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Biomedical subjects

C Brown

Publications and source records attributed to C Brown.

At least 343 records · Page 19Linked to original sources
PubMed1991

The American College of Rheumatology criteria for the classification and reporting of osteoarthritis of the hip.

Clinical criteria for the classification of patients with hip pain associated with osteoarthritis (OA) were developed through a multicenter study. Data from 201 patients who had experienced hip pain for most days of the prior month were analyzed. The comparison group of patients had other causes of hip pain, such as rheumatoid arthritis or spondylarthropathy. Variables from the medical history, physical examination, laboratory tests, and radiographs were used to develop different sets of criteria to serve different investigative purposes. Multivariate methods included the traditional "number of criteria present" format and "classification tree" techniques. Clinical criteria: A classification tree was developed, without radiographs, for clinical and laboratory criteria or for clinical criteria alone. A patient was classified as having hip OA if pain was present in combination with either 1) hip internal rotation greater than or equal to 15 degrees, pain present on internal rotation of the hip, morning stiffness of the hip for less than or equal to 60 minutes, and age greater than 50 years, or 2) hip internal rotation less than 15 degrees and an erythrocyte sedimentation rate (ESR) less than or equal to 45 mm/hour; if no ESR was obtained, hip flexion less than or equal to 115 degrees was substituted (sensitivity 86%; specificity 75%). Clinical plus radiographic criteria: The traditional format combined pain with at least 2 of the following 3 criteria: osteophytes (femoral or acetabular), joint space narrowing (superior, axial, and/or medial), and ESR less than 20 mm/hour (sensitivity 89%; specificity 91%). The radiographic presence of osteophytes best separated OA patients and controls by the classification tree method (sensitivity 89%; specificity 91%). The "number of criteria present" format yielded criteria and levels of sensitivity and specificity similar to those of the classification tree for the combined clinical and radiographic criteria set. For the clinical criteria set, the classification tree provided much greater specificity. The value of the radiographic presence of an osteophyte in separating patients with OA of the hip from those with hip pain of other causes is emphasized.

Hip Joint↗
PubMed1991

Reversal of Hartmann's procedure: timing and operative technique.

A review of closure of Hartmann's colostomy was undertaken to establish guidelines for the timing and technique of reversal. Between 1984 and 1990 there were 69 reversals; 48 patients originally had diverticular disease and 21 had carcinoma. One-third underwent reversal before 4 months and two-thirds after this time. The operative mortality rate was 3 per cent and the anastomotic leak rate 4 per cent. Significant morbidity occurred in 30 per cent. There was no advantage in delayed closure. Complications occurred in 24 per cent of patients undergoing reversal before and 35 per cent undergoing reversal after 4 months. Thirty-five anastomoses were hand-sewn and 34 stapled. There were no differences in operating time for the two techniques, but a greater number were stapled after 4 months than before (P less than 0.05), which may reflect increased rectal stump shrinkage with time. There were no differences in complication rates whether the anastomosis was hand-sewn (34 per cent) or stapled (26 per cent). Closure of Hartmann's colostomy is a safe procedure but has a significant morbidity in nearly one-third of cases. On the basis of these results, there is no indication to delay closure after 4 months have elapsed, and earlier reversal, when the rectal stump is most accessible, is recommended.

Anastomosis, Surgical↗
PubMed1991

Growth and differentiation of primary tracheal epithelial cells in culture: regulation by extracellular calcium.

Growth and differentiation of primary monkey tracheal epithelial (MTE) cells maintained on collagen gel substrata were studied in a defined serum-free culture medium containing 0.03 to 3.0 mM extracellular calcium. Cell attachment efficiency (40-60%) was not altered by different calcium levels. Growth of primary MTE cells on collagen gel substrata, which was vitamin A dependent, was enhanced 50% in the medium supplemented with high calcium (greater than 0.3 mM). High calcium medium also increased cell-cell interactions, formation of desmosomes, and multi-cell layering. The relative content of mucous cells, which were identified by a mucin-specific monoclonal antibody and the presence of mucus-secreting granules at the ultrastructural level, was greater in the high-calcium medium. Furthermore, the secretion of mucin into the medium, determined either by an ELISA or by the incorporation of 3H-glucosamine into mucous glycoprotein fractions, was also increased more than 5-fold in media containing high calcium content (greater than 0.6 mM). In contrast, MTE cells cultured in low calcium medium (less than 0.15 mM) were squamous-like with prominent tonofilaments, and their secretory product was mainly hyaluronate. These results demonstrate that media containing a high calcium content promote conducting airway epithelium to express mucous cell differentiation, while media with low calcium content promote squamous cell differentiation.

Animals↗
PubMed1991

Comparative analysis of nucleotide sequences of the partial envelope gene (5' domain) among human T lymphotropic virus type I (HTLV-I) isolates.

Human T-cell lymphotropic virus type I (HTLV-I) is associated with adult T-cell leukemia/lymphoma (ATL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The nucleotide sequences of 640 bp of the proviral genome (positions 5158-5797) derived from 11 HTLV-I-infected persons were analyzed using the polymerase chain reaction and M13-based sequencing techniques. Patterns of single nucleotide substitutions were characterized from the extracellular domain of the envelope gene (gp46). Compared with other retroviruses, the nucleotide sequences of the HTLV-I external envelope gene are highly conserved among the genotypes studied. We found no evidence of dual infections with HTLV-II among the seropositive asymptomatic persons or in patients with either ATL or HAM/TSP. No unique sequence differences were observed in the envelope gene of the HTLV-I isolates derived from patients coinfected with human immunodeficiency virus type 1 (HIV-1). However, comparative analysis of these data and other published HTLV-I envelope sequences indicated the presence of four subtypes of HTLV-I in relation to their geographic origin.

Base Sequence↗
PubMed1991

Physiologic and subjective effects of respirator mask type.

The effect of alternate airflow path designs on full-face mask air-purifying respirators was assessed in 14 healthy volunteers during submaximal exercise. Respirator designs included no respirator (N), full-face mask, dual-cartridge with no nasal deflector (FN), full-face mask respirator with nasal deflector (FD), and a powered air-purifying respirator (PA). Physiologic effects were measured by using respiratory inductive plethysmography and subjective responses by two visual analog scales. There were significant effects of airflow path design upon the physiologic parameters of ventilation, tidal volume, and mean flow rate. There were no significant physiologic or subjective differences between the full-face mask respirators with and without the nasal deflector in place. The PA had less physiologic impact than the nonpowered models but did not show significant subjective benefit. The study suggests that both subjective and objective physiologic responses must be utilized in assessing respirator design.

Adult↗
PubMed1991

Evidence of marked sexual behavior change associated with low HIV-1 seroconversion in 149 married couples with discordant HIV-1 serostatus: experience at an HIV counselling center in Zaire.

To determine the effect of an HIV-1 counselling program on 149 married Zairian couples with discordant HIV-1 serology, the rates of HIV-1 seroconversion and reported condom utilization have been observed during 382.4 person-years of follow-up (minimum follow-up time per couple of 6 months). Before determination of HIV-1 serostatus and counselling, less than 5% of these couples had ever used a condom. One month after notification of HIV-1 serostatus and counselling, 70.7% of couples reported using condoms during all episodes of sexual intercourse. At 18 months follow-up, 77.4% of the 140 couples still being followed reported continued use of condoms during all episodes of sexual intercourse. At the time of notification of HIV-1 serostatus, 18 couples experienced acute psychological distress. Home-based counselling by trained nurses resolved these difficulties in all but three couples who subsequently divorced. Intensive counselling following notification of HIV-1 serostatus led to low rates of HIV-1 seroconversion (3.1% per 100 person-years of observation) in Zairian married couples with discordant HIV-1 serostatus who voluntarily attended an HIV counselling center.

Adult↗
PubMed1991

Prevalence of HIV-1 p24 antigenemia in African and North American populations and correlation with clinical status.

Sera from 622 individuals and culture supernatants from three HIV-1 viral isolates were assayed for HIV-1 p24 antigen to investigate the frequency of p24 antigenemia in African and North American populations using three commercial HIV-1 p24 antigen assays (Coulter, Du Pont, and Abbott). The prevalence of p24 antigenemia in 89 hospitalized Zairian AIDS patients was significantly lower than in 47 clinically comparable AIDS patients in the USA (17 versus 48%, P less than 0.0001). Prevalence of p24 antigenemia in sera from 200 asymptomatic HIV-1-infected individuals was also lower in individuals from Zaire compared with 83 individuals in the USA (3.5 versus 7%). In African individuals, antigenemia prevalence increased with advanced clinical status: 8% in ambulatory AIDS patients, 17% in hospitalized AIDS patients and 18% in postmortem AIDS patients. Acid hydrolysis treatment of sera from 63 Zairian AIDS patients initially negative for p24 antigen showed an 11% positivity rate confirmed by neutralization, suggesting that immune complexing of p24 antigen may play a role in the observed lower p24 antigenemia rates reported for African individuals.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Vitronectin: effects on keratinocyte motility and inhibition of collagen-induced motility.

Epibolin, a plasma protein, was initially purified on the basis of its ability to enhance spreading of keratinocytes. It is now known that epibolin is identical to serum spreading factor, S protein, and vitronectin, and the current name for the protein is vitronectin. Studies of vitronectin on cultured keratinocytes showed that it caused spreading and epiboly but not cellular adhesion to the substratum. In studies with other types of cells, vitronectin increased migration of several types of cells in a Boyden chamber. Because some agents that enhance spreading and adhesion, such as collagen and fibronectin, also increase motility, we tested whether vitronectin increased motility of keratinocytes. By photographing and quantitating motility of keratinocytes plated on a bed of colloidal gold particles, we determined that vitronectin increased local movement of keratinocytes in a concentration-dependent fashion, resulting in clearing of gold particles in a circular pattern around the cells, but did not cause the production of tracks found in cultures plated on collagen or fibronectin. The small increases in clearing of the gold particles that occurred in the presence of vitronectin were abolished by antibody to vitronectin. Furthermore, the marked increase in motility produced by type I collagen was significantly reduced when the keratinocytes were treated with vitronectin. Antibody to vitronectin also abrogated the vitronectin-induced reduction in collagen-stimulated motility, confirming that this action was specific for vitronectin. Serum, which contains vitronectin, stimulated motility in a fashion identical to purified vitronectin, but serum lacking vitronectin was inactive. These studies show that vitronectin causes a localized increase in movement associated with spreading resulting in a halo around individual cells, that vitronectin does not enhance directional motility of keratinocytes in this assay but in contrast antagonizes such motility produced by collagen, and that vitronectin is the factor in serum responsible for this effect. The findings with vitronectin and collagen show that these agents stimulate different types of motility. The roles in wound healing of agents stimulating different types of motility are unclear and require further study.

Blood Physiological Phenomena↗
PubMed1991

Correlation between dermal interstitial immunoglobulin G and hypergammaglobulinemia.

The diffuse dermal immunofluorescence (DDIF) observed in human skin biopsies that is produced by fluorochrome-conjugated antisera reactive with human immunoglobulin G (IgG) has commonly been viewed in the past as an artifact of direct immunofluorescence microscopy. However, it has been our belief that DDIF, which has been observed in 14% of the biopsies processed in our laboratory, might represent an in vivo phenomenon of excess unbound dermal interstitial immunoglobulin G reflective of elevated serum IgG levels. To examine this hypothesis, we carried out a blinded prospective study of the frequency of DDIF in two groups of age- and sex-matched patients that differed with respect to the presence or absence of serum hypergammaglobulinemia (gamma globulin greater than 2.5 mg/100 ml). The subjective intensity of DDIF and the fluorescein-isothiocyanate (FITC) conjugated anti-human IgG antibody titer at which point DDIF disappeared were both compared with serum gamma globulin levels. Also, the amount of IgG that could be extracted from biopsy specimens by an overnight phosphate-buffered saline (PBS) elution procedure was quantified by solid-phase immunoassay. We noted a trend of increased DDIF intensity with increasing serum gamma globulin levels. In addition, there was a relatively weak but significant positive correlation between DDIF endpoint titers and serum gamma globulin levels (p = 0.05, r = 0.429). The strongest positive statistical correlation observed in the study was between the quantities of IgG that could be eluted from skin biopsies and serum gamma globulin levels (p = 0.01, r = 0.599). These findings suggest that DDIF is a true biologic phenomenon reflective of elevated serum gamma globulin levels and demonstrate that simple overnight elution of unbound dermal IgG can unmask the presence of disease-related, specifically-bound IgG.

Adult↗
PubMed1991

Sequence analysis and idiotypic relationships of BEG-2, a human fetal antibody reactive with DNA.

Monoclonal antibody (mAb) BEG-2 is a dsDNA binding IgM lambda derived from a 12-week human fetus. Two binding site idiotypes (BEG-2 Id alpha and BEG-2 Id beta) have been defined with the use of polyclonal rabbit anti-idiotypic anti-serum. BEG-2 Id alpha is located on the lambda light chain and has been described previously. The BEG-2 Id beta is present on the mu heavy chain. By means of a direct binding ELISA, BEG-2 Id beta has been identified on EBV-derived mAbs from human fetal liver or spleen (5%), human cord blood (2.7%) and adult peripheral blood (1%). In addition, the Id is present on 8.5% of adult spleen-derived hybridoma antibodies and 6% of RA synovium-derived hybridoma antibodies. In all populations the presence of the Id is strongly associated with binding to DNA and other polyanions. Competition assays indicated that the Id was located at or near the antigen-binding site on these molecules. To explore the structural basis of this binding, a major part of the BEG-2 heavy chain was sequenced and found to be encoded by a member of the VH4 family joined to a variant of JH5 by a very short Diversity or N region. Of the BEG-2 Id beta positive mAbs for which the VH family has been determined, five are encoded by VH4 and two are encoded by VH6, but none is encoded by other families. Thus, the BEG-2 Id beta identifies a set of polyreactive antibodies that are common in fetal life, persist into adulthood and are encoded by VH6 and, a subset of VH4 genes.

Amino Acid Sequence↗
PubMed1991

Corticotropin-releasing factor modulates the immune response to stress in the rat.

We examined the role of CRF, a key mediator of the endocrine response to stress, in modulating immunosuppression during the subacute stress of intermittent electrical shock over 1 h. Administration of shock to intact rats resulted in a 74% decrement in T-lymphocyte proliferation and a 59% decrease in natural killer cytotoxicity. Similar suppression of these two parameters of immune function in response to shock was noted in adrenalectomized rats as well. The immunosuppressive effects of this shock were significantly and comparably blunted when both intact and adrenalectomized animals were pretreated 1) iv with either a highly potent polyclonal CRF antibody or a specific CRF antagonist or 2) intracerebroventricularly with either a high affinity monoclonal antibody to CRF or a specific CRF antagonist. An immunomodulatory role for CRF is further supported by the findings that administration of exogenous CRF, either iv (10 micrograms/animal) or intracerebroventricularly (1 microgram/animal), resulted in significant decrements in lymphocyte proliferation and natural killer cytotoxicity, similar to those seen with the stress paradigm. Our observations indicate that CRF plays a significant role in modulating the immune response to subacute stress, largely by adrenal-independent mechanisms.

Adrenalectomy↗
PubMed1991

In-house CT program development.

"Accomplishing in-house CT maintenance can be a lengthy process," warns the author speaking from his own experience at the Department of Veterans Affairs Medical Center, Philadelphia, Pennsylvania. However, Mr. Brown insists that the payoff can be substantial in terms of significant cost savings and decreased downtime. His step-by-step advice and documentation are structured to help managers interested in investigating this option.

Cost-Benefit Analysis↗
PubMed1991

Personal financial strategies.

Personal and professional characteristics should be considered when planning a financial future. Analyzing income, expenses, net worth, investments, insurance, and taxes are important for sound financial health.

Financial Management↗
PubMed1991

Evaluation of intravenous administration of concentrated immunoglobulin G to colostrum-deprived foals.

Ten foals of various breeds were deprived of colostrum from birth to 36 hours of age, then were allotted to 2 groups. Foals of group 1 (n = 6) were given 20 g (200 ml) of purified equine IgG IV in a 10% solution, and foals of group 2 (n = 4) were given 30 g (300 ml) of the same preparation. Total administration time for each 10 g of IgG in 100 ml was approximately 10 minutes. Serum IgG concentration in foals was assessed prior to, between 24 and 48 hours, and at 7 and 14 days after IgG administration. Between 24 and 48 hours after IgG administration, mean serum IgG concentration in group-1 foals was 425 mg/dl (range, 350 to 480 mg/dl). Mean body weight for this group of foals was 50.3 kg (range, 43.3 to 54.7 kg). For group-2 foals, mean serum IgG concentration was 768 mg/dl (range, 640 to 920 mg/dl) between 24 and 48 hours after administration of IgG. Foals of this group had mean body weight of 43.2 kg (range, 36.5 to 47.5 kg). Serum IgG concentration in group-2 foals at 24 to 48 hours was significantly (P = 0.005) greater than that in group-1 foals. Mean total IgG recovery at 24 to 48 hours, calculated on the basis of 94.5 ml of plasma volume/kg of body weight, was approximately 100%. Values of IgG measured in all foals 1 and 2 weeks after administration of the IgG concentrate were equivalent to values expected after normal decay of passively acquired IgG.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

HIV-1 seropositivity and mortality at University Hospital, Kinshasa, Zaire, 1987.

This study examines the impact of HIV-1 infection and AIDS on 500 of 563 consecutive deaths at University Hospital, Kinshasa, Zaire, in late 1987. HIV-1 seroprevalence was 31% for the entire population and 43% for the 247 adults. Forty-two (38%) of the 110 HIV-1-seropositive adult deaths occurred in those between the ages of 25 and 34 years. The mean age of death for seropositives was 36 years, 7.5 years less than seronegative deaths. AIDS and AIDS-associated diagnoses such as cryptococcal meningitis, chronic diarrhea and pneumonia accounted for 42% of all adult deaths and 74% of all HIV-1-seropositive adult deaths. Seventeen per cent of 50 sera initially negative by enzyme-linked immunosorbent assay (ELISA) were ultimately found to be HIV-1-seropositive by Western blot or p24 antigen testing. The data indicate that HIV-1 infection and AIDS contribute significantly to adult mortality in Kinshasa population and that sensitivity of ELISA tests decreases in terminal HIV-1 infection.

Acquired Immunodeficiency Syndrome↗