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Biomedical subjects

J Powers

Publications and source records attributed to J Powers.

At least 55 records · Page 3Linked to original sources
PubMed1993

Reproducibility of urethral pressure profiles in clinically normal sexually intact female dogs by use of microtransducer catheters.

Urethral pressures profiles (UPP) obtained by use of microtransducer catheters were determined in 8 anestrous sexually intact female Beagles during general anesthesia. A UPP study consisted of 3 consecutive recordings, and 4 UPP studies were repeated at an interval of 5 days in each dog. Maximal urethral pressure (cm of H2O), bladder pressure (cm of H2O), and anatomic urethral length (cm) were recorded. Maximal urethral closure pressure (cm of H2O) was calculated. Mean +/- SD (for all measurements) maximal urethral closure pressure was 12.8 +/- 5.6 cm of H2O (range, 2.4 to 25.2 cm of H2O). Maximal urethral closure pressure was significantly (P < 0.05) decreased during the first recording period (11.4 +/- 5.8 cm of H2O), compared with the second (13.0 +/- 5.2 cm of H2O) or third (14.1 +/- 5.7 cm of H2O) recording periods within a UPP study (3 consecutive recordings). Mean maximal difference in urethral closure pressure during a single UPP study was 4.8 +/- 2.4 cm of H2O. Significant difference in maximal urethral closure pressure was not observed between studies. Mean (for all measurements) anatomic urethral length was 6.2 +/- 0.9 cm (4.1 to 7.8 cm). Anatomic urethral length was significantly (P < 0.05) less during the first recording period (6.1 +/- 0.9 cm), compared with values for the second and third periods (6.3 +/- 0.9 cm, 6.4 +/- 0.9 cm respectively). Anatomic urethral length for time 3 was significantly (P < 0.05) less than the value for time 1 (5.8 +/- 0.7 cm vs 6.6 +/- 0.8 cm).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Invasive aspergillosis of the central nervous system.

Advancing technology permits aggressive medical interventions that are often lifesaving, yet place the patient's immune system in temporary jeopardy. During the interval of immunocompromise, physicians must maintain vigilance for opportunistic infection by saprophytic organisms such as Aspergillus. Although the lung is the most common site of infection by this fungus, subsequent hematogenous dissemination with central nervous system involvement may occur. Currently, the majority of Aspergillus infections of the central nervous system remain unrecognized until the patient's demise. The clinical and pathological features of aspergillosis of the central nervous system are reviewed in order to promote earlier diagnosis and treatment.

Adult↗
PubMed1992

Patterns of accreditation performance in army family practice residencies.

Army leadership emphasizes training in all segments of its population, including family medicine. Standards for medical professional training, however, are provided by a civilian agency, the Accreditation Council for Graduate Medical Education (ACGME). In order to search for performance patterns, the authors reviewed the last two accreditation documents of each Army Family Practice residency. After independently scoring the documents against the written standards, the scores were compared with the actual written findings from the ACGME Residency Review Committee. The authors discuss patterns and trends resulting from this analysis, and recommend areas for future growth in the military training of family physicians.

Accreditation↗
PubMed1991

Lymphoma, motor neuron diseases, and amyotrophic lateral sclerosis.

We studied 9 patients with motor neuron disease and lymphoma. The following several observations have not been recognized in the past: (1) Motor neuron syndromes are associated with either Hodgkin's disease or non-Hodgkin's lymphoma. (2) The syndromes are not restricted to lower motor neuron disorders; 8 of 9 patients had definite or probable upper motor neuron signs as well, qualifying for the diagnosis of amyotrophic lateral sclerosis. Corticospinal tracts were affected in both postmortem examinations. (3) The combination of motor neuron disease and lymphoma is often accompanied by paraproteinemia (3 of 7 patients studied), increased cerebrospinal fluid protein content (6 of 9 patients), and cerebrospinal fluid oligoclonal bands (3 of 9 patients). (4) In 2 patients, asymptomatic non-Hodgkin's lymphoma was found only because the discovery of paraproteinemia gave impetus to examine the bone marrow. (5) Patients with both upper and lower motor neuron signs (amyotrophic lateral sclerosis) may show physiological evidence of conduction block in peripheral nerves or autopsy abnormalities in peripheral nerves. The cause of this syndrome is not known. Both lymphoma and motor neuron disease could have a common cause, possibly a retroviral infection. The frequency of paraproteinemia suggests that an immunological disorder may play a role in the pathogenesis of the neurological disorder.

Aged↗
PubMed1990

Statistical analysis of pharmacokinetic data with special applications to bioequivalence studies.

The objectives of this investigation are: 1) to describe techniques for determining the validity of the assumptions; 2) to suggest data transformations which may validate the use of parametric procedures; and 3) to describe a non-parametric alternative to the analysis of variance for crossover designs. Two assumptions common to all parametric procedures include the underlying normal distribution of the observations and equality of variances across treatment groups. Normal probability plots and/or stem and leaf plots are good diagnostic techniques to address the assumption of normality, while Bartlett's test is the most common method of determining equality of variances. To evaluate bioequivalence data, the Food and Drug Administration suggests the use of analysis of variance for crossover designs. If the underlying assumptions are valid, the appropriate statistical models are well known. On the other hand, if the assumptions are not valid, the investigator has one of two choices: 1) transform the data in such a way as to satisfy the assumptions, or 2) use a non-parametric procedure. Square root or logarithmic transformations are commonly used in this situation. However, if a suitable transformation cannot be found, then a non-parametric procedure should be used. Koch (Biometrics (1972) 28, 577-584) developed a non-parametric crossover test, which is relatively easy to apply, but the corresponding power calculations required by the FDA are less obvious.

Animals↗
PubMed1989

Effects on C3H mouse mammary cancer of changing from a high fat to a low fat diet before, at, or after puberty.

A low fat/low calorie (LF/LC) diet is a relative inhibitor of murine mammary cancer. Because the mammary gland may be most sensitive to the action of a carcinogen at or near the age of puberty, we studied whether beginning a LF/LC diet before puberty would decrease C3H/OuJ mouse mammary cancer incidence more than if such a diet was begun at or after puberty. We also studied whether the advancement of the age of puberty by a high fat/high calorie (HF/HC) diet would in itself be a mammary cancer risk factor and whether dietary fat levels would affect mammary cancer metastases. In the first study, mice were changed from a HF/HC diet to a LF/LC diet at 12 days of age, puberty, or 60 days of age. Other groups were always HF/HC or always LF/LC. In a second experiment, mice were fed a high fat diet for the same length of time, i.e., from 21 to 75 days of age (before and through puberty) or 75 to 129 days of age (well after puberty). In one aspect of the first study, puberty was advanced by feeding a HF/HC diet until the first day of puberty. However, tumor latency, incidence, and multiplicity were not statistically different from those of the LF/LC control. Other results of the first study indicated, in general, that mice consuming a LF/LC diet beginning at or before puberty had a longer tumor latency and a lower tumor incidence and multiplicity than mice either beginning a LF/LC diet at 60 days of age or continuously fed a HF/HC diet. Lung metatases were greater in mice fed a HF/HC diet continuously compared to LF/LC continuously. In the second study, beginning the high fat diet before or after puberty did not result in statistically significant differences in tumor latency, incidence, or multiplicity. It was concluded that the longer a LF/LC diet was fed, the lower was the mammary cancer risk. An early puberty in itself was not a mammary cancer risk factor and mouse puberty had no particular significance as an age before which a LF/LC diet should begin.

Animals↗
PubMed1989

A T cell epitope for experimental allergic neuritis is an amphipathic alpha-helical structure.

The bovine P2 protein is known to produce experimental allergic neuritis (EAN) in Lewis rats. The longest region of amphipathic alpha-helix within the bovine P2 protein was identified as residues 61-72. A synthetic peptide representing this sequence was synthesized and shown to have the ability to (1) produce EAN in Lewis rats by direct sensitization, (2) produce a lymphoproliferative response in a P2-specific T cell line, and (3) stimulate a P2 protein-specific T cell line sufficiently to transfer EAN to naive recipient Lewis rats. Residues 61-72 is the shortest sequence thus far identified that will produce EAN in the Lewis rat and supports the contention that T cell determinants tend to be amphipathic alpha-helices.

Amino Acid Sequence↗
PubMed1988

Human breast tumor imaging using 111In labeled monoclonal antibody: athymic mouse model.

The monoclonal antibody (MoAb) 323/A3, an IgG1, was raised against the human breast tumor cell line MCF-7 and recognized a 43 Kd membrane associated glycoprotein. Histochemical studies with the antibody detected 75% of metastatic lymph nodes, 59% of primary breast tumors, and showed some staining in 20% of benign breast lesions. For radionuclide imaging, the MoAb 323/A3 was labeled with both 125I and 111In, via covalently coupled diethylenetriaminepentaacetic acid (DTPA) by the mixed anhydride method. The antibody activity of the DTPA modified 323/A3 was assessed by an immunoassay using viable and fixed MCF-7 target cells. Male athymic nude mice bearing BT-20 human mammary tumors were injected with dual 125I/111In labeled DTPA 323/A3 via the tail veins. The animals were imaged with a gamma camera equipped with a pinhole collimator at 1-3 h, 1, 2, 3, 4 and 5 days after the tracer administration. On day 5 or 6, the animals were killed, and the biodistribution of the radiotracers was determined for the blood, thyroid, heart, lungs, liver, spleen, kidneys, gastrointestinal tract and tumor. Target to blood ratio at 6 days for the 111In tracer was 24:1 in the group with a mean tumor weight of 0.492 g, and 13:1 in another group with a mean tumor weight of 0.1906 g (day 5). However, the 125I activity showed only 3.6:1 and 5.4:1 target to blood ratios in the corresponding groups. The larger tumors localized less 111In tracer (27.13% +/- 7.57% injected dose/g, Mean +/- SD) than the smaller tumors (52.75% +/- 22.25% ID/g).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

The nature and substantiation of official sexual abuse reports.

A representative sample of 796 sexual abuse reports from New York State in 1985 was studied to explore factors associated with the decision to substantiate or unsubstantiate these reports. This study focused on the age, sex, and ethnicity of the subject child, and the source of the report as predictors of case substantiation. Substantiation rates tended to increase with the age of the child although this was more characteristic of reports involving female than male victims. Overall, reports involving female children were more likely to be substantiated than those involving male children. Ethnicity of the child showed no significant relationship to substantiation. Source of report, however, showed a strong relationship to case determination, with mandated reports found to be substantiated at a rate 13% higher than reports from non-mandated sources.

Child↗
PubMed1987

Carcinoid tumor of the biliary system. Case report and literature review.

Work-up of a 62-year-old black male, with a complaint of low back pain for three months, revealed a mass in the porta hepatis, narrowing of the common hepatic duct, and dilated intrahepatic bile ducts. A 3 X 4-cm tumor in the common hepatic duct was excised and biliary continuity restored by hepaticojejunostomy. The excised mass was a carcinoid tumor with no evidence of secretory activity. The patient is well 24.5 months after treatment. The literature on carcinoid tumors of the biliary tract is reviewed.

Bile Duct Neoplasms↗
PubMed1986

Proteins and RNA in mouse L cell core nucleoli and nucleolar matrix.

When intact nucleoli were prepared in the presence of enough leupeptin and phenylmethanesulfonyl fluoride to inhibit protease action, electrophoretic patterns of their constituent proteins were reproducible and very similar for L, HeLa, CHO, and rat hepatoma cells. "Core nucleoli", defined as that nucleolar fraction which remains after extensive DNase I action, had a protein composition similar to that of crude intact nucleoli, but were enriched for snRNA U3. Core nucleolar proteins included all of the histones, ribosomal proteins, and phosphorylated proteins with mobilities corresponding to 110 (protein C23) and 160 kilodaltons (kDa). The presence of protein C23 and of lamins A and C in nucleoli and core nucleoli was further verified by reaction with specific antibodies after one- or two-dimensional electrophoresis. A class of higher molecular weight proteins, ranging from 70 to greater than 200 kDa by mobility, was observed. It included at least 25 specific proteins, almost all of them highly acidic (pI less than 3.5). Treatment of core nucleoli with ethylenediaminetetraacetic acid/hypotonic buffer solubilized 30-35% of the small and large molecular weight proteins. In contrast, washing core nucleoli with 2 M NaCl selectively released U3 snRNA, 95% of the ribosomal RNA, and about half of the proteins, including C23 and most of the histones, ribosomal proteins, and other lower molecular weight proteins. The fraction remaining insoluble, "nucleolar matrix", was enriched for proteins of 34 and 57 kDa, lamins A and C, and most higher molecular weight proteins, as well as a portion of ribosomal spacer DNA.

Animals↗
PubMed1985

How not to select a computer system.

Deciding whether you should computerize the laboratory is a decision of the past. Today the question is which system to select. Here is a simple, practical approach to choosing a computer system.

Computers↗