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Biomedical subjects

P Nelson

Publications and source records attributed to P Nelson.

At least 109 records · Page 6Linked to original sources
PubMed1989

Bullous emphysema in monozygotic twins.

Monozygotic twins who developed bullous emphysema are described. This occurrence suggests that there is a genetic component that predisposes to the development of this disorder.

Adult↗
PubMed1989

Learning problems, anger, perceived control, and misbehavior.

Fifty-four students diagnosed as having learning disabilities (LD) and 73 students in regular education were administered the School Anger Inventory and the Perceived Control at School Scale. Teachers and parents rated student deportment and motivation. Predictably, those in the LD sample indicated higher school anger levels and were rated as exhibiting more negative behavior, less positive behavior, and lower motivation for on-task performance. The samples did not differ in their ratings of perceived control, which was moderate, and were given comparable positive teacher ratings for recall of relevant and interesting material. Significant correlations between school anger and behavior were found only in the LD sample, and there was no significant overall relationship between school anger, behavior, and perceived control within either sample. Overall, however, students who reported both a high level of anger and high perceived control were found to exhibit more negative behavior than those with high anger and low perceived control.

Adolescent↗
PubMed1989

Toward a procedure for minimizing and detecting false positive diagnoses of learning disability.

Assessment procedures that can significantly enhance motivation to perform are needed so that poor performance due to low or avoidance motivation is not misdiagnosed as indicating ability deficits or as symptomatic of learning disabilities (LD). In this connection, research is under way to investigate the degree to which a highly motivating computer game learning task can improve differential diagnoses of LD. Findings from the initial investigation indicate that a large proportion of students diagnosed as LD were able to learn effectively when pursuing such a task. The results illustrate the key role motivation plays in determining the validity of diagnostic assessment and demonstrate the potential value of similar tasks for use in differentiating, from among individuals diagnosed as LD, those who do not have impaired learning processes.

Adolescent↗
PubMed1989

Female gene expression in the seminal vesicle of mice after prenatal exposure to diethylstilbestrol.

Previous studies from our laboratory on the feminization of the male mouse reproductive tract after prenatal exposure to diethylstilbestrol (DES) showed that the mRNA for the major estrogen-inducible uterine secretory protein, lactoferrin (LF), was constitutively expressed in the seminal vesicle of male mice exposed prenatally to DES, but not in the seminal vesicle of control mice. After castration, treatment with 17 beta-estradiol (20 micrograms/kg.day) for 3 days induced the LF mRNA in the seminal vesicle of both control and prenatally DES-exposed mice; however, the levels in DES-treated tissues were approximately 6-fold higher than those in control tissue. This report describes the presence of LF in seminal vesicle tissues and secretions of prenatally DES-exposed mice, as determined by immunohistochemistry and Western blot analysis. Further, these data are correlated with immunolocalization of the estrogen receptor in the seminal vesicle tissue. We conclude that the seminal vesicle of prenatally DES-exposed male mice has acquired two key characteristics of female tissues, namely LF production/regulation and estrogen receptor localization/distribution similar to that in uterine tissues.

Animals↗
PubMed1989

Progesterone and estradiol modulate interleukin-1 beta messenger ribonucleic acid levels in cultured human peripheral monocytes.

The relationship between the endocrine system and immune monokines, such as interleukin-1 (IL-1), is of increasing interest. IL-1, a protein secreted by peripheral monocytes and tissue macrophages, mediates a wide variety of immune responses, and its production appears to be inversely related to the level of gonadal steroids. In this report, we have investigated the relationship between estradiol and progesterone concentrations and the level of IL-1 beta mRNA in cultured human peripheral monocytes and pelvic macrophages. Human peripheral monocytes, isolated during the luteal phase of the menstrual cycle, were activated with lipopolysaccharide (10 micrograms/mL). Cellular RNA was isolated and analyzed by Northern analysis using an 800-basepair IL-1 beta cDNA probe. Hybridization with 32P-labeled probe showed maximal levels of IL-1 beta mRNA occurring between 3 and 7 h of culture. Cultures of lipopolysaccharide-activated human peripheral monocytes incubated for 3-6 h with increasing amounts of progesterone or estradiol (0-10(-5) M) in the presence of either 5% fetal calf serum or 0.1% BSA demonstrated an inverse relationship between IL-1 beta mRNA levels and steroid concentration. In both cases, IL-1 beta mRNA levels decreased by 80-90% as the progesterone concentration increased to 10(-5) M and by 70-90% as the estradiol concentration increased similarly. A similar 80% decrease in IL-1 beta mRNA was observed with peritoneal macrophages incubated with increasing amounts of progesterone. This reciprocal relationship between IL-1 beta mRNA and gonadal steroids may have important ramifications in reproductive biology for both embryonic implantation and fetal survival as well as for clinically relevant changes in bone mass.

Adult↗
PubMed1989

Mutations of the ras protooncogenes in chronic myelogenous leukemia: a high frequency of ras mutations in bcr/abl rearrangement-negative chronic myelogenous leukemia.

Seventy cases of chronic myelogenous leukemia (CML) were analyzed for the presence of ras mutations using polymerase chain reaction (PCR), oligonucleotide hybridization, and direct PCR sequencing. All cases had preceding cytogenetic and bcr rearrangement studies. Aberrant ras genes were detected in none of 39 patients with Philadelphia (Ph) chromosome or bcr/abl rearrangement positive chronic-phase CML and in only 1 of 18 patients in blast crisis, suggesting that ras mutations have little or no role in initiation or progression of common CML. Seven of 13, or 54% of patients with bcr/abl rearrangement negative chronic phase CML (atypical CML) harbored mutations in ras, however. This high incidence of ras mutations, together with the absence of bcr/abl rearrangement, provides evidence that atypical CML is an entity that is molecularly distinct from common CML. Moreover, the clinical characteristics and the high frequency of ras mutations suggest that atypical CML may constitute a subset of the myelodysplastic syndrome and may be best classified as a variant of chronic myelomonocytic leukemia (CMML).

Base Sequence↗
PubMed1988

Hyperlipidemia in pediatric patients undergoing peritoneal dialysis.

We evaluated serial measurements of serum lipid levels in 68 patients aged 12.6 +/- 4.7 years undergoing treatment with continuous ambulatory peritoneal dialysis/continuous cycling peritoneal dialysis (CAPD/CCPD). Fasting mean levels of triglycerides (TG) and cholesterol (C) were elevated above the 95th percentile of published normal values by 102% and 19%, respectively, at the start of dialysis. Except for a short-term decrease in TG levels at 6 and 9 months, no significant change in mean lipid levels was observed during a follow-up period of 2 years. At initiation of dialysis, elevated TG and C levels were present in 90% and 69% of the patients, respectively. The prevalence of hyperlipidemia (HL) varied between 63% and 88% (TG) and 61% and 93% (C), respectively, during the follow-up period. TG and C levels were not correlated with caloric intake (evaluated in 17 patients), serum albumin levels, treatment modality (CAPD or CCPD), a history of the nephrotic syndrome, or previous treatment with hemodialysis or transplantation. However, a significant inverse correlation was observed between age and serum lipids at the initiation of dialysis treatment and after 1 year (TG: r = -0.40; C: r = -0.44). Our data indicate a high prevalence of HL but no significant change of serum lipid levels during 2 years of treatment with CAPD/CCPD.

Adolescent↗
PubMed1988

Day hospital as an alternative to inpatient care for cancer patients: a random assignment trial.

A stratified, random-assignment trial of 442 cancer patients was conducted to evaluate medical, psychosocial, and financial outcomes of day hospital treatment as an alternative to inpatient care for certain cancer patients. Eligible patients required: a 4- to 8-hour treatment plan, including chemotherapy and other long-term intravenous (i.v.) treatment; a stable cardiovascular status; mental competence; no skilled overnight nursing; and a helper to assist with home care. Patients were ineligible if standard outpatient treatment was possible. No statistically significant (p less than 0.05) differences were found between the Adult Day Hospital (ADH) and Inpatient care in medical or psychosocial outcomes over the 60-day study period. The major difference was in medical costs--approximately one-third lower for ADH patients (p less than 0.001) than for the Inpatient group. The study demonstrates that day hospital care of medical oncology patients is clinically equivalent to Inpatient care, causes no negative psychosocial effects, and costs less than Inpatient care. Findings support the trend toward dehospitalization of medical treatment.

Adult↗
PubMed1988

Anger, perceived control and school behavior among students with learning problems.

With regard to students with learning problems, findings indicate that the more severe the learning problem, the greater the tendency toward anger in response to conflicts at school. The relationship between learning problem severity and perceptions of control at school was not significant, but anger was negatively correlated to perceived control. None of the variables were significantly related to misbehavior. A stepwise regression analysis indicated perceived control as the most potent single variable accounting for the variance in anger scores. Overall, findings highlight implications for work focused on reactions to learning problems and factors associated with their cause and correction.

Adolescent↗
PubMed1987

Strains and micromotions of press-fit femoral stem prostheses.

Average femoral geometry was determined from sections of 25 human femurs. A 'stem design program' was used to determine the largest femoral stem that could be introduced into the canal. The stem was fine tuned by observations of fit in Plexiglass models of the 25 femurs. This stem was called the 'Exact-Fit'. Type 1 stem was formed by grinding the anterior and posterior faces flat. Type 2 stem was formed by additionally grinding the medial and lateral faces flat. Four fresh femurs were used for the experiments. Strain gages were located on the proximal medial area and level with the distal lateral tip. Displacement transducers were mounted proximally to measure stem-bone micromotion. Vertical and anterior-posterior forces were applied to the femoral head and normal strain data obtained. The stems were then inserted in sequence and the strains and micromotions were measured. After the uncemented stems had been tested, a smaller size of 'exact-fit' stem was cemented and the tests repeated. The strains with the uncemented stems were closer to normal than with the cemented stems. For example, compressive calcar strains averaged 56% of normal uncemented compared with 30% cemented for the different loadings. The micromotion was higher uncemented, but was still at a low level. The 'exact-fit' stem gave less resultant micromotion than the type 1 and type 2 stems. The high variation of the strain results was attributed to variations in stem-bone contact and fit. The study provided information of direct application to press-fit stems in hip replacement surgery.

Bone Cements↗
PubMed1986

Raman spectroscopy of oxidized and reduced nicotinamide adenine dinucleotides.

We have measured the Raman spectra of oxidized nicotinamide adenine dinucleotide, NAD+, and its reduced form, NADH, as well as a series of fragments and analogues of NAD+ and NADH. In addition, we have studied the effects of pH as well as deuteration of the exchangeable protons on the Raman spectra of these molecules. In comparing the positions and intensities of the peaks in the fragment and analogue spectra with those of NADH and NAD+, we find that it is useful to consider these large molecules as consisting of component parts, namely, adenine, two ribose groups, two phosphate groups, and nicotinamide, for the purpose of assigning their spectral features. The Raman bands of NADH and NAD+ are found generally to arise from molecular motions in one or another of these molecular moieties, although some peaks are not quite so easily identified in this way. This type of assignment is the first step in a detailed understanding of the Raman spectra of NAD+ and NADH. This is needed to understand the binding properties of NADH and NAD+ acting as coenzymes with the NAD-linked dehydrogenases as deduced recently by using Raman spectroscopy.

Molecular Conformation↗
PubMed1986

Effects of oral calcium carbonate on control of serum phosphorus and changes in plasma aluminum levels after discontinuation of aluminum-containing gels in children receiving dialysis.

Orally administered calcium carbonate was evaluated as a phosphate binding agent in 15 children, ages 0.6 to 17.2 years, receiving maintenance dialysis. Changes in plasma aluminum concentration were assessed after discontinuation of treatment with aluminum-containing gels. The mean daily dose of calcium carbonate was 5.1 +/- 2.5 gm (384 +/- 315 mg/kg/day), and correlated inversely with body weight (r = 0.72, P less than 0.01) and age (r = 0.71, P less than 0.01). Mean serum calcium, phosphorus, and bicarbonate values were unchanged throughout the study. Plasma aluminum concentration fell from 90 +/- 51 to 34 +/- 22 micrograms/L (P less than 0.005). Dietary phosphorus intakes were 44 +/- 21 and 42 +/- 19 mg/kg/day during the control period and at the end of the study, respectively. Transitory hypercalcemia was the only side effect in 92% of the patients. In none of the patients did uncontrolled hyperphosphatemia, metabolic alkalosis, diarrhea, or symptoms or signs of hypercalcemia develop. Our data indicate that calcium carbonate is an effective phosphate binding agent in children receiving dialysis, and should be used in lieu of aluminum-containing gels in young children with renal failure.

Adolescent↗