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Biomedical subjects

R Jones

Publications and source records attributed to R Jones.

At least 523 records · Page 29Linked to original sources
PubMed1994

The neurogenetics genie: testing for the Huntington's disease mutation.

Even though the discovery of the HD gene will make genetic testing much easier to perform, until there is an effective treatment, it will be no easier for HD families to learn who among them carries the mutation. We believe that the standard of care for obtaining genetic testing for HD, as well as for other inherited neurodegenerative disorders, must continue to include extensive counseling, psychological assessment and support, a neurologic examination, and post-test follow-up. We advocate a flexible approach consistent with the individual's particular needs, but we emphasize that it is essential that these basic elements be adequately addressed.

DNA Mutational Analysis↗
PubMed1994

A laboratory validation study of a portable system for remote recording of sleep-related respiratory disorders.

This study represents the validation of an out-of-laboratory recording system for screening sleep disorders by comparing it to an in-laboratory system which accomplishes complete polysomnography. Forty patient cases were collected. Each patient slept in the sleep laboratory with the simultaneous monitoring of eight channels from the Sleep I/T (CNS, Inc), as well as complete polysomnographic monitoring comparable to that which accomplishes routine patient evaluations utilizing the Sleeplab (CNS, Inc) system. The data collected on the Sleeplab system were analyzed in a computer-assisted manner followed by manual overreading of the raw data. The Sleep I/T data analysis was performed automatically using default parameters. The results revealed no significant differences in the determination of sleep efficiency, respiratory disturbance index (RDI), periodic leg movement (PLM) index, or the desaturation index. For the RDI, the sensitivity was 100 percent and the specificity was 93 percent for correctly detecting an RDI of 15 per hour, and the PLM index had a sensitivity of 89 percent and specificity of 97 percent in detecting episodes greater than 20 per hour. These data demonstrate excellent agreement between this out-of-laboratory system and polysomnography in its ability to detect accurately RDI, PLM index, and saturation levels.

Humans↗
PubMed1994

Some effects of zona pellucida glycoproteins and sulfated polymers on the autoactivation of boar sperm proacrosin and activity of beta-acrosin.

The effects of zona pellucida glycoproteins, sulfated polymers and non-sulfated polymers on the activation kinetics of boar sperm proacrosin to beta-acrosin have been investigated. The aim has been to understand more about the behaviour and function of this protein after it has been released from the acrosome at the time of fertilization. Purified proacrosin was allowed to autoactivate at pH 8.0 in the presence of different concentrations of homologous zona glycoproteins, sulfated polymers (fucoidan, chondroitin sulfates A, B and C, dextran sulfate, polyvinylsulfate and heparin) and non-sulfated polymers (dextran, polyvinylphosphate and hyaluronic acid). Enzyme activity was measured against N-benzoyl-L-arginine p-nitroanalide substrate and changes in molecular mass of the protein monitored by SDS-PAGE. Results show that zona pellucida glycoproteins, fucoidan, dextran sulfate and polyvinylsulfate all potentiate the conversion of proacrosin to beta-acrosin but subsequently inhibit its amidase activity. Dextran, polyvinylphosphate, chondroitin sulfates A, B and C and glucose-6-sulfate, on the other hand, either have no effect on autoactivation and beta-acrosin activity, or enhance it slightly. SDS-PAGE analysis confirmed these observations and further indicated that binding of sulfated polymers to proacrosin inhibited staining by Coomassie Blue. These results are consistent with the hypothesis that binding of zona pellucida glycoproteins and sulfated compounds to proacrosin/acrosin is stereospecific and that contact activation onto soluble 'surfaces' causes conformational changes that are responsible for potentiation or inhibition of activation. The implications of these findings for sperm binding and penetration of the zona pellucida are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrosin↗
PubMed1994

The role of vein patch in distal anastomotic intimal hyperplasia: an histologic characterization.

Comparison of the cumulative patency of four types of Polytetrafluoroethylene (PTFE) grafts with and without a vein patch at the distal anastomosis in one hundred and twenty ilio-femoral by-passes of sixty dogs revealed: (i) Vein patch improved patency in standard PTFE graft 10/16 (62.5%) versus without a vein patch 6/16 (27.5%) (p < 0.1). (ii) The less rigid thin wall PTFE graft did not benefit from vein patching 22/45 (48.8%) versus those without a vein patch 28/45 (62.2%) (p < 0.2). (iii) DAIH was present in all grafts with and without a vein patch and occurred exclusively at the heel and the toe of the graft plus the floor of the host artery three months after implantation. (iv) An organized fibrocellular multilamination characterized the cytoarchitecture of the DAIH. (v) A process of gradual cell transformation and orientation occurred in DAIH that spanned between the graft and the lumen. Vein patch at the distal anastomosis improved the patency of the more rigid standard PTFE grafts, and adversely affected the less rigid thin walled PTFE graft in dogs. The formation and distribution of DAIH was not altered by a vein patch at the distal anastomosis of PTFE grafts.

Anastomosis, Surgical↗
PubMed1994

Fractal analysis of pulmonary arteries: the fractal dimension is lower in pulmonary hypertension.

We analyzed the spatial structure of contact radiographs of barium-filled pulmonary arteries of rats raised in room air and in two environments that induce pulmonary arterial hypertension (PAH)--hypoxia and hyperoxia. We found that the spatial structure of the pulmonary arteries was fractal in both the control and the hypertensive lungs. The fractal dimension of the pulmonary arteries of the control lungs was 1.62 +/- 0.01 (mean +/- SEM), which is greater than that of both the hypoxic lungs 1.50 +/- 0.03 (p < 0.01) and the hyperoxic lungs 1.44 +/- 0.01 (p < 0.01). There was no significant difference between the hypoxic and hyperoxic lungs. The fractal dimension may be a useful clinical index to quantify pathologic changes in the pulmonary arterial tree.

Animals↗
PubMed1994

Measles vaccine failures: lack of sustained measles-specific immunoglobulin G responses in revaccinated adolescents and young adults.

The measles-specific antibody responses of seronegative adolescents and young adults were evaluated after revaccination. Of 1650 previously vaccinated healthy volunteers between the ages of 10 and 30 years, 4.4% were found to be seronegative for measles antibodies and 9.9% had equivocal titers. Seronegative volunteers were revaccinated to measles and followed serially for development of measles-specific IgG. Of 43 subjects followed for at least 1 year, only 58% developed and maintained positive antibody titers; 12% never developed positive titers and 30% initially developed titers that fell below positive levels within 1 year. The peak titers achieved by those subjects who responded transiently were lower than those achieved by subjects who developed sustained responses. Thus even after the recommended two dose schedule of the current measles vaccine, some adolescents and young adults lack protective titers of measles-specific antibody.

Adolescent↗
PubMed1994

Auditory stimulation effect on a comatose survivor of traumatic brain injury.

The purposes of this case study were (1) to determine whether a comatose patient responded differentially to four types of auditory stimuli--voices of family members and friends, classical music, popular music, and nature sounds--and (2) to determine what physiological measures and behavioral observations best captured changes in responsiveness. The patient participated in 28 sessions that were videotaped for later behavioral analysis. During all sessions, measures were taken of pulse rate, respiration rate, and skin resistance. Visual inspection of the data and Auto Regressive Integrated Moving Average (ARIMA) analyses revealed greater increases in responsiveness with the presentation of taped voices of family and friends than with other types of taped stimuli. Behavioral observations of body movements and measures of pulse rate were superior to observations of facial expressions and measures of respiration rate and galvanic skin response in revealing changes in responsiveness. Despite extreme diversity among comatose persons, the research findings support the contention that responses to various auditory stimuli differ and are measurable with relatively simple behavioral and physiological observations.

Acoustic Stimulation↗
PubMed1993

Randomized trial of high-dose chemotherapy with autologous bone marrow support as adjuvant therapy for high-risk, multi-node-positive malignant melanoma.

BACKGROUND: Chemotherapy adjuvant to surgery in metastatic melanoma has been evaluated in only a few prospective randomized trials. In the treatment of metastatic melanoma, dacarbazine has response rates of 15%-25% and in several studies, when combined with other alkylating agents, has yielded even higher response rates. Among the highest response rates are those achieved by using high-dose chemotherapy regimens combined with autologous bone marrow support (transplantation). PURPOSE: We conducted a prospective randomized clinical trial to test the efficacy of high-dose alkylating agents in combination with autologous bone marrow support given as adjuvant therapy for high-risk stage II (World Health Organization) melanoma. METHODS: Thirty-nine patients with metastases involving five or more lymph nodes were randomly assigned to one of two treatment arms within 8 weeks of lymphadenectomy: immediate treatment or observation only. The immediate-treatment arm consisted of 19 patients who, immediately after random assignment, received high-dose chemotherapy with alkylating agents, followed 3 days later by reinfusion of autologous bone marrow. The observation arm consisted of 20 patients who were observed until relapse (confirmed by biopsy) and were then treated with the identical high-dose alkylating agent chemotherapy followed by reinfusion of autologous bone marrow. Bone marrow was harvested from the patients under general anesthesia 1-2 weeks prior to chemotherapy and was cryopreserved. Chemotherapy consisted of intravenous administration of cyclophosphamide (1875 mg/m2 as a 1-hour infusion daily for 3 days), cisplatin (55 mg/m2 per day by continuous infusion over the same 72-hour period), and carmustine (BCNU) (600 mg/m2) given immediately after cisplatin on the 4th day as a 2-hour infusion. The total doses of the three drugs were 5625, 165, and 600 mg/m2, respectively. All patients received medical evaluations every 6-12 weeks over the study period. Kaplan-Meier estimates were used to determine the time to disease progression on the basis of intent to treat. RESULTS: There was no statistically significant difference in overall survival or in time to disease progression between the two treatment arms. However, the median time to progression was 16 weeks in the observation arm and 35 weeks in the immediate-treatment arm. CONCLUSIONS: Immediate adjuvant high-dose chemotherapy with alkylating agents followed by autologous bone marrow support more than doubled the time to disease progression compared with observation alone, though the difference was not statistically significant. No differences in overall survival were noted.

Adult↗