Search PubMed⌕ Search

Biomedical subjects

M L Collins

Publications and source records attributed to M L Collins.

At least 37 records · Page 2Linked to original sources
PubMed1997

Effect of interferon-alpha and ribavirin therapy on serum GB virus C/hepatitis G virus (GBV-C/HGV) RNA levels in patients chronically infected with hepatitis C virus and GBV-C/HGV.

GB virus C/hepatitis G virus (GBV-C/HGV) is a newly described virus associated with hepatitis in humans, and GBV-C/HGV coinfection is common in patients chronically infected with hepatitis C virus (HCV). To determine the clinical impact of GBV-C/HGV infection in such patients and the effect of interferon-alpha and ribavirin therapy on serum GBV-C/HGV RNA levels, GBV-C/HGV RNA was detected and quantitated in serum samples from 62 chronically infected HCV patients by a combination of a qualitative nested reverse transcription-polymerase chain reaction and a newly developed quantitative branched DNA assay: 10 patients were positive for serum GBV-C/HGV RNA. There were no differences in the clinical, biochemical, and histologic features of the patients with GBV-C/HGV-HCV coinfection compared with those with HCV infection alone. Interferon-alpha treatment caused a marked but usually transient reduction in serum GBV-C/HGV RNA, and ribavirin had, at most, a modest antiviral effect.

Adult↗
PubMed1997

Iris juvenile xanthogranuloma studied by immunohistochemistry and flow cytometry.

An unusual large tan iris mass in a 19-month-old child was removed by iridocyclectomy and studied by light microscopy, immunohistochemistry, and flow cytometry. The excised mass consisted of granulomatous inflammation with numerous osteoclast-like giant cells and scattered atypical Touton giant cells. Immunohistochemistry studies showed that the cells were most consistent with mononuclear histiocytes. Flow cytometry showed that 90% of the cells sampled were T-lymphocytes, with a predominance of T-suppresser cytotoxic cells. Juvenile xanthogranuloma (XG) of the iris can occur as a large solitary mass, without signs of intraocular inflammation or hyphema.

Biomarkers↗
PubMed1997

Hepatitis C virus: quantitation and distribution in liver.

The optimal method for viral quantitation and the most appropriate site for determining viral load in patients with chronic hepatitis C virus (HCV) infection are unknown. We developed a method for measuring HCV RNA in the liver with the following features: 1) efficient extraction of RNA from tissue (89% of RNA recovered); 2) accurate amplification using branched DNA with strong concordance between a single sample tested on multiple occasions either in the same or in different runs; 3) good sensitivity (95%) and specificity (100%). HCV RNA was detected in as little as 2 mg of tissue, and viral load determined in a needle biopsy was representative of viral load in other parts of the liver. Within individual livers, 68% of the samples quantitated were within 1.5-fold of the geometric mean, and 95% were within 2.2-fold of the geometric mean. The mean ratio of virus in the liver and serum was 103, range 17.4-286. A delay of 30 minutes before freezing the liver tissue resulted in a reduction in the measured viral load in some, but not all instances. A sensitive, specific and reproducible method for quantitating HCV RNA in the liver has been developed. Measurement of viral load at one site was representative of viral load at other sites. While hepatic HCV RNA levels are consistently greater than serum levels, the ratio of liver of serum viral load varies widely. The clinical use of measurement of viral load in the liver remains to be defined.

Adult↗
PubMed1996

Hepatitis C virus RNA quantification in right and left lobes of the liver in patients with chronic hepatitis C.

Quantification of hepatitis C virus RNA in liver tissue is likely to be useful in the study of the natural history, pathogenesis, progression and treatment of hepatitis C virus-associated liver disease. Quantitative measurements of hepatitis C virus RNA in liver biopsy samples using the branched DNA (bDNA) signal amplification assay were carried out. The aims of this study were threefold: first, to assess the level of hepatitis C virus RNA in biopsy samples from the right and left lobes of the liver; second, to evaluate the correlation between hepatitis C virus RNA levels in serum and liver; and third, to investigate the relationship between serum and liver hepatitis C virus RNA levels and the severity of hepatic histology in non-cirrhotic patients with chronic hepatitis C. There was a strong correlation (r = 0.92, P < 0.01) between hepatitis C virus RNA levels in the right and left lobes of the liver as well as a strong correlation between hepatitis C virus RNA levels in liver and serum (r = 0.82, P < 0.01). However, there was no significant correlation between the severity of hepatic histology and levels of hepatitis C virus RNA in serum and liver among patients with chronic active hepatitis classified according to Knodell's hepatic activity index (KI). Our results indicate that hepatitis C virus RNA quantification from a single liver biopsy is representative of both lobes in patients with chronic hepatitis, and suggest that serum hepatitis C virus RNA levels are a meaningful reflection of hepatitis C virus RNA levels in the liver.

Adult↗
PubMed1996

In search of effective programs to address students' emotional distress and behavioral problems part III: student assessment of school-based support groups.

Emotional distress and behavioral problems are common in high schools. This report describes the efficacy of an in-school program based on participation in volunteer-facilitated peer support groups in addressing these problems. Two hundred and fifty students who experienced such problems participated in weekly 50-minute peer support groups led by adult nonmental health professional volunteers. The students anonymously evaluated their progress and program acceptability using an instrument developed specifically to evaluate the group experience. Analysis of the evaluation of the 131 respondents documented the reliability of a proposed Self-Assessment Questionnaire which showed that participation led to improvement in school, interpersonal, and internal domains. The program was highly accepted and showed other signs of success: half of the alcohol and substance users reduced their intake, and 60% of those who considered dropping out of school continued their education. The results provide preliminary evidence that peer support groups show promise as an economical and well-accepted method for early recognition and management of emotional and behavioral problems in high schools. For some adolescents, these groups may be the only acceptable or available therapeutic modality.

Adolescent↗
PubMed1995

Preparation and characterization of RNA standards for use in quantitative branched DNA hybridization assays.

RNA standards were developed for use in quantitative hybridization assays such as the Quantiplex HCV RNA Assay and Quantiplex HIV RNA Assay, which are based on branched DNA signal amplification. In vitro transcripts ranging in size from 0.5 to 9.4 kb were prepared and purified by phenol extraction following gel electrophoresis or column chromatography. Aliquots of the transcripts were digested to nucleosides and phosphate and then quantified by phosphate analysis against the U.S. National Institute of Standards and Technology phosphate standard. The quantitation was checked by OD260 and by either hyperchromicity or isotopic tracer analysis. The quantitation of each lot of RNA agreed within 20% by the three methods. The reproducibility of the methods was tested by preparing a total of 13 lots of standard RNAs. The average percentage full-length RNA of the 13 lots was 82%, with a range of 59 to 97%. The standard RNAs were used to test the ability of the branched DNA hybridization assay to quantify all target RNAs accurately regardless of size or slight variations in sequence. Standard Hepatitis C virus (HCV) RNAs of 1.3, 2.2, and 3.2 kb showed that size has no detectable effect on quantitation in the branched DNA hybridization assay. Three different lots of standard 3.2-kb HCV RNA were serially diluted and quantified over a thousand-fold range in the branched DNA hybridization assay. The average signal per attomole of target varied by less than 20% among the 3 lots. Standard HCV RNA transcripts were also prepared from clones of HCV subtypes 1b and 3a to study the effects of target sequence diversity and probe design on quantitation by hybridization.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1995

In search of effective programs to address students' emotional distress and behavioral problems. Part I: Defining the problem.

This article discusses the prevalence and seriousness of emotional difficulties and behavioral problems in students, with a special focus on high school students and the obstacles they encounter when addressing these problems. The educational, psychological, and medical literature which addressed the problem over the past five years was evaluated, and 22 references were selected. It was determined that the lack of consensus on the terms used to describe the problem prevented accurate assessment of its prevalence. However, one fifth to one third of the students were found to be affected, leading to serious educational, psychosocial, and economic difficulties--and more are likely to be affected in the 1990s. Since the school and mental health systems have not been entirely successful in addressing the problem, adolescents' patterns of seeking help indicate that peer support groups can be part of the solution. It was concluded that the enormity of the problem requires a low-cost gate-keeping mechanism to facilitate early identification and intervention. Thus, school peer-support programs, if proven effective, may complement traditional mental health services in addressing adolescents' emotional distress and behavioral problems.

Adolescent↗
PubMed1995

In search of effective programs to address students' emotional distress and behavioral problems. Part II: Critique of school- and community-based programs.

Part I of this article discussed the dimensions of students' emotional distress and behavioral problems and proposed school programs to address it. This section evaluates the school- and community-based programs advocated in educational, psychological, and psychiatric journals over the past five years. Twenty-nine articles were selected, and the programs classified by location, focus, and format. Their merits and limitations based on their results are discussed. This review found that (1) some programs poorly defined the study populations; (2) emotional distress was not included as a criterion; (3) a strictly behavioral approach or narrow focus on specific populations or issues prevailed. Only four programs used emotional expression and social support; (4) outcome measures focused on specific behaviors with only one study evaluating the emotional outcome; (5) none addressed the student's acceptance of the program; (6) only five measured the outcome beyond the immediate termination of the intervention, and only to a limited degree. While the programs reviewed support the likelihood that such interventions may be helpful, definitive conclusions which can be generalized to average high school students are still lacking. Recommendations for future school-based programs are proposed.

Adolescent↗
PubMed1993

Identification and partial sequence of the BchA gene of Rhodospirillum rubrum.

The DNA sequence was determined for a region upstream of the puf operon of Rhodospirillum rubrum. A partial ORF was identified. The DNA sequence and the inferred amino acid sequences were aligned with those of bchA of Rhodobacter capsulatus and other phototrophic bacteria. Based on this alignment and genetic evidence, this ORF was identified as R. rubrum bchA, which encodes an enzyme involved in bacteriochlorophyll biosynthesis. An additional ORF was identified in the intergenic region between bchA and pufB. Sequences possibly having a role in puf expression were identified.

Amino Acid Sequence↗
PubMed1992

Localization of methanol dehydrogenase in two strains of methylotrophic bacteria detected by immunogold labeling.

Antibodies to methanol dehydrogenase purified from Methylobacterium sp. strain AM1 and Methylomonas sp. strain A4 were raised. The antibody preparations were used in indirect immunogold labeling studies. With this approach, methanol dehydrogenase was found to be preferentially localized to the periplasmic region of the methylotroph Methylobacterium sp. strain AM1 and to the intracytoplasmic membrane of the methanotroph Methylomonas sp. strain A4. Antibody cross-reactivity to other methylotrophic bacteria was detected.

Alcohol Oxidoreductases↗
PubMed1992

Aerosolized Pseudomonas elastase and lung fluid balance in anesthetized sheep.

The role of the lung epithelium in lung fluid balance was studied by ventilating anesthetized sheep with an aerosol of 20 mg of elastase from Pseudomonas aeruginosa (Ps. elastase) to increase lung epithelial permeability without affecting lung endothelial permeability or lung vascular pressures. Ps. elastase had no effect on the lung vascular pressures, the alveolar-arterial PO2 gradient (A-aPO2), the flow or protein concentration of the lung lymph, or the postmortem water volume of the lungs. The morphological alveolar flooding score in these sheep was 2.5 times the control level, but this was only marginally significant. Elevation of the left atrial pressure by 20 cmH2O alone increased the postmortem lung water volume but had no effect on A-aPO2, the alveolar flooding score, or the lung epithelial permeability assessed by the clearance of 99mTc-labeled human serum albumin. Addition of aerosolized Ps. elastase to these sheep had no effect on the total lung water volume, but it caused a redistribution of water into the air spaces, as evidenced by significant increases in the alveolar flooding score and A-aPO2 (P less than 0.01). Elevation of the left atrial pressure by 40 cmH2O without elastase caused the same response as elevation of the left atrial pressure by 20 cmH2O with elastase, except the higher pressure caused a greater increase in the total lung water volume. We conclude that alteration of the integrity of the lung epithelium with aerosolized Ps. elastase causes a redistribution of lung water into the alveoli without affecting the total lung water volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1992

Recovery following orthognathic surgery and autologous blood transfusion.

Patients undergoing maxillary surgery, with or without mandibular surgery, were divided into two groups. One surgeon's patients served as controls and did not receive blood unless hemodynamically indicated. The remaining surgeons' patients were transfused regardless of their hemoglobin levels following surgery. An attempt was made to identify benefits or complications associated with the reinfusion of autologous blood, particularly in patients with "low blood loss." Patients were asked to record when they returned to their presurgical level of activity. Of the 46 patients in the study 14 (12 nontransfused, two transfused) were not back to full activity 6 weeks after surgery. Of the 32 patients that reported a return to full activity within the study period, transfused patients reported a significantly quicker return to full activity at 2 weeks, 3 weeks, and 4 weeks postoperatively than did their nontransfused counterparts, even when blood loss at surgery was minimal. No complications have occurred with this practice.

Adolescent↗
PubMed1991

Effect of Copper on Methylomonas albus BG8.

Addition of copper to the medium for Methylomonas albus BG8 increased cell yield and methane monooxygenase activity. Intracytoplasmic membrane was formed only in cells grown with copper supplementation. Additionally, the abundances of two major membrane proteins were affected by copper in the growth medium. These findings indicate that effects of copper on the physiology of methanotrophic bacteria are not limited to those on types II and X.

Journal Article↗
PubMed1991

Construction, characterization, and complementation of Rhodospirillum rubrum puf region mutants.

Rhodospirillum rubrum is a facultatively phototrophic bacterium that, under certain growth conditions, forms an intracytoplasmic chromatophore membrane (ICM) housing the photochemical apparatus. The puf operon of R. rubrum encodes protein subunits of the photochemical reaction center and the B880 light-harvesting antenna complex. Mutant strains of R. rubrum were constructed by interposon mutagenesis through which a kanamycin resistance gene cartridge was inserted into restriction sites and in place of restriction fragments of the puf region. Southern blot analysis demonstrated that the defective copies of puf sequences had replaced their normal chromosomal counterparts through homologous recombination. The phenotypes of the mutant strains were evaluated on the basis of puf gene expression, spectral analysis, pigment content of membranes, and electron-microscopic examination of thin sections of cells grown under semi-aerobic and dark anaerobic conditions. Alterations of the puf region affect phototrophic competence and the formation of the ICM. The latter result implies an obligatory role for puf gene products in ICM formation in R. rubrum. One mutant with a deletion in puf structural genes was complemented in trans to the wild-type phenotype. Other mutants could be restored to the wild-type phenotype only by recombination.

Blotting, Northern↗
PubMed1991

Rewash bronchoalveolar lavage.

A significant limitation of standard bronchoalveolar lavage (BAL) technique is the inability to measure or calculate epithelial lining fluid (ELF) volume and, therefore, in vivo concentrations of substances in the ELF. We evaluated a new rewash BAL procedure with the radiolabeled tracer technetium pertechnetate (99mTcO4-) that theoretically should be immune to even exaggerated fluid shifts during BAL. To test this theory, we measured ELF volume in control sheep using isosmotic (280 mosm/L) hypoosmotic (140 mosm/L) and hyperosmotic (570 mosm/L) BAL solutions to induce exaggerated fluid shifts during the lavage procedure. The mean ELF volume of the lavaged lung segment was not significantly different for the three solutions (isosmotic, 1.7 +/- 0.8 ml; hypoosmotic, 1.1 +/- 1.2 ml; hyperosmotic, 2.1 +/- 1.6 ml). The slope of the 99mTcO4- disappearance curve, however, was significantly steeper for the hyperosmotic solution (-0.40 +/- 0.04%/min) compared with the other solutions (isosmotic, -0.14 +/- .01%/min; hypoosmotic, -0.12 +/- 0.07%/min). Calculation of ELF volume using sodium as an endogenous tracer gave consistently smaller values with each of the mannitol solutions (isosmotic, 0.21 +/- 0.30 ml; hypoosmotic, 0.02 +/- 0.03 ml; hyperosmotic, 0.18 +/- 0.18 ml). The failure of sodium to provide accurate estimates of the ELF volume may be due to complicated sodium movement in the lung and errors in our assumption of the initial concentration of sodium in the ELF fluid. We conclude that the rewash BAL technique with 99mTcO4- gives values of ELF volume that are not significantly affected by even exaggeration of the fluid flux that invariably accompanies BAL.

Animals↗
PubMed1990

Detection in non-erythroid cells of a factor with the binding characteristics of the erythroid cell transcription factor EF1.

The erythroid transcription factor erythroid factor-1 (EF1) plays a critical role in the transcription of erythroid-specific genes. Here we report the presence of a factor with the mobility and sequence-specific DNA-binding characteristics of EF1 at low abundance in a wide variety of non-erythroid cell types. This is the first report of an EF1-like activity in non-erythroid cells and indicates that this factor may play a role in the regulation of genes expressed in such cells.

Animals↗
PubMed1990

Optic nerve head swelling and optic atrophy in the systemic mucopolysaccharidoses.

The ocular findings in 108 patients representative of all types of mucopolysaccharidoses (MPS) were reviewed. Attention was focused on optic nerve head appearance. Optic nerve head swelling was observed in 8/14 eyes of MPS 1-Hurler (MPS 1-H); 9/21 MPS 1-Hurler-Scheie (MPS 1-H-S); 0/4 MPS I-S; 13/66 MPS II; 1/22 MPS III; 0/58 MPS IV; 5/12 MPS VI; and 2/2 MPS VII eyes. In three patients, optic nerve head swelling was present in one eye and optic atrophy in the fellow eye; in four patients, optic atrophy followed disc elevation; three patients presented with bilateral optic atrophy. It was concluded that optic nerve head swelling precedes the development of optic atrophy in the systemic MPS.

Adolescent↗