in chicken embryo fibroblast cultures than did a transfectant virus expressing the wild-type NA. However, both viruses replicated equally well in Peking ducks. Although conservation of NA hemadsorption activity among avian virus NAs suggests the maintenance of a required function of NA, loss of the activity does not preclude the replication of the virus in an avian host.

Animals↗
PubMed1997

The Role of Selective Lymphadenectomy in Breast Cancer.

BACKGROUND: Axillary node dissection is considered a standard staging procedure in patients with breast cancer. The procedure is associated with significant morbidity and provides pathologists with many lymph nodes to evaluate. METHODS: A total of 174 women participated in a trial that included preoperative lymphoscintigraphy and intraoperative lymphatic mapping using a combination of a vital blue dye and radiocolloid mapping. RESULTS: The intraoperative lymphatic mapping correctly identified a sentinel lymph node (SLN) in 160 (92%) of 174 patients. One skip metastasis (0.7%) occurred in 136 women who had a subsequent complete node dissection. CONCLUSIONS: Lymphatic mapping and SLN biopsy using a combination of mapping techniques provide accurate nodal staging for women with breast cancer. With this technique, approximately 70% to 80% of women with no axillary metastases could be spared the morbidity of a complete node dissection.

Journal Article↗