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Biomedical subjects

R A Price

Publications and source records attributed to R A Price.

14 recordsLinked to original sources
PubMed1992

Extensive variation in evolutionary rate of rbcL gene sequences among seed plants.

Extensive variation in synonymous and nonsynonymous rates of substitution was observed among 50 sequences of the gene coding for the large subunit of ribulose-1,5-bisphosphate carboxylase (rbcL) representing bryophyte, conifer, dicot, and monocot taxa. Relative rate tests revealed rate differences of up to 138% for nonsynonymous substitutions and up to 85% for synonymous ones. Within angiosperms, the annual forms evolved more rapidly, on average, than perennial forms. This rate heterogeneity was more extensive at nonsynonymous sites than synonymous ones, and it resulted primarily from a recent acceleration of substitution rate in many groups of angiosperms.

Biological Evolution↗
PubMed1992

Obesity in Pima Indians. Distribution characteristics and possible thresholds for genetic studies.

We examined distribution characteristics of the body mass index (BMI; weight/height; kg/m2) in a sample of 1128 male and 1372 female Pima Indians aged 15-65 years. We found that women had a higher mean and variance of BMI than men. From commingling analyses, we determined that the distribution of BMI could be accounted for either by a single skewed distribution or by a mixture of multiple normal components. These component distributions may be used to define provisional thresholds in selecting families for genetic studies. To ensure genetic segregation of obesity predisposing genes in Pima families will require that some members have BMIs > or = 40 kg/m2.

Adolescent↗
PubMed1991

Inheritance of human plasma dopamine-beta-hydroxylase thermal stability.

Although the structural gene for human dopamine-beta-hydroxylase (DBH) has been cloned, the mechanism by which DBH physical properties and activity are regulated is not well understood. Previous reports have suggested that three-allele or two-locus models may account for the genetic regulation of these traits in human blood. It is an interesting challenge to determine the extent to which quantitative analyses will complement or guide molecular genetic studies. In this study we analyzed data on the physical property of DBH thermal stability and DBH activity in 230 individuals in 53 families in an attempt to clarify genetic mechanisms for the inheritance of these traits. Commingling and segregation analyses of the thermal stability data provided the first clear evidence of a major gene polymorphism for DBH thermal stability analyzed as a quantitative trait. Major gene transmission was supported within a mixed model (chi 2[3] = 13.39, P less than .004). In keeping with earlier findings, similar analyses of DBH activity provided strong evidence of genetic transmission. However, in our data support for a major gene polymorphism was equivocal (chi 2(2) = 2.99, P = .22).

Adolescent↗
PubMed1991

Weight change in depression: influence of "disinhibition" is mediated by body mass and other variables.

The direction of weight change (gain or loss) in depression has recently been found to be a stable characteristic of patients across depressive episodes. A search for determinants of the direction of weight change revealed two candidates: the body mass index (BMI) (weight in kilograms/height in meters squared) and a psychological variable, "disinhibition" of dietary restraint. The present study, of 68 patients with a history of recurrent depression, found a significant correlation between BMI and weight change; in other words, heavier persons were more likely to gain weight if depressed. There was also a correlation between "disinhibition" and weight change. "Disinhibition" correlated with BMI and, when controlled for BMI, age and sex, the correlation between "disinhibition" and weight change fell to insignificance. We conclude that BMI along with age and sex mediated the correlation between "disinhibition" and weight change.

Appetite↗
PubMed1979

Histopathology of CNS leukemia and complications of therapy.

An understanding of the pathology of central nervous system (CNS) leukemia has evolved slowly. Observations in the 19th century clearly established CNS leukemia as a disease involving the leptomeninges. Although infiltration of the leptomeninges by leukemic cells remains the principal CNS lesion in patients with this disease, other histopathologic changes have become evident with the development of antileukemic therapy. During the early years of chemotherapy, as patient survival increased, the effects of chronic meningeal leukemia, e.g., increased intracranial pressure, became prominent. Only recently, following effective control of CNS leukemia with chemotherapy and irradiation, did it become clear that current methods of treatment can produce neurotoxic effects. Two specific examples are leukoencephalopathy and mineralizing microangiopathy, both apparently induced by the effects of radiation on the microvasculature. Only through careful prospective studies can the consequences and actual incidence of these two lesions be determined. These results will permit sounder judgments of whether the risks of CNS radiotherapy outweigh the known benefits.

Blood-Brain Barrier↗
PubMed1978

The central nervous system in childhood leukemia. III. Mineralizing microangiopathy and dystrophic calcification.

We determined the prevalence, histopathologic features, and clinical correlations of a distinctive vascular lesion within the central nervous system (CNS) of children who died with acute lymphoblastic leukemia (ALL). Of 163 brains examined at autopsy, 28 (17%) had a noninflammatory mineralizing microangiopathy, usually accompanied by varying amounts of necrosis and calcification in adjacent neural tissue. The lesion always involved the lenticular nucleus with or without additional involvement of cerebral cortex. It was not the cause of death in any patient. An analysis of clinical features common to patients with microangiopathy indicated that cranial irradiation, in doses as low as 1500 rad, had induced the degenerative process. Survival beyond 10 months from the time of irradiation and multiple postirradiation CNS leukemic relapses, both had significant influences on the development of the lesion. Chemotherapy, particularly systemic or intrathecal methotrexate, might have contributed to the disease process, but apparently was not the instigating factor. Patients at greatest risk for developing microangiopathy are those under 10 years of age at the time of cranial irradiation, who then live more than 10 months and develop multiple CNS leukemic relapses.

Adolescent↗
PubMed1977

Recurrent malignant melanoma: effect of adjuvant immunotherapy on survival.

Twenty-nine patients referred consecutively to a cancer clinic because of recurrent metastatic malignant melanoma were given 5 mg of Connaught Laboratories bacillus Calmette-Guérin (BCG) by multiple cutaneous puncture at weekly and later at monthly intervals. Eight were also treated with autologous tumour vaccine and three with intralesional BCG. This group was compared with a retrospective control group of 54 patients treated with surgery and radiotherapy alone after recurrence. Prognostic features such as site of primary and of first metastasis, disease-free interval, age and sex were similar in the two groups. However, the median survival from the time of first recurrence was 12 months in the control group but 21 months in the BCG-treated group. The major improvement was in patients with disease limited to the regional lymph nodes: the median survival was 16 months in the control group but over 32 months in the BCG-treated group. Autologous tumour vaccine appeared to have no effect on survival. Serial testing of immunocompetence did not offer any prognostic advantage, although the results of some tests correleated well with extent of disease.

BCG Vaccine↗
PubMed1976

Signs, symptoms, and pathophysiology of Pneumocystis carinii pneumonitis.

In 80 patients with Pneumocystis pneumonitis, the intial signs and symptoms of infection were usually fever and cough, followed by tachypnea and coryza. Flaring of the nasal alae and cyanosis occurred later. Blood gas composition was markedly altered in its acid-base profile in most patients at admission. There was moderate to severe respiratory alkalosis and hypoxia. Clinical manifestations were correlated with the extent of histopathologic changes in the lung. (Deprivation of protein in the diet of rats provoked P. carinii infection.) P. carinii infection was found in children with kwashiorkor; evidence of protein-calorie malnutrition is closely associated with P. carinii pneumonitis in children wiht cancer and other primary diseases. P. carinii pneumonitis proved unique in that the causative organisms remained limited to the lungs even in fatal cases. No toxins have been identified, and systemic effects of the infection were only those that could be related to hypoxia and fever.

Adolescent↗
PubMed1975

The central nervous system in childhood leukemia. II. Subacute leukoencephalopathy.

A study was performed to evaluate the clinical and histopathologic characteristics of a distinctive degenerative lesion within the central nervous system (CNS) of children with acute lymphocytic leukemia (ALL). Of the 231 patients in this study, 13 were found to have specific degenerative changes in telencephalic white matter. Morphologically, the principal changes consisted of diffuse reactive astrocytosis and multiple, noninflammatory necrotic foci, often containing varying amount of mineralized cellular debris. Clinical features common to all patients with this leukoencephalopathy were: 1) cranial irradiation of 2000 rads or more and 2) methotrexate administered systemically after irradiation. Comparison of selected clinical features of patients with and without leukoencephalopathy showed that methotrexate administered intravenously after a cumulative dose of CNS irradiation of 2000 rads or more can result in degeneration of CNS white matter in patients with ALL. Age at time of irradiation, bacterial infections, nutrition, and CNS leukemia were not causally related to the development of this disease. This study suggests that chemotherapeutic agents may diffuse through the blood-brain barrier following CNS irradiation of 2000 rads or more.

Adolescent↗