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Biomedical subjects

R Lee

Publications and source records attributed to R Lee.

At least 181 records · Page 10Linked to original sources
PubMed1996

Interferon treatment for chronic hepatitis C infection in hemophiliacs--influence of virus load, genotype, and liver pathology on response.

In this study, we assessed the effectiveness of interferon treatment in 31 hemophiliacs with chronic hepatitis C virus (HCV) infection. Interferon alfa-2a (3 MU three times weekly) was administered for 6 months. Response was assessed by both serial alanine transaminase (ALT) and HCV RNA levels measured by a sensitive semiquantitative polymerase chain reaction (PCR) method. HCV genotype was determined by restriction fragment length polymorphism (RFLP), and evidence of changing genotypes during interferon therapy was sought. Severity of liver disease was assessed by both noninvasive and invasive methods, including laparoscopic liver inspection and biopsy. Sustained normalization of ALT levels occurred in eight patients (28%), and seven (24%) became nonviremic as assessed by PCR (<80 HCV/mL). Responders universally cleared HCV RNA within 2 months of starting interferon. Genotype 3a was associated with a favorable response to interferon. No evidence was found for a change in circulating genotype in patients who failed to respond to interferon or who relapsed. This study confirms that response rates to interferon are low in hemophiliacs as compared with other groups with chronic HCV infection. We have also demonstrated that virus load measurement over the first 8 to 12 weeks of treatment is an extremely useful method to identify responders at an early stage.

Adolescent↗
PubMed1996

Hematopoietic potential of cryopreserved and ex vivo manipulated umbilical cord blood progenitor cells evaluated in vitro and in vivo.

The hematopoietic potential of cryopreserved and ex vivo manipulated umbilical cord blood (UCB) samples was evaluated in vitro and in vivo. Phenotypic analysis shows that approximately 1% of cord blood mononuclear cells express high levels of CD34 antigen on their surface (CD34hi), but none of a panel of lineage antigens (Lin-), suggesting that they are hematopoietic progenitor cells that have not yet committed to a specific lineage. Approximately 1% of CD34hi/Lin- cells are primitive hematopoietic progenitors that produce B lymphoid and multiple myeloid progeny for up to 7 weeks in stromal cell cultures. Twenty-one percent (+/- 13%) of CD34hi/Lin- cells also express low levels of the Thy-1 antigen and are threefold to fourfold enriched over CD34hi/Lin- cells in primitive hematopoietic potential as measured by long-term culture and phenotypic analysis. One-week liquid cultures of CD34-enriched UCB progenitor cells in the presence of interleukin (IL)-3, IL-6, and stem cell factor (SCF) results in a two-fold to threefold expansion of progenitors capable of reinitiating long-term stromal cell cultures. Only the CD34hi/Thy-1+/Lin- cell population was capable of maintaining progenitors with secondary transfer potential in long-term stromal cell cultures and is thus postulated to contain all of the primitive hematopoietic stem cells in UCB. The in vivo transplantation potential of UCB was also measured. Ex vivo manipulated UCB progenitor cells were used to engraft irradiated human thymus fragments implanted in severe combined immunodeficiency (SCID) mice. Thymic engraftment with >5% donor-derived cells and a normal CD4/CD8 distribution was observed in 19 of 23 tissues tested. UCB cells from in vitro expansion cultures engrafted with efficiencies comparable to nonexpanded cells. Similar results were obtained for UCB engraftment of human bone fragments implanted in SCID mice. In all cases, engraftment was achieved in competition with endogenous competitor stem cells and across major histocompatibility barriers. Taken together, this data demonstrates that human UCB is a rich source of multipotent hematopoietic progenitors that can be cryopreserved, enriched by physical methods, and expanded in a limited fashion without measurable loss of long-term culture or in vivo engrafting potential as measured in these assays.

Animals↗
PubMed1996

Comparison of transrectal ultrasound prostatic volume estimation with magnetic resonance imaging volume estimation and surgical specimen weight in patients with benign prostatic hyperplasia.

There are relatively few reports in the literature comparing transrectal ultrasound (TRUS) to magnetic resonance imaging (MRI) in estimating the volume of the prostate in the management of benign prostatic hyperplasia (BPH). In this study, we compared volumes determined by TRUS with MRI and TRUS-estimated weights with surgical specimen weights. The main findings of this study were (a) TRUS and MRI measurement of prostate volumes are quite similar; and (b) TRUS underestimates (by 10%) the prostatic weight as determined from the surgical specimens. A better volume estimate can thus be obtained by multiplying the TRUS measurement by a factor of 1.10. We conclude that because TRUS is cheap, user-friendly, noninvasive, and equally as accurate as MRI, it should be the preferred modality in the follow-up of BPH patients.

Humans↗
PubMed1996

Infection surveillance and antibiotic utilization in a community-based skilled nursing facility.

To survey the types of suspect infections, the antibiotic utilization and the patterns of antibiotic resistance among bacterial pathogens in a community Skilled Nursing Facility (SNF), we conducted a 20-month prospective observational surveillance program comprising all 585 patients admitted to a 149-bed private community SNF. Data were collected form medical charts, laboratory reports and nurses reports. Overall, 41% of the patients developed at least one presumptive nosocomial infection, and 54% of the patients received one or more antibiotic treatments. The overall presumptive nosocomial infection rate was 7.2 per 1000 patient days. The most common sites of presumptive nosocomial infection were the urinary tract (38%) and the respiratory tract (28%). The most common pathogens overall were E. coli (25%). Antibiotic groups used most frequently were the quinolones (22% of prescriptions). Thirty-nine percent of the Staphylococcus aureus isolates associated with suspected infections were resistant to methicillin, and of these 94% were also resistant to ciprofloxacin. Most of the resistant S. aureus isolates were from indwelling catheter-associated with UTIs. Infections associated with quinolone resistant strains of gram-negative bacilli were infrequent. No epidemiologic evidence of nosocomial clustering was apparent.

Adolescent↗
PubMed1996

Dopexamine prevents depression of mesenteric blood flow caused by positive end-expiratory pressure in rats.

BACKGROUND: The purpose of this study was to investigate the effects of two vasoactive agents, dopamine and dopexamine, on the depression of mesenteric blood flow caused by positive end-expiratory pressure (PEEP) during mechanical ventilation. METHODS: Sprague-Dawley rats were mechanically ventilated with either no PEEP (control group) or increasing levels of PEEP (PEEP group) up to 20 cm H2O pressure. We evaluated PEEP's effect on blood pressure, cardiac output (CO), and the mesenteric microcirculation with a continuous infusion of 2.5 or 12.5 micrograms/kg/min dopamine or 1, 3, or 5 micrograms/kg/min dopexamine. RESULTS: PEEP caused a 20% to 25% decrease in mean arterial pressure and a 30% decrease in CO at both 15 and 20 cm H2O of PEEP (all p < 0.05 versus baseline). Low dose dopamine partially corrected the decrease in CO to 16% and 21% below baseline at 15 and 20 cm H2O of PEEP, respectively (both p < 0.05 versus PEEP group) and partially ameliorated the depression of mesenteric blood flow associated with the application of PEEP. High dose dopamine did not positively affect either CO or mesenteric blood flow. Dopexamine had little effect on CO compared with dopamine. All three doses of dopexamine blocked the effect of PEEP on mesenteric blood flow (p < 0.05 compared with the PEEP group at all levels of PEEP, p < 0.05 compared with the low dose dopamine group at 15 and 20 cm H2O of PEEP). CONCLUSIONS: Dopexamine is superior to dopamine in protecting mesenteric blood flow in the face of increasing levels of PEEP.

Animals↗
PubMed1996

Restricted B-cell responses to microbial challenge of the respiratory tract.

The local B-cell response in the respiratory tract to infectious challenge has been analyzed in pigs and calves using two techniques: flow cytometry and antibody secreting cell (ASC) probes. Pneumonia in pigs caused by experimental infection with Mycoplasma hyopneumoniae resulted in a 25-fold increase in the B-cell population in BAL and lung parenchyma 28 days post infection. ASC probes revealed that the B-cell response of immune pigs to a large challenge infection was localized to lung parenchyma and tracheobronchal lymph nodes. Naive calves infected with Pasteurella multocida had a 5-fold increase in the B-cell blast population in lung parenchyma and BAL, and a greater than 60-fold increase in the draining lymph node at 9 days post infection. The ASC probes prepared post challenge from immune calves showed the response to be localized to the draining lymph nodes, with little response in lung parenchyma. A major finding was that ASC probes prepared from lung parenchyma and from pulmonary lymph nodes of both calves and pigs recognized a restricted range of bacterial antigens, particularly compared to the range of antigens recognized by concurrently circulating sera. The use of ASC probes demonstrates that there is a restricted B-cell repertoire in the respiratory tract.

Animals↗
PubMed1996

Investigation of chronic hepatitis C infection in individuals with haemophilia: assessment of invasive and non-invasive methods.

Hepatitis C virus (HCV) infection is the major cause of chronic liver disease in individuals with haemophilia. A wide spectrum of disease severity is found in this group, ranging from mild hepatitis to cirrhosis. We have studied a cohort of 87 anti-HCV positive haemophiliacs who have been infected with HCV for 10-25 years and assessed the relative value of invasive and non-invasive methods of evaluating liver disease. The severity of liver disease was assessed using ultrasound scan (n = 77), upper GI endoscopy (n = 50), laparoscopic liver inspection (n = 33) and liver biopsy (n = 22). Invasive investigations were performed without any significant bleeding complications. Evidence of severe liver disease was found in approximately 25% of patients. There was agreement between the severity of liver histology and the information derived from the laparoscopic liver inspection, endoscopy and ultrasound in 86%. Co-infection with HIV was significantly associated with more severe liver disease (P = 0.006). This study provides further evidence that liver disease is emerging as a major complication in haemophiliacs and severe liver disease is more common in those co-infected with HIV. We have shown the potential value of laparoscopic liver inspection, in combination with endoscopy and ultrasound, in staging the extent of liver disease, and suggest that most patients may be managed without resorting to liver biopsy.

Adolescent↗
PubMed1996

Colonization by Staphylococcus aureus resistant to methicillin and ciprofloxacin during 20 months' surveillance in a private skilled nursing facility.

OBJECTIVE: To evaluate endemic colonization with Staphylococcus aureus resistant to methicillin, ciprofloxacin, or both among patients of a private skilled nursing facility, with regard to colonization rate and site, and relation to infection and prior antibiotic use. DESIGN: Prospective quarterly culture surveillance of nares and rectal specimens over 20 months' observation. RESULTS: The mean prevalence was 3.8% in new admissions and 5.4% for in-house patients; cumulatively, 7.5% of the patients were colonized during the study period. The colonization rate remained stable during the study period. Screening of rectal, as well as nares, specimens detected substantially more colonized patients than would have been detected by nasal cultures alone. Five to seven percent of the colonized patients developed later infection with methicillin-ciprofloxacin-resistant S aureus. Colonized patients did not differ significantly from the noncolonized group in prior use of quinolones, but the colonized group was exposed significantly more frequently to other antibiotics than the noncolonized group. Eighty-three percent of methicillin-resistant S aureus (MRSA) isolated from infections and 89% from colonization were also ciprofloxacin resistant. CONCLUSION: Although all infecting and most colonizing isolates of MRSA were resistant to quinolones, the overall rate of colonization remained low and stable despite the continued use of quinolones. The findings suggest that good infection control practice has prevented broader spread of such strains in this facility.

Adolescent↗
PubMed1996

Pediatric and neonatal critical care transport: a comparison of therapeutic interventions.

OBJECTIVE: To compare the therapeutic interventions provided to newborn and pediatric patients by a dedicated combined neonatal pediatric critical care transport team. METHOD: From November 1987 through December 1989 we prospectively compared the number of therapeutic interventions performed by the critical care transport team on newborns and pediatric patients. The transport team (critical care physician [PL3 or greater], pediatric respiratory therapist, critical care nurse), recorded all therapeutic interventions, including both procedural and pharmacologic, for 213 newborn and 149 pediatric consecutive transports. Data were analyzed by analysis of variance or chi 2 statistic. RESULTS: All patients were admitted to either the pediatric or the neonatal intensive care unit, and over 80% of both age groups received assisted ventilation. Newborns commonly suffered from respiratory diseases (159/213), while pediatric patients suffered from respiratory (52/149), central nervous system (28/149), and traumatic conditions (37/149). Airway maintenance procedural interventions (intubation, ventilation) were the commonest in both groups, although more frequent in neonates. Neonates received antibiotics and morphine (P < 0.05) while pediatric patients received anticonvulsants and respiratory drugs (P < 0.05) more frequently. Newborns received significantly more interventions than pediatric patients (average 3.56 vs 2.93, P < 0.05). Newborns also received significantly more procedural interventions (2.06 vs 1.36, P = < 0.05) including intubation (34.7% vs 15.4%, P < 0.05) and the initiation of mechanical ventilation (38% vs 22%, P < 0.05). CONCLUSION: Overall, newborns received more interventions, including intubation, and ventilation from the transport team than did pediatric patients. Our data suggest that combined pediatric neonatal transport teams should be prepared to intervene in a wide range of conditions from preterm respiratory distress to the multiply traumatized adolescent.

Child↗
PubMed1996

Influence of referring physicians on interventions by a pediatric and neonatal critical care transport team.

The objective of this study was to determine the influence of: a) pediatrician versus nonpediatrician referrals on a transport team's therapeutic interventions and b) referring physician's year of graduation on interventions performed by the transport team. From November 1987 through December 1989 we prospectively compared the therapeutic interventions performed by the critical care transport team on newborns and pediatric patients with the referring physician's specialty and year of graduation. The transport team (critical care physician [PL3 or greater], registered respiratory therapist, critical care nurse), recorded all therapeutic interventions, including both procedural and pharmacologic, for 213 newborn and 149 consecutive pediatric transports. Referring physicians were categorized as pediatricians and nonpediatricians. Data were analyzed by analysis of variance, chi2, or linear regression. All patients were admitted to either the pediatric or the neonatal intensive care unit, and over 80% of both age groups received assisted ventilation. Newborns referred by nonpediatricians required significantly more procedural interventions (2.64 vs 1.91, P = 0.016) than those referred by pediatricians. The opposite relationship was observed among pediatric patients in that children referred by pediatricians received more frequent intervention (P = 0.008) than those referred by nonpediatricians. There was a significant inverse relationship between the referring physicians year of medical school graduation and the number of therapeutic interventions (total interventions = 6.17 - 0.040 x graduation year, P = 0.01) and procedural interventions (procedural interventions = 3.54 - 0.024 x graduation year, P = 0.01). We found that the referring physicians' medical training affected the number of interventions their patients received. Similarly, patients were likely to receive more interventions if the referral physicians training was not recent. These data have educational implications and support the concepts of continuing medical education, recertification, and maintenance of skills among physicians providing care to critically ill newborns and pediatric patients.

Critical Care↗
PubMed1996

Genomic structure of the human OB receptor and identification of two novel intronic microsatellites.

Identification of the OB (leptin) receptor (OBR) as the gene that is defective in diabetes (Leprdb) mice and fatty (Leprfa) rats provides an important candidate gene for the study of the genetics of human obesity. We defined the boundaries of the 18 coding exons for the long form of OBR, and sequenced the immediately adjacent intronic regions. These sequences can be used to generate reagents for genetic analysis (e.g., direct sequencing, single-stranded conformational polymorphism analysis, etc.) of the possible role of OBR in the regulation of adiposity in humans. In addition, we have identified two highly polymorphic intronic microsatellites that can be scored with the polymerase chain reaction.

Animals↗
PubMed1996

A review of the radiological features of intracranial meningiomas.

To evaluate the role of radiological imaging of meningiomas in confirming the diagnosis and as a neuroanatomical aid to surgical planning, 115 patients with surgically excised meningiomas between 1990 and 1993 were studied. Computed tomography (CT), magnetic resonance imaging (MRI) (on a 0.5 T unit) and angiography were reviewed, and compared with histopathology (when available). Seventy-eight CT, 89 MRI and 85 angiographic studies were reviewed, and correlated with histopathology in 67 cases. In 48 cases, the surgical specimens could not be pathologically classified. The most common lesion sites were the cerebral convexities, falx and sphenoidal ridges. True demarcation of cleavage planes was seen on 73% of MRI and 10% of CT studies. Computed tomography showed hyperostosis in 27% and MRI in 7% of studies. Tumours enhanced strongly with contrast in 98% of CT scans. On MRI there were variable signal intensities on different sequences, and no correlation between signal intensities and histological subtype was found. Oedema was present in 59% of CT and 66% of MRI studies, and was most pronounced in lesions > 3 cm in diameter. Tumour calcification was seen in 62% of CT and 8% of MRI studies. Vascular abnormalities were seen on 65% of MRI, 21% of CT and 84% of angiogram studies. Angiographic tumour vascularity did not correlate with histologic subtype. All three imaging modalities have management roles: CT for bony changes and calcification, MRI for multiplanar and vessel anatomy imaging, and angiography for vessel delineation and embolization if required.

Aged↗
PubMed1996

Molecular characterization of an Aspergillus parasiticus dehydrogenase gene, norA, located on the aflatoxin biosynthesis gene cluster.

An Aspergillus parasiticus cDNA library was screened with monoclonal antibody raised against a purified A. parasiticus 43-kDa protein demonstrating norsolorinic acid reductase (NOR) activity. One immunopositive clone contained a cDNA insert of 1,418 bp. DNA sequence analysis of this cDNA identified an open reading frame of 1,167 bp that represented the norA gene. The deduced amino acid sequence of the norA coding region consisted of 388 residues capable of encoding a polypeptide of 43.7 kDa. Southern blot analysis of genomic DNA from A. parasiticus indicated that there may be an additional copy of norA. Western blot (immunoblot) analysis of crude protein extracts of A. parasiticus mycelia demonstrated a band of reactivity at 43 kDa only when the fungus was grown in a medium conducive to aflatoxin biosynthesis. Northern (RNA) blot analysis of total RNA from the fungus demonstrated a band of hybridization at about 1.5 kb. As observed with the fungal NORA protein, the norA transcript was present only when the fungus was grown in medium conducive to aflatoxin biosynthesis. Hybridization of the norA cDNA with cosmid DNAs known to encompass a major portion of the A. parasiticus and Aspergillus flavus aflatoxin biosynthetic pathway gene cluster placed the norA gene coding region just upstream of the ver-1 gene. The deduced amino acid sequence of norA had 49% amino acid identity with that of an aryl-alcohol dehydrogenase (aad) gene from Phanerochaete chrysosporium.

Aflatoxins↗
PubMed1996

The organization of ribosomal RNA processing correlates with the distribution of nucleolar snRNAs.

We have analyzed the organization of pre-rRNA processing by confocal microscopy in pea root cell nucleoli using a variety of probes for fluorescence in situ hybridization and immunofluorescence. Our results show that transcript processing within the nucleolus is spatially highly organized. Probes to the 5' external transcribed spacer (ETS) and first internal transcribed spacer (ITS1) showed that the excision of the ETS occurred in a sub-region of the dense fibrillar component (DFC), whereas the excision of ITS1 occurred in the surrounding region, broadly corresponding to the granular component. In situ labelling with probes to the snoRNAs U3 and U14, and immunofluorescence labelling with antibodies to fibrillarin and SSB1 showed a high degree of coincidence with the ETS pattern, confirming that ETS cleavage and 18 S rRNA production occur in the DFC. ETS, U14, fibrillarin and SSB1 showed a fine substructure within the DFC comprising closely packed small foci, whereas U3 appeared more diffuse throughout the DFC. A third snoRNA, 7-2/MRP, was localised to the region surrounding the ETS, in agreement with its suggested role in ITS1 cleavage. All three snoRNAs were also frequently observed in numerous small foci in the nucleolar vacuoles, but none was detectable in coiled bodies. Antibodies to fibrillarin and SSB1 labelled coiled bodies strongly, though neither protein was detected in the nucleolar vacuoles. During mitosis, all the components analyzed, including pre-rRNA, were dispersed through the cell at metaphase, then became concentrated around the periphery of all the chromosomes at anaphase, before being localized to the developing nucleoli at late telophase. Pre-rRNA (ETS and ITS1 probes), U3 and U14 were also concentrated into small bodies, presumed to be pre-nucleolar bodies at anaphase.

Base Sequence↗
PubMed1996

Fat body cells and calcium phosphate spherules induce ice nucleation in the freeze-tolerant larvae of the gall fly Eurosta solidaginis (Diptera, Tephritidae)

During the autumn, the third-instar larvae of the gall fly Eurosta solidaginis acquire freeze tolerance and their crystallization temperatures increase into the -8 to -10 &deg;C range. Despite conflicting reports, efficient endogenous ice nucleators have not been identified in this freeze-tolerant insect. We found large crystalloid spheres within the Malpighian tubules of overwintering larvae. Energy-dispersive X-ray microanalysis and infrared spectroscopy indicated that the spherules were a hydrate of tribasic calcium phosphate. To test for ice-nucleating activity, we placed the calcium phosphate spherules in 10 &micro;l of Schneider's insect medium and cooled them in a refrigerated bath. The addition of spherules increased the crystallization temperature of Schneider's medium by approximately 8 C, from -18.4&plusmn;0.8 &deg;C to -10.1&plusmn;0.9 &deg;C (mean &plusmn; s.e.m., N=20). Ice-nucleating activity (-10.9&plusmn;0.9 &deg;C) was also demonstrated in fat body cells suspended in 10 &micro;l of Schneider's medium. Both calcium phosphate spherules and fat body cells have ice-nucleating activity sufficiently high to explain whole-body crystallization temperatures. Furthermore, other crystalloid deposits, commonly found in diapausing or overwintering insects, also exhibited significant ice-nucleating activity. These endogenous crystalloid deposits represent a new class of heterogeneous ice nucleators that potentially regulate supercooling and promote freeze tolerance in E. solidaginis and possibly in other overwintering insects.

Journal Article↗
PubMed1996

Radiology in the neonatal intensive care unit: dose reduction and image quality.

This paper describes a prospective study of the diagnostic radiation doses received in a neonatal intensive care unit (NICU) for a representative radiological technique used at our institution for a number of years and a "low dose" technique similar to that recommended by the Commission of the European Communities (CEC). A 400 speed film-screen combination was used in both techniques. A total of 363 anteroposterior (AP) chest and abdominal films of 77 neonates were accrued. For each radiograph, the entrance skin dose (FSD), energy imparted (EI) and mean whole body dose were determined. For a neonatal AP chest, there was an 18% reduction in the mean ESD per radiograph from 20.0 muGy for the representative technique to 16.4 muGy for the low dose technique (p < 0.0005). The reduction in the mean EI per radiograph values for the two techniques from 7.9 muJ to 7.1 muJ (10%) was statistically significant at the p < 0.017 level, after compensating for the difference in mean field dimensions between the two patient cohorts. The mean whole body dose per radiograph reduction from 4.4 to 3.5 muGy (20%) was statistically significant at the p < 0.0028 level. It was determined that the ESD and EI could be fitted by an exponential function in the equivalent patient diameter, a single parameter indicative of neonate size. Absolute excess childhood cancer mortality risk per film was estimated using risk factors derived for fetal exposures. A "worst case" absolute excess mortality risk per chest radiograph was estimated to be 1.40 x 10(-7) for the conventional technique and was further reduced to 1.11 x 10(-7) for the low dose technique. A blind comparison of patient-matched film pairs for each technique was performed by three radiologists using criteria similar to those specified by the CEC. No statistically significant difference in clinical image quality was found between the two techniques.

Analysis of Variance↗
PubMed1996

Immunogenic and protective response in mice immunized with a purified, inactivated, Dengue-2 virus vaccine prototype made in fetal rhesus lung cells.

The feasibility of a purified, inactivated vaccine (PIV) against dengue type 2 (DEN-2) virus was explored. Dengue-2 virus strain 16681 was used for producing a monotypic PIV. Virus adapted to fetal rhesus lung (FRhL-2) cells was harvested from roller bottle culture supernatant fluids, concentrated, and purified on sucrose gradients. Analysis of purified virus preparations by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting showed primarily envelope (E) and premembrane (prM) antigens. These preparations had a purity, estimated from silver-stained gels, of approximately 70%, and a yield, based on recovery of virus and viral antigen, of 10-20%. The purified virus was inactivated with 0.05% formalin at 22 degrees C, or alternatively, with 7 mRads from a 60Co source. Vaccinated mice developed high titers of anti-DEN-2 virus neutralizing antibody and were partially protected from virus challenge. These results warrant further testing and development of PIVs for the other DEN virus serotypes.

Animals↗