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Biomedical subjects

C Black

Publications and source records attributed to C Black.

At least 19 recordsLinked to original sources

Career differences between primary care and traditional trainees in internal medicine and pediatrics.

OBJECTIVE: To assess the relation of Primary Care Residency Training to career choice, board certification, and practice location of internists and pediatricians. DESIGN: Cohort study with up to 8 years of follow-up. SETTING: The United States. PARTICIPANTS: The 17,933 residents trained in all internal medicine (13,750) and pediatrics (4,183) residency programs between 1977 and 1982 were studied using information from the National Resident Matching Program, the AMA Physician Masterfile, the Area Resource File, and a telephone survey. MEASUREMENTS: Career choice, board certification, and practice location were studied in relation to five explanatory variables: type of residency (primary care or traditional track), gender, year of medical school graduation, educational orientation of the teaching hospital, and medical school prestige. MAIN RESULTS: Graduates of primary care residency training programs chose careers in generalist primary care significantly more often than did graduates of traditional tracks in both internal medicine (72% compared with 54%) and pediatrics (88% and 81%, respectively; P less than 0.001 for both values). Board certification rates in internal medicine were statistically higher for graduates of primary care training programs (80%) than for graduates of traditional programs (76%, P = 0.002) but were not statistically significant for both groups of pediatric graduates. Graduates of primary care programs in pediatrics and internal medicine practiced in medically less served communities more often than did graduates of traditional programs. CONCLUSION: Graduates of primary care residency training programs in internal medicine and pediatrics differ from graduates of traditional residency programs in career choices, board certification rates, and practice locations.

Career Choice

Quantitation of eosinophil Major Basic Protein cytotoxicity to rodent respiratory epithelium.

Eosinophil Major Basic Protein (MBP) may be a potent effector in damaging airway epithelium and inducing acute (2-3 h) hyperresponsiveness to agonists in primates. Accordingly, interactions between human eosinophil MBP and guinea-pig airway epithelium were quantitated biochemically. MBP was extracted from human eosinophils and purified by size-exclusion HPLC. This resulted in a single protein band on electrophoresis, which cross-reacted with antisera raised to peptides derived from the predicted sequence of human MBP. This human MBP caused modest, but statistically significant, damage to respiratory epithelium (16.4% increase in efflux of 51Cr from guinea-pig tracheal rings) after 3 h of incubation with 10(-4) M concentration, but not with lower concentrations. These data demonstrates that MBP cytotoxicity to intact epithelium can be rapidly measured in vitro, and suggests that rodent airway epithelium may be relatively resistant to the cytotoxic effects of MBP.

Animals

Activity of oxidative routes of metabolism of debrisoquin, mephenytoin, and dapsone is unrelated to the pathogenesis of vinyl chloride-induced disease.

The hypothesis, that cytochrome P4502D6, cytochrome P4502CMP, cytochrome P4503A4 or N-acetyl-transferase may form active intermediary metabolites that could be etiologically related to vinyl chloride-induced disease was investigated in 21 drug-free workers with previous development of vinyl chloride-induced disease and in 23 drug-free workers from the same plant who did not develop the syndrome. Each subject received simultaneous oral administration of debrisoquin (10 mg), mephenytoin (100 mg), and dapsone (100 mg). Measurement of the debrisoquin recovery ratio, the 8-hour recovery of 4-hydroxymephenytoin, and the dapsone recovery ratio in the subsequent 8-hour urine sample provided in vivo phenotypic indexes of cytochromes P4502D6, P4502CMP, and P4503A4 activity, respectively. An 8-hour blood sample was used to measure the acetylation ratio, a measure of N-acetyltransferase activity. The frequency distributions of each drug metabolizing activity were similar between groups. Within this small sample, there was no evidence to implicate cytochromes P4502D6, P4502CMP, and P4503A4 and N-acetyltransferase in the pathogenesis of vinyl chloride-induced disease.

Arylamine N-Acetyltransferase

Mixed connective tissue disease--goodbye to all that.

Since it was first described mixed connective tissue disease (MCTD) has been the subject of much debate. In particular the question of whether it is a truly distinctive disease entity has been challenged. It seems clear that the original description of MCTD as a mild disorder, rarely affecting the lungs or kidneys and requiring small doses of corticosteroids only, is no longer tenable. In this review a historical analysis of the clinical and serological features is presented. It is suggested that the concept of MCTD as a distinct disease entity is better replaced by the term 'undifferentiated autoimmune rheumatic/connective tissue disorder'. Many of these patients will later 'convert' into scleroderma or lupus; some will remain undifferentiated.

Autoantibodies

Reliability of skin involvement measures in scleroderma. The UK Scleroderma Study Group.

Two methods have been proposed to quantify the extent of skin involvement in scleroderma. These are (1) a scoring system which quantifies and summates this severity rating in 17 areas of skin surface and (2) a method estimating the percentage of skin involvement using a shaded manikin. We report on a study comparing the inter-observer reliability of these two approaches using the ratings of six clinicians on 12 patients. Systematic bias between observers was noted with both methods, but inter-observer agreement, as-assessed by the intraclass correlation coefficient (ICC), was higher with the score method. The manikin method resulted in a greater degree of disagreement between the observers, as well as a higher amount of random error, reflecting the difficulty of defining the bounds of abnormal skin. Despite the presence of bias, the score method is the preferred method for assessing the level of skin involvement.

Analysis of Variance

The immunogenetic background of scleroderma--an overview.

Currently it may be stated that the MHC associations in scleroderma support the classification of disease subsets, but in no ethnic group is the overall association strong enough for clinical use. In different ethnic groups, the distribution of MHC alleles varies, as does the degree of linkage disequilibrium between alleles of the linked loci. This concept is even relevant to relatively close populations. Thus Whiteside noticed that, if those patients referred from more than 100 miles from the study centre were excluded, then the strength of the DR1 association increased. The environmental contribution to scleroderma is unknown, except in the case of toxin or solvent associated disease. Different causal environmental agents found in different global regions might result in separate MHC associations and hence explain the discrepancies noted above. There are indications that associations between specific subsets of SSc patients and genetic markers will assume greater importance both diagnostically and prognostically. The lung fibrosis group look prime candidates, for example. Genetic markers are also a useful means of relating chemically-induced SSc-like disorders to the classical disease. Vinyl chloride disease provides an example. There is much heterogeneity within the disease, in terms of extent of skin involvement, severity, and of organ involvement. It is clear that the different clinical subsets of scleroderma are characterized by different associated MHC alleles. There are also many cases of clinical overlap with related diseases, and certain of these diseases have a different HLA association, which could detract from the primary HLA type associated with SSc.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibodies

A double blind, multicentre, placebo controlled trial of lornoxicam in patients with osteoarthritis of the hip and knee.

Lornoxicam is a new non-steroidal anti-inflammatory agent (NSAID) with a similar pharmacological profile to other oxicams and a potency 10 times greater than piroxicam. A multicentre, randomised, double blind, parallel group study was undertaken to compare the efficacy and tolerance of four weeks' treatment with lornoxicam (6 mg once daily, 4 mg twice daily, and 6 mg twice daily) and placebo in patients with osteoarthritis of the hip or knee. A dose related efficacy of lornoxicam was shown by the numbers of patients in each treatment group who withdrew from the trial owing to inadequate symptom relief (12/40 (30%) receiving placebo, 6/40 (15) receiving lornoxicam 6 mg daily, 4/40 (10%) receiving lornoxicam 8 mg daily, and none receiving lornoxicam 12 mg daily). This effect was confirmed by pain relief scores, which were significantly better than placebo during treatment with lornoxicam 8 mg and 12 mg daily, the effect of 12 mg daily being significantly superior to that of 8 mg daily. Similar results were obtained from functional status scores. Mean functional index (Lequesne) scores were significantly greater than placebo only at a daily dose of 12 mg lornoxicam. Lornoxicam was generally well tolerated, though some gastrointestinal side effects were seen as has been reported with other NSAIDs. Laboratory investigations showed no evidence of drug toxicity.

Administration, Oral

Urinary leukotriene E4 after lysine-aspirin inhalation in asthmatic subjects.

The FEV1 and urinary leukotriene E4 (LTE4) concentrations were determined in six aspirin-sensitive and six non-aspirin-sensitive asthmatic subjects before and after inhalation challenge with lysine-aspirin or placebo solution. Lysine-aspirin produced a mean fall in FEV1 of 26.7 +/- 4.9% (mean +/- SEM) in subjects with aspirin sensitivity and of 8.5 +/- 6.5% (mean +/- SEM) in non-aspirin-sensitive asthmatic subjects. The mean baseline urinary LTE4 concentration of 83 pg/mg creatinine (geometric mean [GM], range 15 to 326 pg/mg creatinine) in aspirin-sensitive subjects was significantly higher than the 33.8 pg/mg creatinine (GM, range 10 to 111 pg/mg creatinine) in non-aspirin-sensitive subjects (p = 0.02). In aspirin-sensitive subjects, inhalation challenge with lysine-aspirin produced a significant increase in urinary LTE4 concentration to 240 pg/mg creatinine (GM, range 60 to 1,113 pg/mg creatine), which was not observed after placebo challenge. There was no significant change in urinary LTE4 concentration after inhalation challenge with either lysine-aspirin or placebo solution in non-aspirin-sensitive asthmatic subjects. Thus, sulfidopeptide leukotrienes are released after inhalation of lysine-aspirin in aspirin-sensitive asthmatic patients.

Administration, Inhalation

Reproductive function prior to disease onset in women with scleroderma.

We tested in a retrospective study the hypothesis that women with scleroderma have an increased risk, before disease presentation, of problems in pregnancy. Reproductive history, as reported from a validated postal questionnaire, was obtained from 204 women with scleroderma [mean year of birth (yob) 1942] and compared to that reported by 233 women with primary Raynaud's phenomenon (mean yob 1948) and 189 healthy women from a population register (mean yob 1950). Only pregnancies occurring before symptom onset in the scleroderma group were considered for analysis. All analyses were adjusted for job, social class, age at first pregnancy, smoking habit, and where relevant, parity. The results are expressed as odds ratios (OR) [with 95% confidence limits (CL)] giving the risk of developing scleroderma, with previous exposure to each of the specific reproductive variables analyzed, relative to the 2 comparison groups. The women with scleroderma were more likely than the population women to have had a delay in conception (> or = 12 months): OR 2.6 (1.1, 5.7) or be infertile: OR 2.3 (0.7, 7.2). These differences were not apparent when the scleroderma group was compared to the women with Raynaud's: OR's 0.7 and 1.1, respectively. Similarly there was a greater self report of maternal ill health in pregnancy in the group with scleroderma compared to the population women: OR 2.1 (1.2, 3.5) but not compared to the women with Raynaud's: OR 1.0 (0.7, 1.6).(ABSTRACT TRUNCATED AT 250 WORDS)

Female

Expression and function of surface antigens on scleroderma fibroblasts.

Dermal fibroblasts from patients with systemic sclerosis (SSc) bound a much greater number of T lymphocytes than did normal dermal fibroblasts. Monoclonal antibodies (MAb) against classes I and II antigens of the major histocompatibility complex (MHC) and their receptors, CD8 and CD4, had no effect on T cell interaction with SSc and normal cells, while MAb against lymphocyte function-associated antigen type 3 (LFA-3) and CD2 both strongly inhibited lymphocyte attachment. MAb against intercellular adhesion molecule type 1 (ICAM-1) and LFA-1 also prevented binding of T lymphocytes, but had a more marked effect on adhesion to SSc fibroblasts than to normal fibroblasts; they also completely abolished the increased binding to fibroblasts treated with interleukin-1 alpha, tumor necrosis factor alpha, and interferon-gamma. No difference was found in the proportion of normal and SSc fibroblasts that expressed MHC classes I and II and LFA-3, but more SSc cells expressed ICAM-1, and at a higher level, than did normal fibroblasts. These results show that cultured SSc cells have elevated binding to T lymphocytes, which possibly results from expansion of a subset of fibroblasts that produces high levels of ICAM-1.

Adult

Enumeration of human peripheral blood lymphocytes secreting immunoglobulins of major classes and subclasses in healthy children and adults.

The reverse enzyme-linked immunospot assay was modified to enumerate peripheral blood mononuclear cells (PBMC) secreting IgG1-4, IgA1-2, and IgM. Anti-human IgG F(ab')2 and mouse monoclonal antibodies specific to each of the isotypes were used as solid-phase capture antibodies and developing antibodies, respectively. Although attempts were also made to detect IgD- and IgE-secreting cells (SC), their numbers in the peripheral blood were too few to be reliably estimated. The assay was applied to study healthy subjects including 21 neonates within 3 days of birth, 44 1- to 48-month-old children, and 32 adults. Sixty percent of these neonates had IgM SC in small numbers (less than 20 per 10(6) PBMC), but only three neonates had IgSC of other isotypes. In contrast, by 1-2 months of age children had IgSC of all isotypes, including IgA2 and IgG4, often in higher numbers than adults. The relative frequencies of IgSC were IgA1 greater than IgG1 greater than IgM greater than IgG2 greater than IgG3 greater than IgG4 greater than IgA2 in the children and IgA1 greater than IgG1 greater than IgA2 greater than IgM greater than IgG4 greater than IgG2 greater than IgG3 in the adults. The order of the serum concentrations in the adults was IgG1 greater than IgG2 greater than IgA greater than IgM greater than IgG4 greater than IgG3. No correlation was found between the serum level and the IgSC number of individual isotypes (except for serum IgA and IgA1-SC). This new methodology should facilitate investigating the current status of immunoglobulin synthesis and the Ig repertoire in adults and children, in health and in disease.

Adult

Clinical and immunologic responses to Haemophilus influenzae type b-tetanus toxoid conjugate vaccine in infants injected at 3, 5, 7, and 18 months of age.

The safety and immunogenicity of Haemophilus influenzae type b-tetanus toxoid conjugate vaccine (Hib-TT) were evaluated in 77 healthy infants receiving injections at 3, 5, 7, and 18 months of age. No serious local or systemic reactions were noted. After the first injection the geometric mean Hib antibody level rose to 0.55 micrograms/ml, and each subsequent injection elicited a statistically significant rise in the geometric mean. The percentage of vaccinees with Hib antibody levels greater than 0.15 micrograms/ml serum was 75.5% after the first, 97.4% after the second, and 100% after the third Hib-TT injection. This percentage fell to 90.9% at 18 months of age but rose again to 100% after the fourth injection. Control infants (n = 10) injected with diphtheria-tetanus toxoid-pertussis vaccine only had nondetectable levels after the second injection. Hib-TT elicited increases of Hib antibody in all isotypes: IgG greater than IgM greater than IgA. Among IgG subclasses the highest increases were of IgG1. All vaccinated subjects had greater than 0.01 U/ml of TT antibody (estimated protective level) throughout the study. We conclude that Hib-TT, injected at 3, 5, 7, and 18 months, is safe and induces protective levels of antibodies during the age of highest incidence of meningitis caused by Hib.

Antibodies, Bacterial

Serum immunoglobulin G subclasses in children infected with human immunodeficiency virus type 1.

We studied serum concentrations of IgG subclasses in 47 human immunodeficiency virus 1-infected (17 asymptomatic and 30 symptomatic) children. Thirty-nine of 47 (83%) had an abnormality of at least 1 subclass. Sixteen had only elevated IgG1, 6 had only elevated IgG3 and 12 had elevated IgG1 and IgG3 concentrations. IgG2, IgG4 and combined IgG2-IgG4 deficiency was found in 3, 4 and 4 patients, respectively. IgG2 concentrations did not differ between patients with (n = 23) or without (n = 24) bacterial infections. Additionally the number of bacterial infections was similar between the patients with normal or low IgG2 and/or low IgG4. These data indicate that IgG subclass abnormalities are found in most children with human immunodeficiency virus 1 infection, but quantitative deficiencies of specific subclasses do not appear to explain the high frequency of bacterial infections occurring in these patients.

Acquired Immunodeficiency Syndrome

Transcutaneous determination of tissue dihematoporphyrin ether content. A device to optimize photodynamic therapy.

Photodynamic therapy involves the use of light of appropriate wavelength to excite a photosensitizer resulting in tissue destruction. The photosensitizer dihematoporphyrin ether is selectively retained in tumors allowing for tumor destruction while sparing normal structures. Accessibility of skin tumors makes them well suited for photodynamic therapy. Tissue and tumor dihematoporphyrin ether content is estimated based on the amount of dihematoporphyrin ether administered. In our study, skin dihematoporphyrin ether content was measured in guinea pigs transcutaneously by a hand-held fluorometer and compared with dihematoporphyrin ether determinations done on skin biopsy specimens. Fluorometry was performed on guinea pigs receiving 0, 2.5, 5, 10, and 25 mg/kg of dihematoporphyrin ether. Transcutaneous measurements of skin fluorescence increased with increasing dihematoporphyrin ether dose and correlated well with skin dihematoporphyrin ether content as determined by extracting dihematoporphyrin ether from skin samples. Transcutaneous fluorescent measurements of guinea pigs given 0 and 2.5, 2.5 and 5, 5 and 10, and 10 and 25 mg/kg of dihematoporphyrin ether differed in a statistically significant manner. Transcutaneous fluorometric determination of dihematoporphyrin ether content and extraction of dihematoporphyrin ether from skin samples were able to reflect differences in dihematoporphyrin ether dosing and presumably skin dihematoporphyrin ether content. However, transcutaneous fluorometry provides an instantaneous estimate of tissue dihematoporphyrin ether without the need for a tissue sample. This may provide a clinical tool to predict more accurately the optimal light dose necessary to maximize photodynamic therapy.

Animals

In vitro photodynamic treatment of normal and human papilloma virus-transfected keratinocytes with photofrin II and red light.

Photodynamic therapy involves the use of light of appropriate wavelength to excite a photosensitizer to result in tissue destruction. The photosensitizer dihematoporphyrin ether and red light were used to treat normal and human papilloma virus type 18-transfected keratinocytes in vitro. Although both cell lines were sensitive to treatment, normal keratinocytes retained more dihematoporphyrin ether and were more sensitive to photodynamic therapy than were transfected cells. In vitro data fail to show the selective retention of dihematoporphyrin ether reported elsewhere in the literature in papillomas and tumors. We did not find selective uptake or retention of dihematoporphyrin ether by human papilloma virus-transfected cells, despite previously published in vivo data to the contrary. Dihematoporphyrin ether retention and thus selective photosensitivity of papillomas in vivo is not caused by individual cellular differences in the processing of dihematoporphyrin ether. In addition, because in vitro results may not parallel in vivo results, both in vivo and in vitro models must be investigated in the study of phototherapeutic agents.

Antiviral Agents