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Biomedical subjects

J Keller

Publications and source records attributed to J Keller.

At least 91 records · Page 5Linked to original sources
PubMed2000

Women living with HIV: disclosure, violence, and social support.

This paper describes the frequency of women's disclosure of their HIV status, examines the extent to which they experience adverse social and physical consequences when others learn they are infected, and analyzes correlates of these negative outcomes. There were 257 HIV-positive women between the ages of 18 and 44, recruited from HIV/AIDS primary care clinics and from community sites, who completed a face-to-face interview. Women in the sample were 33 years old on average; 92% were African-American; 54% had less than 12 years of education; 56% had used intravenous drugs; and 30% knew they were HIV positive for 5 or more years. There were 97% who disclosed their HIV status; 64% told more than 5 people. Negative consequences associated with others knowing they were HIV-positive were reported by 44%, most commonly the loss of friends (24%), being insulted or sworn at (23%), and being rejected by family (21%). There were 10 women (4%) who reported being physically or sexually assaulted as a result of their being HIV positive, and 16% reported having no one they could count on for money or a place to stay. Violence was widespread in this sample, with 62% having experienced physical or sexual violence, including sexual abuse or rape (27%), being beaten up (34%), and weapon-related violence (26%). Logistic regression analysis indicated that women with a history of physical and sexual violence were significantly more likely to experience negative social and physical consequences when their infection became known to others, adjusting for age and the number of people women had disclosed to, both of which were only marginally significant. Partner notification policies and support programs must be responsive to the potential negative consequences associated with others learning that a woman is HIV positive. The high rates of historical violence in the lives of women living with HIV underscore the need for routine screening and intervention for domestic violence in all settings that provide health care to HIV-positive women.

Adolescent↗
PubMed2000

3,3',4,4'-Tetrachlorobiphenyl oxidation in fish, bird and reptile species: relationship to cytochrome P450 1A inactivation and reactive oxygen production.

Previously we showed that the polychlorinated biphenyl 3,3',4,4'-tetrachlorobiphenyl (TCB) caused a release of reactive oxygen species (ROS) from cytochrome P450 1A (CYP1A) of the fish scup (Stenotomus chrysops), and from rat and human CYP1A1. This was linked to a TCB- and NADPH-dependent oxidative inactivation of the enzyme, which in scup and rat was inversely related to the rates of TCB oxidation. We examined the relationship between rates of TCB oxidation, CYP1A inactivation and ROS production in liver microsomes from additional vertebrate species, including skate (Raja erinacea), eel (Anguilla rostrata), killifish (Fundulus heteroclitus), winter flounder (Pleuronectes americanus), chicken (Gallus domesticus), cormorant (Phalacrocorax auritus), gull (Larus argentatus), and turtle (Chrysemys picta picta). TCB oxidation rates were induced in all fish and birds treated with aryl hydrocarbon receptor agonists. Induced rates of TCB oxidation were <1 pmol/min/mg microsomal protein in all fish, and 6-14 pmol/min/mg in the birds. In all species but one, TCB oxidation rates correlated positively with EROD rates, indicating likely involvement of CYP1A in TCB oxidation. Incubation of liver microsomes of most species with TCB+NADPH resulted in an immediate (TCB-dependent) inhibition of EROD, and a progressive loss of EROD capacity, indicating an oxidative inactivation of CYP1A like that in scup. NADPH stimulated production of ROS (H(2)O(2) and/or O(2)(-*)) by liver microsomes, slightly in some species (eel) and greatly in others (chicken, turtle). Among the birds and the fish, NADPH-stimulated ROS production correlated positively with EROD activity. TCB caused a significant stimulation of ROS production by liver microsomes of flounder, killifish, cormorant and gull, as well as scup. The stimulation of CYP1A inactivation and ROS generation indicates an uncoupling of CYP1A by TCB in many species, and when compared between species, the rates of CYP1A inactivation correlated inversely with rates of TCB oxidation. Some feature(s) of binding/active site topology may hinder TCB oxidation, enhancing the likelihood for attack of an oxidizing species in the active site.

Acetone↗
PubMed2000

Right-posterior face processing anomaly in depression.

Evidence of a right-posterior brain anomaly was found in a study of 19 individuals with major depression and 15 controls. Participants performed a recognition-memory task involving positive, neutral, and negative face and word stimuli. Scalp brain wave topography suggested a region-specific anomaly in the depressed group. Individuals with major depression demonstrated a reduction in the N200 component of the event-related brain potential to faces and not words. Furthermore, results indicate that the regional anomaly is specific to positive facial stimuli. Findings are interpreted in light of a model of regional brain specialization in emotion and psychopathology.

Adult↗
PubMed2000

Mandibular bone density and fractal dimension in rabbits with induced osteoporosis.

OBJECTIVE: Our goal in this investigation was to examine the mandibular bone density and radiographic textural changes and the relationship between mandibular and spinal bone mineral density in an osteoporotic rabbit model. STUDY DESIGN: Three adult female New Zealand white rabbits in each of 4 groups received daily injections of cortisone acetate at a dosage of 0.0 (control), 3.0, 7.5, or 15.0 mg/kg for 4 weeks. The rabbits were then killed, and the mandible and spine of each animal were removed. Digital radiographs (70 kVp, 10 mA, 8 impulses) of the hemimandibles and spines were made. Lateral and anteroposterior bone densities of the lumbar spine (L2) were calculated, and average mandibular interdental bone density, fractal dimension, and gradient values were calculated. RESULTS: Correlation analysis revealed that cumulative steroid dose was strongly related to mandibular bone density (r = -0.80, P <.01), moderately related to mandibular fractal dimension (r = -0.61, P <. 05), and moderately related to anteroposterior lumbar spine density (r = -0.64, P <.05). Moderate correlations were found between mandibular interdental bone density and spinal density (r = 0.56, P <.05), but mandibular fractal dimension was not related to spinal density. CONCLUSIONS: In osteoporotic female rabbits, mandibular bone mineral density decreases in relation to spinal density and cumulative steroid dose. Mandibular fractal dimension decreases with cumulative steroid dose but is not significantly related to either mandibular density or spinal density.

Absorptiometry, Photon↗
PubMed2000

Identification of polyphosphate-accumulating organisms and design of 16S rRNA-directed probes for their detection and quantitation.

Laboratory-scale sequencing batch reactors (SBRs) as models for activated sludge processes were used to study enhanced biological phosphorus removal (EBPR) from wastewater. Enrichment for polyphosphate-accumulating organisms (PAOs) was achieved essentially by increasing the phosphorus concentration in the influent to the SBRs. Fluorescence in situ hybridization (FISH) using domain-, division-, and subdivision-level probes was used to assess the proportions of microorganisms in the sludges. The A sludge, a high-performance P-removing sludge containing 15.1% P in the biomass, was comprised of large clusters of polyphosphate-containing coccobacilli. By FISH, >80% of the A sludge bacteria were beta-2 Proteobacteria arranged in clusters of coccobacilli, strongly suggesting that this group contains a PAO responsible for EBPR. The second dominant group in the A sludge was the Actinobacteria. Clone libraries of PCR-amplified bacterial 16S rRNA genes from three high-performance P-removing sludges were prepared, and clones belonging to the beta-2 Proteobacteria were fully sequenced. A distinctive group of clones (sharing >/=98% sequence identity) related to Rhodocyclus spp. (94 to 97% identity) and Propionibacter pelophilus (95 to 96% identity) was identified as the most likely candidate PAOs. Three probes specific for the highly related candidate PAO group were designed from the sequence data. All three probes specifically bound to the morphologically distinctive clusters of PAOs in the A sludge, exactly coinciding with the beta-2 Proteobacteria probe. Sequential FISH and polyphosphate staining of EBPR sludges clearly demonstrated that PAO probe-binding cells contained polyphosphate. Subsequent PAO probe analyses of a number of sludges with various P removal capacities indicated a strong positive correlation between P removal from the wastewater as determined by sludge P content and number of PAO probe-binding cells. We conclude therefore that an important group of PAOs in EBPR sludges are bacteria closely related to Rhodocyclus and Propionibacter.

Actinobacteria↗
PubMed2000

Newly recognized herpesvirus causing malignant catarrhal fever in white-tailed deer (Odocoileus virginianus).

Malignant catarrhal fever (MCF) was diagnosed by clinical signs and lesions in five out of six white-tailed deer (Odocoileus virginianus) in a North American zoo. The clinical signs and histopathological lesions in these deer were typical of MCF. Antibody to an epitope conserved among the MCF viruses was detected in the sera collected from the deer. PCR failed to amplify viral sequences from DNA extracted from peripheral blood leukocytes (PBL) and/or spleens of the deer with primers specific for ovine herpesvirus 2 (OHV-2) or specific for alcelaphine herpesvirus 1 (AHV-1). By using degenerate primers targeting a conserved region of a herpesviral DNA polymerase gene, a DNA fragment was amplified from the PBL or spleens of all six deer and sequenced. Alignment of the sequences demonstrated that the virus in the deer belongs to the Gammaherpesvirinae subfamily, exhibiting 82% identity to OHV-2, 71% to AHV-1, and 60% to a newly identified bovine lymphotropic herpesvirus. This virus, which causes classical MCF in white-tailed deer, is a newly recognized agent belonging to the MCF group of gammaherpesviruses. It is the third reported pathogenic MCF virus, genetically distinct but closely related to OHV-2 and AHV-1. The reservoir for the virus has not been identified.

Amino Acid Sequence↗
PubMed2000

Neuropsychological differentiation of depression and anxiety.

The high comorbidity of depression and anxiety is well established empirically but not well understood conceptually, in terms of either psychological or biological mechanisms. A neuropsychological model of regional brain activity in emotion provides contrasting hypotheses for depression and anxiety, with depression associated with a relative decrease and anxiety with a relative increase in right-posterior activity. These hypotheses received support in a comparison of individuals diagnosed with depression and community controls, and also in a separate study of nonpatients administered a measure of perceptual asymmetry. Hierarchical regressions revealed that depression and anxiety were uniquely and jointly associated with perceptual asymmetry. In light of consistent empirical support for the model, implications for conceptualizations of the comorbidity of depression and anxiety are discussed.

Adult↗
PubMed2000

C3: A comprehensive physician activity and billing tool

Purpose: The Clinical Charge Capture system (C3) was developed at the University of Michigan to increase the efficiency and accuracy with which information about physician activity and billing is tracked in academic medical centers. Description: This Oracle-based, Visual Basic system integrates the operating room scheduling system, transcription database, clinical data repository, referring physician database, and IDX to allow physicians and staff to perform paperless and on-line standard tasks such as preauthorizing procedures; creating a bill which describes the charges for procedures performed along with their supporting diagnoses; identifying inpatient daily care and consult charges; dictating, editing, signing, and providing attestations for procedural and inpatient notes (menu-driven boilerplate notes are used for common procedures); submitting of charges on-line to IDX; and downloading of payment data from IDX. A messaging system between physicians and billing specialists allows questions to be posed regarding coding issues and options. Summary information about charges is presented and the status of the bill as it progresses through the internal review and billing process is demonstrated. Any missing data are flagged such that delivery of a bill is accurate, timely, and complete. Outpatient clinic visit charges are acquired on line using bar code technology with direct download of clinic charges to IDX. Generation of charges and referral letters may be performed immediately following the performance of a procedure or patient encounter or subsequently in the office. Resident activity is also tracked. Finally, search functions are provided which allow the program to serve as a clinical information research database. Results: The time to bill submission for operative procedures in fiscal year 1996 (Pre-C3) when compared to 1999 (Post-C3) decreased in each individual surgical division (See figure)as well as for the overall Department (Total: mean Pre-C3=40 days, mean Post-C3=8 days). The average bill was increased by 9% for each primary charge submitted. Conclusions: We conclude that this system has the potential to enhance the efficiency, accuracy, and organization of routine physician documentation, billing, and data collection activities.

Journal Article↗
PubMed1999

Anaerobic phosphate release from activated sludge with enhanced biological phosphorus removal. A possible mechanism of intracellular pH control

The biochemical mechanisms of the wastewater treatment process known as enhanced biological phosphorus removal (EBPR) are presently described in a metabolic model. We investigated details of the EBPR model to determine the nature of the anaerobic phosphate release and how this may be metabolically associated with polyhydroxyalkanoate (PHA) formation. Iodoacetate, an inhibitor of glycolysis, was found to inhibit the anaerobic formation of PHA and phosphate release, supporting the pathways proposed in the EBPR metabolic model. In the metabolic model, it is proposed that polyphosphate degradation provides energy for the microorganisms in anaerobic regions of these treatment systems. Other investigations have shown that anaerobic phosphate release depends on the extracellular pH. We observed that when the intracellular pH of EBPR sludge was raised, substantial anaerobic phosphate release was caused without volatile fatty acid (VFA) uptake. Acidification of the sludge inhibited anaerobic phosphate release even in the presence of VFA. From these observations, we postulate that an additional possible role of anaerobic polyphosphate degradation in EBPR is for intracellular pH control. Intracellular pH control may be a metabolic feature of EBPR, not previously considered, that could have some use in the control and optimisation of EBPR. Copyright 1999 John Wiley & Sons, Inc.

Journal Article↗
PubMed1999

Basic fibroblast growth factor enhances axonal sprouting after cortical injury in rats.

The trophic factors responsible for initiating and guiding the outgrowth of axons have proven to be elusive throughout most of this century. Entorhinal cortex injury, which denervates the hippocampal formation of rats, induces axonal sprouting by several surviving hippocampal afferents and results in a significant elevation of growth factors, one of which is basic fibroblast growth factor (bFGF). The possibility that bFGF may regulate lesion-induced hippocampal sprouting was examined by making i.v. bFGF infusions into rats with unilateral entorhinal lesions. Basic FGF treatment significantly increased sprouting by the cholinergic septodentate pathway. Thus, the increase in bFGF following central nervous system injury may signal its role in the regulation of injury-related axonal remodeling of a cholinergic pathway.

Animals↗
PubMed1999

Automatic karyotyping of metaphase cells with overlapping chromosomes.

Image analysis research aimed at analyzing images of banded, human chromosomes is described. An experimental automated karyotyping system (AKS) has been assembled. The goal of the system is to label the chromosomes from a metaphase image with minimal human intervention. The AKS is unique in that it is designed to automatically process cells containing overlapping chromosomes. It also has four novel algorithmic features: the use of cross section sequence graphs, an over-segmentation-based segmentation strategy, the use of the 'pale path' concept for banded chromosomes and the application of mathematical programming for cell-level chromosome classification in cells with overlapping chromosomes. System performance was analyzed using a variety of metaphase images exhibiting various levels of overlapping chromosomes.

Algorithms↗
PubMed1999

Converging evidence for a cognitive anomaly in early psychopathology.

Subcomponents of the N200 component of the event-related brain potential believed to be differentially sensitive to involuntary and voluntary cognitive processes were examined. Nonpatients (N = 131) identified initially by the Chapman and Depue research scales and classified later on the basis of diagnostic symptom clusters and family psychiatric history provided converging evidence for an intact mismatch negativity subcomponent. In contrast, the N2b subcomponent distinguished several groups of subjects. Results suggested abnormal voluntary cognitive processing, perhaps reflecting compensatory efforts in subjects at risk for or manifesting psychopathology, particularly those showing negative symptoms.

Adolescent↗
PubMed1999

Pancreatic enzymes: secretion and luminal nutrient digestion in health and disease.

Severe pancreatic exocrine insufficiency leading to malabsorption of nutrients is one of the most important late features of chronic pancreatitis. In contrast to other key enzymes, pancreatic synthesis and secretion of lipase is impaired more rapidly, its intraluminal survival is shorter due to its higher susceptibility against acidic and proteolytic denaturation, and its luminal digestive action is hardly compensated by nonpancreatic mechanisms. As a consequence, steatorrhea is in general more severe and occurs several years before clinical malabsorption of protein or starch. Apart from the detrimental effects of nutrient deficiency, profound alterations of upper gastrointestinal secretory and motor functions may be an additional and hitherto underestimated consequence of increased nutrient delivery to distal intestinal sites. Effective reduction of nutrient malabsorption in pancreatic insufficiency requires delivery of sufficient enzymatic activity into the duodenal lumen simultaneously with meal nutrients. Modern enteric-coated pancreatin microsphere preparations attempt to achieve this by optimizing the size of individual microspheres and chemical properties of the coating. However, lipid digestion cannot be completely normalized in most patients by current standard therapy. In the future, acid and protease stable bacterial and fungal lipases with additional pH optima in the acidic milieu or animal or bioengineered human gastric lipase preparations may offer superior therapeutic alternatives. This review first summarizes current knowledge about secretion and luminal fate of pancreatic enzymes and their effects on nutrient digestion in health and chronic pancreatitis. Second, rationale, current standards, options, and future aspects of enzyme replacement therapy are discussed.

Amylases↗
PubMed1999

Identification of some of the major groups of bacteria in efficient and nonefficient biological phosphorus removal activated sludge systems.

To investigate the bacteria that are important to phosphorus (P) removal in activated sludge, microbial populations were analyzed during the operation of a laboratory-scale reactor with various P removal performances. The bacterial population structure, analyzed by fluorescence in situ hybridization (FISH) with oligonucleotides probes complementary to regions of the 16S and 23S rRNAs, was associated with the P removal performance of the reactor. At one stage of the reactor operation, chemical characterization revealed that extremely poor P removal was occurring. However, like in typical P-removing sludges, complete anaerobic uptake of the carbon substrate occurred. Bacteria inhibiting P removal overwhelmed the reactor, and according to FISH, bacteria of the beta subclass of the class Proteobacteria other than beta-1 or beta-2 were dominant in the sludge (58% of the population). Changes made to the operation of the reactor led to the development of a biomass population with an extremely good P removal capacity. The biochemical transformations observed in this sludge were characteristic of typical P-removing activated sludge. The microbial population analysis of the P-removing sludge indicated that bacteria of the beta-2 subclass of the class Proteobacteria and actinobacteria were dominant (55 and 35%, respectively), therefore implicating bacteria from these groups in high-performance P removal. The changes in operation that led to the improved performance of the reactor included allowing the pH to rise during the anaerobic period, which promoted anaerobic phosphate release and possibly caused selection against non-phosphate-removing bacteria.

Bacteria↗
PubMed1998

[Significance of galenic preparations for luminal release of 5-aminosalicylic acid in human small intestinal lumen].

BACKGROUND: Sufficient intraluminal concentrations of 5-aminosalicylic acid (ASA) within inflamed regions of the intestine are required for therapeutic efficacy in inflammatory bowel disease. Various oral delayed release preparations have been developed to ensure that 5-ASA is set free in those parts of the gut, which are most frequently affected. However, resulting intraluminal concentrations within the small bowel are unknown. Therefore, we determined and compared 5-ASA release within different segments of the small bowel from an Eudragit L coated 5-ASA preparation (Salofalk) and from an ethylcellulose coated microsphere preparation (Pentasa). METHODS: Twelve healthy subjects were intubated with an oro-ileal multilumen-tube for marker perfusion, duodenal, jejunal and ileal aspiration of chyme and intestinal manometry. Each subject received 500 mg 5-ASA (Salofalk, n = 6, or Pentasa, n = 6) together with a semiliquid test meal. Intestinal aspirates, blood and urine samples were obtained in regular intervals for 7 to 10 hours and were analysed for 5-ASA and its main metabolite acetyl-5-ASA by HPLC. RESULTS: With Salofalk, gastric emptying of 5-ASA did not take place in the digestive, but in the subsequent interdigestive period. Luminal delivery of 5-ASA and acetyl-5-ASA increased from the duodenum (3% of dose) to the ileum (30% of dose). 10% of the dose administered were excreted in urine and about 90% reached the colon unreleased or solubilised. By contrast, with Pentasa, 5-ASA was delivered to the duodenum together with the test meal and released continuously throughout the small intestine (about 20% of dose solubilised at each intestinal site). Only 3.5% of the dose administered were excreted in urine. Deliver of 5-ASA to the colon was equal to Salofalk. CONCLUSIONS: From both preparations, considerable amounts of 5-ASA are released during small intestinal transit thus explaining therapeutic efficacy in small intestinal Crohn's disease. Because of specific release patterns, Salofalk may be of use especially in terminal ileal disease, where as patients with extensive small intestinal disease including the proximal small intestine might benefit from Pentasa.

Biological Availability↗
PubMed1998

The Caenorhabditis elegans SH2 domain-containing protein tyrosine phosphatase PTP-2 participates in signal transduction during oogenesis and vulval development.

Src homology-2 (SH2) domain-containing protein tyrosine phosphatases (SHPs) have been identified as either positive or negative regulators of signaling events downstream of receptor protein tyrosine kinases (R-PTKs). We describe here our characterization of ptp-2, a Caenorhabditis elegans gene that encodes a 668-amino-acid SHP. We isolated a recessive ptp-2 loss-of-function allele, op194, that lacks the conserved protein tyrosine phosphatase catalytic domain by screening for transposon-mediated deletion mutations. Homozygous ptp-2(op194) hermaphrodites exhibit a completely penetrant zygotic semisterile/maternal effect lethal phenotype, characterized by the presence of abnormally large oocytes in the zygotic semisterile animals. These phenotypes indicate that PTP-2 activity is essential for proper oogenesis. Gain-of-function let-60 ras alleles rescued the defects associated with ptp-2(op194), suggesting that LET-60 Ras acts downstream of, or in parallel to, PTP-2 during oogenesis. Although ptp-2 function is not required for normal vulval development, ptp-2(op194) altered significantly the vulval phenotypes caused by mutations in several genes of the inductive signaling pathway. The penetrance of the multivulva phenotype caused by loss-of-function mutations in lin-15, and gain-of-function mutations in let-23 or let-60 ras, was reduced by ptp-2(op194). Moreover, ptp-2(op194) increased the penetrance of the vulvaless phenotype conferred by a weak loss-of-function sem-5 allele. Taken together, our genetic data positions PTP-2 activity downstream of LET-23 in the vulval induction signaling pathway. Although PTP-2 functions to transmit a requisite signal during oogenesis, PTP-2 function during C. elegans vulval cell differentiation appears to be directed at regulating the overall strength of the inductive signal, which may contribute to the quantitative differences in signaling required for the proper specification of the 1 degrees , 2 degrees , and 3 degrees vulval cell fates.

Alleles↗