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Biomedical subjects

J H Carter

Publications and source records attributed to J H Carter.

At least 19 recordsLinked to original sources
PubMed1992

Effect of long-term therapy on the pharmacodynamics of levodopa. Relation to on-off phenomenon.

To determine how the response to levodopa is altered by long-term therapy, we examined the dose response to 2-hour infusions of levodopa in three groups of parkinsonian patients: those who were previously untreated, those who exhibited stable responses, and those who exhibited fluctuating responses to levodopa therapy, using tapping speed as an index of bradykinesia. The baseline tapping speed was greater in the patients with stable responses than in the untreated patients, probably representing a "long-duration response" to levodopa therapy. A "short-duration response," indicated by an increase in tapping speed lasting hours, was observed in most patients in all groups. The onset of the short-duration effect was more rapid and the incremental increase in tapping speed was twice as large in the patients with fluctuating responses compared with the untreated patients and patients with stable responses. The duration of the short-duration effect was greatest in the untreated group but did not differ between the groups with stable and fluctuating responses. Dyskinesia was not observed in any of the de novo patients but was observed in three of 12 patients with stable responses and eight of nine patients with fluctuating responses to levodopa therapy. Dyskinesia appeared before or with the antiparkinsonian effects in patients with stable responses, giving no indication of a higher threshold for dyskinesia in these patients compared with those with fluctuating responses. The plasma half-life clearance, volume of distribution, and maximum plasma concentrations of levodopa did not differ among groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Quantitative image cytometry of hepatocytes expressing gamma-glutamyl transpeptidase and glutathione S-transferase in diethylnitrosamine-initiated rats treated with phenobarbital and/or phthalate esters.

Image cytometry was used to quantify the volume of liver expressing two histochemical markers associated with neoplasia, gamma-glutamyl transpeptidase (GGT) and the placental isozyme of glutathione S-transferase (GST-P). Rats were treated with diethylnitrosamine (DENA) followed by phenobarbital (PB), di(2-ethylhexyl)phthalate (DEHP), or di-n-octyl-phthalate (DOP) for 26 weeks. In one series, PB-treated rats were given 2.0%, 0.5%, or 0.1% DEHP in the feed. GGT expression was detected diffusely throughout the liver parenchyma in several treatment groups so that any enhanced expression in altered foci (AF) and nodules (N) was not apparent. GST-P was detected only in AF and N. GST-P may represent a second genetic alteration, as GST-P+ AF and N also expressed GGT but not the reverse. The peroxisome proliferator DEHP inhibited expression of GGT or GST-P in livers of either DENA-treated or DENA+PB-treated rats. With GST-P the reduction was correlated to a reduced number of AF and N. In contrast, DEHP's stereoisomer, DOP, was as effective as PB in promoting expression of both markers. We conclude that image cytometry of hepatocytes expressing GST-P can be used in the bioassay of the carcinogenic potential of chemicals that affect liver proliferation.

Animals↗
PubMed1992

The effect of exercise on levodopa absorption.

We studied the effect of exercise using cycle ergometry on levodopa absorption in ten patients with Parkinson's disease. Oral levodopa was administered during exercise and at rest on separate days. Exercise delayed levodopa absorption in five patients, increased it in three, and did not influence it in two. We conclude that exercise can either increase or decrease levodopa absorption.

Absorption↗
PubMed1992

Black health professional families: assessment of strengths and stability.

Despite pernicious racism, most black health professionals achieve professional success and most have stable marriages. A 19-item questionnaire was designed to assess this hypothesis following a lecture on the strengths and weaknesses of black health professional families to physicians, dentists, and their spouses (n = 38) at the 1990 annual meeting of the combined Old North State Medical and Dental Societies of North Carolina. Surprisingly, these families seemed eager to disclose feelings about themselves, their professions, and their marriages. Major preliminary findings were that these health professionals were more prone to indicate unhappiness than their spouses and less likely to see racism as an impediment to careers, and more willing to acknowledge that they would like to correct something in their lives.

Black or African American↗
PubMed1991

Tics through Tourette's syndrome.

The concept of Tourette's syndrome as a bizarre and disabling disorder has changed with greater appreciation that this is a spectrum of symptoms and degrees of severity. A thorough understanding of the latest concepts regarding recognition and management is essential for the neuroscience nurse to play a meaningful role as counselor, educator and clinician in the care of these patients and families.

Antipsychotic Agents↗
PubMed1991

Chronic mental illness and homelessness in black populations: prologue and prospects.

Psychiatry has shown little regard for the special health concerns of African Americans, who are disproportionately represented among America's homeless. Although psychiatric literature is replete with data on homeless mentally disordered citizens, only incidental references are made to African Americans to satisfy federally funded research guidelines mandating the inclusion of racial minorities. Additionally, psychiatry has hesitated to suggest corrective actions for this national scourge and has begun to raise questions about the efficacy of case management and demonstration projects.

Black or African American↗
PubMed1990

Mutual support and mobilization preparedness: the method of an Army Reserve hospital.

Military literature fails to describe a successful methodology for developing and implementing active Army/active Army Reserve mutual medical support and mobilization planning. The author presents a method for addressing these critical issues that evolved over a period of 11 years between the 3274th Army Hospital (1000B), a Reserve unit in Durham, North Carolina and its CAPSTONE, Womack MEDDAC, Ft. Bragg, North Carolina. The principles utilized here are believed to be applicable to similar Table of Organization & Equipment Armed Forces Reserve Medical Units. Additional advantages of the method are that it enhances recruitment and retention, and maximizes the medical skills of Reserve medical personnel.

Cost-Benefit Analysis↗
PubMed1989

Influence of fluctuations of plasma large neutral amino acids with normal diets on the clinical response to levodopa.

Plasma large neutral amino acids (LNAAs) compete with levodopa for entry into the brain. Fluctuations in plasma LNAA concentrations could therefore contribute to variability in clinical response to levodopa. The hourly plasma levodopa, plasma LNAAs and clinical response were investigated in 11 fluctuating Parkinsonian patients on a regular hospital diet. The fluctuations in plasma levodopa were 2 to 3 times greater than the fluctuations of plasma LNAAs. The correlation between clinical response and plasma levodopa was substantially improved in only one patient by considering plasma LNAAs and calculating relative levodopa flux into brain. Although plasma LNAAs significantly increased during the day, the patients' clinical status did not uniformly deteriorate and mean afternoon clinical scores correlated better with mean plasma levodopa and levodopa flux than with mean plasma LNAAs. Minimum effective concentrations of levodopa for clinical response did not correlate with 9 am LNAA concentrations. It is concluded that in most patients, the relatively small variation in plasma LNAAs in comparison with the large variations in plasma levodopa indicates that fluctuations in LNAA are not an important contributor to the fluctuating response to levodopa.

Adult↗
PubMed1989

Amount and distribution of dietary protein affects clinical response to levodopa in Parkinson's disease.

Reducing dietary protein improves the effectiveness of levodopa (LD) but the most effective distribution of a low-protein diet (0.8 g/kg) is unclear. We compared a 1.6 g/kg protein diet, a 0.8 g/kg diet with protein evenly distributed between meals, and a 0.8 g/kg diet with protein restricted to the evening meal in 5 parkinsonian patients with motor fluctuations. We monitored clinical response, plasma LD, and plasma large amino acids (LNAAs) hourly throughout the day. Mean "on" times were 51% (1.6 g/kg diet), 67% (0.8 g/kg evenly distributed), and 77% (0.8 g/kg restricted). Hourly averages of plasma LD did not differ between the diets. The mean plasma LNAAs were 732 nmol/ml (1.6 g/kg diet), 640 (0.8 g/kg distributed), and 542 (0.8 g/kg restricted), and the diurnal pattern reflected the distribution of protein intake. In conclusion, the amount and distribution of dietary protein affect clinical response to LD. These effects are not related to LD absorption but are explained by the variation in plasma LNAAs.

Aged↗
PubMed1989

Impaired black physicians: a methodology for detection and rehabilitation.

The author contends that the great majority of black physicians lead happy and productive lives. Regrettably, black physicians must not only cope with stress related to marriage, finances, parenting, and other daily problems, but they must also cope with institutional racism. Consequently, some black physicians become impaired. This article discusses issues related to the problem of impairment in black physicians and suggests a methodology for detection and rehabilitation. It is the author's belief that future intervention should be culturally compatible and that black physicians themselves must bolster the effort to prevent impairment. At an empirical level, the author brings together the sparse amount of epidemiological and cultural data related to the subject.

Black or African American↗
PubMed1988

Adrenal regulation of mammary tumorigenesis in female Sprague-Dawley rats: incidence, latency, and yield of mammary tumors.

Huggins and Morii (J. Exp. Med., 114: 741, 1961) reported that massive adrenal necrosis occurs in 79 and 100% of female Sprague-Dawley rats receiving 20 and 30 mg, respectively, of the mammary carcinogen 7,12-dimethylbenz(a)anthracene (DMBA). Here, adrenal necrosis and regeneration were studied in 158 rats for up to 21 days post-DMBA by radioautography of the adrenals of animals given 50 microCi [3H]thymidine 30 min before sacrifice. Adrenal cell proliferation was markedly inhibited 21 days post-DMBA. Regenerated adrenals were more susceptible to this adrenocorticolytic effect. To investigate if alterations in adrenal function modify tumorigenesis, animals underwent adrenalectomies (ADX), hypophysectomies, ovariectomies, and pituitary transplants alone or in combination 6 days after receiving DMBA (20 mg/100 g intragastrically) at 50 days of age. To prevent adrenal necrosis, 24 animals were pretreated with metyrapone. Methylprednisolone acetate, 1 mg i.m., was given to 40 animals every 5 days beginning 6 days post-DMBA. There were 50 non-DMBA-treated intact and surgical controls. DMBA was necessary but not sufficient to induce mammary tumors. No tumors developed in controls or in 46 animals hypophysectomized 6 days after DMBA. Metyrapone reduced tumor incidence and yield. ADX after DMBA treatment increased the tumorigenic response and eliminated resistance to tumorigenesis in older rats. Only three tumors developed in DMBA-treated rats receiving methylprednisolone acetate. Mammary tumorigenesis was increased by pituitary transplant 6 days after DMBA to intact and ADX animals. Ovariectomy 6 days after DMBA was as effective as methylprednisolone acetate in preventing tumorigenesis; ADX did not overcome either inhibition. We conclude that adrenal hormones inhibit proliferation of initiated mammary cells.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

Adrenal regulation of mammary tumorigenesis in female Sprague-Dawley rats: histopathology of mammary tumors.

Mammary tumors induced in female Sprague-Dawley rats by feeding 7,12-dimethylbenz(a)anthracene (DMBA; 20 mg/100 g body weight) were classified according to histological criteria of tissue differentiation, cellular atypia, and evidence of invasion. The 549 tumors could be placed in three categories, nodular hyperplasia, nodular hyperplasia with atypia, and carcinoma, and combinations of all three. Although tumors classified histologically as carcinomas did not metastasize, upon transplantation to the kidney capsule, a tumor classified as a carcinoma grew for eight generations and metastasized. Tumor heterogeneity was a common finding in DMBA-initiated tumors. Carcinomas were an early lesion. As the length of time between DMBA treatment and sacrifice increased, more tumors with areas of carcinoma were found. Therefore, DMBA-initiated tumors progressed to carcinomas either soon after initiation or later by development within nodular hyperplasias. In 4 separate groups of animals (74 adrenalectomized rats and 90 intact rats), postinitiation adrenalectomy increased the numbers of carcinomas compared to intact animals. This effect was consistently seen in the cervical and thoracic mammary glands. We propose that the mechanism for enhancement of progression to greater malignancy by adrenalectomy may be inhibition of differentiation of initiated cells in the absence of glucocorticoids.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

Quantitative and qualitative immunohistochemical detection of myc and src oncogene proteins in normal, nodule, and neoplastic rat liver.

This study examined the possibility of using an immunohistochemical technique to detect the expression of myc and src oncogene proteins (ops) in livers of male Sprague-Dawley rats after treatment with the carcinogen diethylnitrosamine (with or without phenobarbital promotion) or untreated. We found that the majority of nodules and tumors from these livers stained for myc and src ops, indicating that myc and src expression did occur in these structures. These results were expected, since myc and src expression has been previously observed by others using different techniques. However, in our study, myc and src op staining was also noted in normal liver areas from rats in any of the four treatment groups (DENA, DENA + PB, PB alone, or untreated). The staining pattern of normal liver was different for each oncogene probe but was consistent within the four groups. In most cases, oncogene expression of normal liver occurred at sites of abnormal (but non-neoplastic) hepatocytes. The method reported here used both a qualitative technique of op expression analysis and a quantitative method using a Zeiss computer-driven image analysis system.

Animals↗