Biomedical subjects

C H Brown

Publications and source records attributed to C H Brown.

At least 19 recordsLinked to original sources

PubMed1992

Frequency and intensity discrimination in Mongolian gerbils, African monkeys and humans.

Frequency (delta F) and intensity (delta I) difference limens were directly compared in Mongolian gerbils (Meriones unguiculatus), Old World African Monkeys (Cercopithecus mitis, Cercocebus albigena), and humans. Methods employed a repeating background AX discrimination procedure, and positive (food) reinforcement for animals. For delta I, there were small quantitative differences between the species. At 1 kHz, 70 dB SPL, DLs averaged 2.82 dB for gerbils, 2.29 dB for monkeys, and 0.75 dB for humans. For delta F, there were larger differences between the species. At 1 kHz, 60 dB SPL, frequency DLs were highest for gerbils, averaging 108 Hz. DLs were lower for monkeys, averaging 32.6 Hz, similar to recently reported DLs for other Old World monkeys (Prosen et al., 1990). Human DLs, averaging 2.27 Hz, were markedly lower than those of either monkeys or gerbils. These results suggest that animals provide better models of human delta I than delta F.

Acoustic Stimulation↗

PubMed1992

The epidemiology of psychiatrist-ascertained depression and DSM-III depressive disorders. Results from the Eastern Baltimore Mental Health Survey Clinical Reappraisal.

Psychiatrists used a semi-structured Standardized Psychiatric Examination method to examine 810 adults drawn from a probability sample of eastern Baltimore residents in 1981. Of the population, 5.9% was found to be significantly depressed. DSM-III major depression (MD) had a prevalence of 1.1% and 'non-major depression' (nMD), our collective term for the other depressive disorder categories in DSM-III, had a prevalence of 3.4%. The two types of depression differed by sex ratio, age-specific prevalence, symptom severity, symptom profiles, and family history of suicide. Analyses using a multiple logistic regression model discerned that both types of depression were influenced by adverse life events, and that nMD was influenced strongly by gender, marital status, and lack of employment outside the home. Neither type of depression was influenced by income, education, or race. This study validates the concept of major depression as a clinical entity. Future studies of the aetiology, mechanism, and treatment of depression should distinguish between these two types of depression.

Adult↗

PubMed1992

Risk factors in schizophrenia. Season of birth, gender, and familial risk.

The risk for schizophrenia among first-degree relatives of schizophrenic probands obtained from an epidemiological sample using family history methods was examined to determine whether month of birth of the proband was associated with familial risk. The results of this study of the first-degree relatives of 106 female schizophrenics and 275 male schizophrenics suggested that the relatives of probands born in the months February to May had the highest risk, although the association between month of birth and familial risk among the male probands was present only for those relatives who had onset of schizophrenia before the age of 30.

Adult↗

PubMed1992

The role of family factors, physical abuse, and sexual victimization experiences in high-risk youths' alcohol and other drug use and delinquency: a longitudinal model.

Our understanding of the adverse effects of early child physical and sexual abuse has developed to a point where there is need to elucidate the processes by which various developmental outcomes occur. Limited variability on key measures of family stress and in youths' drug use, other delinquent behavior and abuse histories in the general population has limited theory development. Using data from an ongoing, longitudinal study of juvenile detainees, we test a developmental damage model of the relationships among the youths' family background and problem factors, their sexual victimization and physical abuse experiences, and their substance use and delinquent behavior over time. The hypothesized model was supported by the data. Theoretical and policy implications of the results are drawn. In particular, early intervention with high-risk youths and their families is needed to address effectively their problems and troubled behavior before drug use and delinquent careers become firmly established.

Adolescent↗

PubMed1992

Predictors of functional outcomes after arthroscopic partial meniscectomy.

OBJECTIVE: To confirm previous studies that have identified knee osteoarthritis as the principal correlate of poor outcomes after arthroscopic partial meniscectomy (APM), we considered a range of other preoperative characteristics using multivariable analyses to control for confounding variables. METHODS: One hundred five patients who had APM were studied. Selected demographic and clinical features were obtained from charts and operative notes. Preoperative and current functional status were determined by patient interviews. The principal outcomes were functional status at the time of followup, measured by the Physical Activity Scale of the SF-36 Health Status Inventory, and the Lysholm Knee Rating Scale. RESULTS: SF-36 scores improved from a mean of 53.7 to a mean of 18.2. The percentage of patients with satisfactory (> or = 77) Lysholm scores increased from 5% preoperatively to 73%. In multivariable analyses, Worker's Compensation (p = 0.003), worse baseline physical functional status (p = 0.007), and Grade III-IV cartilage damage (p = 0.05) were associated with worse post-operative function. CONCLUSION: The outcome of APM is generally favorable. The extent of cartilage damage was confirmed as a correlate of poor outcome. However, Worker's Compensation and preoperative physical functional status had the greatest prognostic value and should be ascertained routinely in orthopedic outcome studies.

Adult↗

PubMed1991

Comparison of mediational selected strategies and sequential designs for preventive trials: comments on a proposal by Pillow et al.

Compared the strengths and weaknesses of a novel intervention design strategy called mediational selection, proposed by Pillow et al. (1991), with designs based on a sequence of trials, that is, those which build on prior work and at each stage are administered to subjects from subpopulations who have high risk or as yet poorly quantified risk. Both designs would be most useful in short-term preventive trials. The goals behind these two approaches, however, are quite different. Mediational selection strategies attempt to improve the chances that an intervention developed to modify theoretically important mediational factors will have significant impact by selecting a subject subpopulation that is expected to benefit the most. Sequential designs attempt to identify the extent to which an intervention succeeds or fails to work in subpopulations and allows for adjustment of the intervention to these subpopulations as necessary.

Child↗

PubMed1991

Developmental epidemiologically based preventive trials: baseline modeling of early target behaviors and depressive symptoms.

Describes a conceptual framework for identifying and targeting developmental antecedents in early childhood that have been shown in previous work to predict delinquency and violent behavior, heavy drug use, depression, and other psychiatric symptoms and possibly disorders in late adolescence and into adulthood. Criteria are described that guided choices of targets for two epidemiologically based, randomized preventive trials carried out in 19 elementary schools in the eastern half of Baltimore, involving more than 2,400 first-grade children over the course of first and second grades. Baseline models derived from the first of two cohorts show the evolving patterns of concurrence among the target antecedents. The central role of concentration problems emerged. From Fall to Spring in first grade, concentration problems led to shy and aggressive behavior and poor achievement in both genders and to depressive symptoms among girls. There was evidence for reciprocal relationships in girls. For example, depressive symptoms led to poor achievement in both girls and boys, whereas poor achievement led to depressive symptoms in girls but not boys, at least over the first-grade year. These results provide important epidemiological data relevant to the developmental paths leading to the problem outcomes and suggest preventive trials.

Adolescent↗

PubMed1991

Psychiatric morbidity in the relatives of patients with DSM-III schizophreniform disorder: comparisons with the relatives of schizophrenic and bipolar disorder patients.

Risks for psychiatric disorders (RDC) among first degree relatives of DSM-III schizophreniform, bipolar, and schizophrenic probands obtained from an epidemiologic sample using family history methods were examined. The relatives of the schizophreniform probands differed from the relatives of the schizophrenic and bipolar probands. The relatives of schizophreniform probands had significantly higher rates of affective illnesses (with the exception of bipolar illness) than the relatives of schizophrenic probands, and they had a significantly higher rate of psychotic affective disorders than the relatives of the bipolar probands.

Adolescent↗

PubMed1991

DSM-III compulsive personality disorder: an epidemiological survey.

A two-stage probability sample of community subjects was developed with a full psychiatric examination employing DSM-III criteria in conjunction with the Epidemiological Catchment Area (ECA) survey conducted in Baltimore, MD. This report details the observation on those subjects diagnosed with compulsive personality disorder and compulsive personality traits. The results indicate that this condition has a prevalence of 1.7% in a general population. Male, white, married and employed individuals receive this diagnosis most often. Our data suggest a dimensional rather than categorical character for this disorder. The disorder imparts a vulnerability for the development of anxiety disorders.

Adolescent↗

PubMed1991

The design of a panel study under an alternating Poisson process assumption.

We discuss the design of a panel study for the estimation of the average durations in the two states of an alternating Poisson process. Two types of designs are examined. The first fixes the number of follow-up waves but permits the total length of follow-up to vary, and the second varies the number of follow-up waves with fixed length. Simple expressions for nearly optimal designs are presented, and we compare these with designs allowing for continuous observation. Both equilibrium and nonequilibrium cases are examined. An example is given using morbidity data to illustrate how these results can be applied.

Follow-Up Studies↗

PubMed1991

Continuous infusion of interleukin-2 and cyclophosphamide as treatment of advanced cancers: a National Biotherapy Study Group Trial.

We have evaluated the effect of Interleukin-2 [IL-2] after Cyclophosphamide (C) chemotherapy in 41 patients with metastatic cancer. IL-2 was given as a continuous infusion priming cycle 36 hours after C at 1 gm/m2 intravenously. In 39 evaluable patients, there were no complete remissions [CR], 2 partial remissions [PR], and 1 had a minor response [MR]. Stable disease for 30 days was seen in 16 patients whereas 20 progressed. The durations of partial and minor responses were brief, ranging from 1-6 months. Grade 3-4 neutropenia was seen in 41%. This was more severe than seen with IL-2 alone or IL-2 combined with lower doses of C. The marrow suppression was due to the chemotherapy. This combination of IL-2 and C appears to be reasonably well tolerated by patients, but toxicity is greater and the response rate is no better than results achieved by IL-2 alone. Responses of 26 patients with renal cancer appear to be inferior to our historical data using IL-2/LAK cells without C. Immune monitoring demonstrated changes expected with C chemotherapy (i.e., a non-selective decline in immune function). C induced no further differences in IL-2 induced changes in immune function.

Adult↗

PubMed1991

Maternal employment during the early postpartum period: effects on initiation and continuation of breast-feeding.

This study sought to determine whether and to what extent maternal employment in the early post-partum period is associated with the initiation and continuation of breast-feeding in a heterogeneous, urban population. A panel of women were interviewed twice during the first 3 months postpartum. In analyses adjusted for maternal demographic characteristics, there was no association between planning to be employed within the first 6 months postpartum and initiation of breast-feeding. However, actually being employed was significantly associated with cessation of breast-feeding as early as 2 or 3 months postpartum, even after adjustment for maternal demographic variables. Less than one half of mothers who were employed were still breast-feeding at the second postpartum interview, whereas two thirds of those who were not employed were still breast-feeding. Among employed mothers, working no more than 20 hours per week appeared to be protective for continued breast-feeding.

Adult↗

PubMed1990

Age-incidence artifacts do not account for the season-of-birth effect in schizophrenia.

Contrary to the position taken by Lewis (1989), several articles have demonstrated an association between season of birth and the risk of schizophrenia after controlling for the age-incidence effect. The method used by Pulver et al. (1983) was misinterpreted by Lewis. Clarification of this method is provided along with additional references related to the season-of-birth issue.

Adult↗

PubMed1990

Schizophrenia: age at onset, gender and familial risk.

In a family history study of 366 schizophrenic probands and their 1851 first-degree relatives, we found a relationship between age at onset of psychosis in the male probands and the risk for schizophrenia in their relatives. The relatives of male schizophrenic probands whose onset of psychosis occurred when they were younger than 17 years of age had an increased risk of schizophrenia when compared with the relatives of male probands with an age at onset greater than 17. We did not find an association between age at onset of psychosis in the female probands and familial risk. Cox proportional hazards models permitted us to examine the relationship between age at onset of psychosis in the probands and familial risk while controlling for possible confounding effects.

Adolescent↗

PubMed1990

Protecting against nonrandomly missing data in longitudinal studies.

Nonrandomly missing data can pose serious problems in longitudinal studies. We generally have little knowledge about how missingness is related to the data values, and longitudinal studies are often far from complete. Two approaches that have been used to handle missing data--use of maximum likelihood with an ignorable mechanism and direct modeling of the missing data mechanism--have the disadvantage of not giving consistent estimates under important classes of nonrandom mechanisms. We introduce two protective estimators, that is, estimators that retain their consistency over a wide range of nonrandom mechanisms. We compare these protective estimators using longitudinal data from a mental health panel study. We also investigate their robustness to certain departures from normality.

Data Interpretation, Statistical↗

PubMed1989

Effects of different opiates on hypothalamic monoamine turnover and on plasma LH levels in pro-oestrous rats.

Opiate inhibition of luteinizing hormone (LH) appears to involve changes in hypothalamic monoaminergic activity. Agonists of mu-, kappa- and sigma-opioid receptors and an opiate antagonist were administered at the onset of the preovulatory LH surge and their effects on hypothalamic monoamine turnover, and on plasma LH levels, investigated. The opiate antagonist, naloxone, significantly increased both noradrenaline (NA) turnover and plasma LH levels. Morphine (mu-agonist), significantly decreased NA concentration and plasma LH levels, but significantly increased dopamine (DA) and serotonin (5-HT) activity. Levorphanol (another mu-agonist) significantly decreased both NA and 5-HT concentrations and had no effect on circulating LH. Cyclazocine, ketocyclazocine and tifluadom (kappa-agonists) increased NA turnover but only tifluadom increased 5-HT turnover, also reducing LH levels significantly. N-Allylnormetazocine (SKF 10,047; sigma-agonist) increased 5-HT activity but did not alter LH levels. This study has confirmed the existence of a heterogenous group of opioid receptors within the hypothalamus which modulate monoamine neurotransmitters controlling LH release.

Animals↗

PubMed1989

Producing still images in arthroscopy.

Videotape recordings of arthroscopic examinations and procedures provide excellent real-time records, but cannot take the place of still images for teaching, referrals, patient education, and publishing. New uses of still images may also emerge as techniques for obtaining them become more convenient and reliable. Current methods for obtaining still images include direct arthroscopic photography, video-screen photography, thermal video printers, and photographic video printers. Although direct arthroscopic photography provides the highest quality images, photographic video printers designed for arthroscopic use appear to provide the best balance of image quality, convenience, and versatility.

Arthroscopy↗

PubMed1988

Gastro-duodenal morbidity of para-aortic and iliac lymph node irradiation using a single anterior 16 MV X-ray field.

Eighty-one patients with testicular tumours received para-aortic and iliac lymph node irradiation using 16 MV X-rays through a single anterior field. Eleven of 62 patients with seminoma (18%) and 11 of 19 with teratoma (58%) developed dose-related gastro-duodenal complications. There were no long-term sequelae. The average follow-up is 4.3 years (range 9 months to 8 years). With this method of treatment the structures anterior to the nodes receive a higher dose than the nodes themselves, and it is not suitable when the patient's antero-posterior separation necessitates an applied dose greater than 4000 cGy in 20 daily fractions over 28 days (1351 RET).

Aorta↗