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Biomedical subjects

R Kenney

Publications and source records attributed to R Kenney.

10 recordsLinked to original sources
PubMed1999

Evidence that the high incidence of treatment failures in Indian kala-azar is due to the emergence of antimony-resistant strains of Leishmania donovani.

The possibility that the high frequency of treatment failures in Indian kala-azar might be due to infection with antimony-resistant strains of Leishmania donovani has not been experimentally addressed. L. donovani isolates were obtained from splenic aspiration smears of 24 patients in Bihar, India, who either did not respond (15) or did respond (9) to 1 or more full courses of treatment with sodium antimony gluconate (SAG). A strong correlation (P<.001) between clinical response and SAG sensitivity in vitro was observed only when strains were assayed as intracellular amastigotes: responsive isolates ED50=2.4+/-2.6, ED90=6.4+/-7.8 microgram SAG/mL; unresponsive isolates ED50=7.4+/-3.7 microgram SAG/mL, ED90=29.1+/-11.1 SAG/mL. No correlation with clinical response was found by use of extracellular promastigotes (ED50=48+/-22 vs. 52+/-29 microgram/mL). The emergence of antimony-resistant L. donovani strains appears to be a cause of treatment failures in India.

Adolescent↗
PubMed1999

Is the Internet useful for clinical practice?

BACKGROUND: Internet use in dentistry is increasing. The authors surveyed dentists to determine how they are using the Internet to support patient care and how useful they perceive the Internet to be. MATERIALS AND METHODS: The authors sent a 25-question survey to 455 subscribers to the Internet Dental Forum, an Internet discussion list. Participants completed the survey through a Web page or by e-mail during an 18-day period in December 1998. The survey included questions about when they began using the Internet and their motivations for doing so, their positive and negative experiences, where they use the Internet and why, their use of information resources--including electronic information resources--and demographics. RESULTS: The authors received 314 surveys from 438 participants, a 72 percent response rate. Participants reported demographic characteristics similar to national averages and were highly computer-literate. Most considered the Internet essential for their practice and had increased their Internet use for professional reasons over time. Ninety-seven percent of respondents used the Internet at home, and 68 percent used it in the office. Only 5 percent used the Internet in the treatment area. The primary reason cited by participants for using the Internet was to keep up in general, followed by to answer patient-specific questions and to provide patient education. Reduction of professional isolation was one of the most frequently cited advantages of using the Internet. CONCLUSIONS: The authors found that some dentists use the Internet to support clinical practice and that it helped dentists adopt new techniques for patient treatment and obtain information on new materials or products. CLINICAL IMPLICATIONS: The Internet appears to support clinical practice mostly indirectly, by helping users keep up in general, rather than by answering specific clinical questions.

Adult↗
PubMed1998

Photoelastic stress patterns produced by implant-retained overdentures.

STATEMENT OF PROBLEM: When 2 implants are used to support a removable overdenture, optimal stress distribution to minimize forces to the implants is desired. PURPOSE: This study used photoelastic analysis to compare the stress patterns generated around implants with 2 retention mechanisms. MATERIAL AND METHODS: Two root form implants were anchored in a photoelastic mandible and a removable overdenture was fabricated. The denture was lined with a resilient layer of impression material to simulate oral mucosa. Attachment of the denture to the implants was varied by using ball/O-ring and bar-clip attachments. Vertical and oblique occlusal forces from 10 to 200 lb were applied unilaterally to the right and left first molars. Resultant stress distributions in the photoelastic mandible were photographed and evaluated. RESULTS: With vertical forces, the ball/O-ring attachment transferred minimal stress to both implants. Vertical forces applied to the bar-clip overdenture created immediate stress patterns of greater magnitude and concentration on both implants. A posterior oblique load resulted in similar stress patterns to both systems with slightly greater stress to the bar-clip overdenture. CONCLUSIONS: Within the limits of this study, ball/O-ring attachments transferred less stress to implants than the bar-clip attachments when the photoelastic model was subjected to a posterior vertical load.

Bite Force↗
PubMed1994

Typhlitis in a patient with acute lymphoblastic leukemia prior to the administration of chemotherapy.

PATIENTS AND METHODS: A 3-year-old girl with acute lymphoblastic leukemia developed typhlitis immediately after diagnosis and before the institution of chemotherapy. PURPOSE: Typhlitis is a necrotizing colitis that develops in immunodeficient patients with severe neutropenia. Most patients are leukemic children who are receiving or have received chemotherapy. Typhlitis in the absence of chemotherapy is rare. We report a fatal case of typhlitis in an untreated leukemic patient. RESULTS: This case emphasizes the multifactorial pathogenesis of typhlitis, which may occur in the absence of chemotherapy. CONCLUSIONS: Typhlitis should always be considered as a potential cause of acute sepsis and abdominal pain in a leukemic patient.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Carbohydrate utilization in exercising muscle in subtotally nephrectomized rabbits.

Subtotally nephrectomized rabbits were compared with sham-operated controls. The isolated soleus muscle of one leg was exercised using controlled stimulus parameters at 1 Hz until the contraction tension (amplitude) was reduced by one half. The muscle was then quickly frozen in liquid nitrogen and analyzed for lactate, pyruvate, glycogen, alanine, glutamine and alpha-ketoglutarate. The resting leg was used as a control and similarly frozen and analyzed. The difference between resting and exercised muscle lactate and pyruvate concentration was significantly greater in experimental animals while muscle alanine and alpha-ketoglutarate concentrations were lower in the experimental animals. There was no difference in the time required to reach one half of the muscle contraction amplitude between experimental and control animals. Blood lactate levels rose in the experimental animals to a greater degree than in control animals, similar to that seen in human subjects with renal failure.

Alanine↗
PubMed1978

The effect of concurrent manual activity on the dichotic listening performance of boys with learning disabilities.

Three groups of learning-disabled children, defined according to their Wechsler Intelligence Scale for Children (WISC) profiles, and one normal control group, were given both a standard dichotic listening task and a dichotic listening task performed concurrently with a manual tapping task. Learning-disabled children who showed no disparity in their verbal and performance subscale scores on the WISC demonstrated a right ear preference under standard testing and when tapping with the left hand, but not the right, which was nearly the same pattern as that obtained by the control group. Learning-disabled children whose verbal WISC score was at least 15 point lower than their performance demonstrated a right-ear preference only when tapping with their left hand. Finally, learning-disabled children who had high verbal, low performance WISC profiles showed no ear preference under any conditions. These results were interpreted as indicating that these three types of learning-disabled children are differentially lateralized and differentially affected by the facilitory-inhibitory effects of concurrent hemispheric activities.

Adolescent↗
PubMed1976

Maintainance of specificity, information, and thermostability in thermophilic Bacillus sp. glutamine synthetase.

Glutamine synthetase has been purified to homogeneity from B. subtilis (37 degrees) B. stearothermophilus (55 degrees), and B. caldolyticus (75 degrees). Those characteristics compared include size (6.0 +/- 0.3 X 10(5) daltons), quaternary structure (12 SU) amino acid content, substrate Km's and specificity for structural analogs, metal ion activation, number and kind of separate feedback modifier sites, and the complexity of modifier-substrate and modifier-modifier site interactions. Although the 37 degrees and 55 degrees systems are quite similar, the 75 degrees system shows important alterations in substrate specificity and modes of modifier action. Whereas at 37 degrees and 55 degrees AMP inhibits synergistically with amino acids (glycine, glutamine, histidine), the 75 degrees enzyme is inhibited directly by the products ADP, (which assumes the role of AMP) and glutamine, plus other ligands. Ligand binding domains are compared and found to be very different. Thermostabilization occurs by (a) protection by bound L-glutamate, (b) protein aggregation, (c) trends in the content of total polar residues, total Asx + Flx residues, the average hydrophobicity, and (d) disulfide bond cross-linking. Such studies provide insights to molecular evolution occurring with changes in environmental stress.

Adenine Nucleotides↗