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J M Whelan

Publications and source records attributed to J M Whelan.

5 recordsLinked to original sources
PubMed1992

Videoarthroscopy: review and state of the art.

Since the introduction of videoarthroscopy, there has been rapid technological advancement. The charged couple device (CCD) has become the standard small pickup unit for the present cameras. The video signal processing and transfer has been modified and improved. New Y/C or super VHS and red, green, blue (RGB) systems have been associated with improvements in monitors, video recorders, and video printers. Measurements of video quality such as resolution, signal-to-noise ratio, pixels, and contrast have been confusing to clinicians evaluating these new systems. Equipment compatibility and the weak-link theory is important to understand when selecting new equipment. This review article presents an update for the clinician who wants more information to differentiate among the new video arthroscopic systems.

Arthroscopy↗
PubMed1990

Discoid meniscus.

The discoid meniscus is probably a congenital deviation that usually occurs laterally. The Watanabe classification consists of complete, incomplete, or Wrisburg ligament types. Complete and incomplete discoid menisci normally require treatment only when a tear occurs. The Wrisburg ligament type lacks a posterior capsular attachment. The preferred treatment is repair of the posterior capsular disruption with saucerization of the remaining meniscus.

Adolescent↗
PubMed1987

Phase I study of TCNU, a novel nitrosourea.

TCNU is a chloroethyl nitrosourea based on the endogenous amino acid taurine. This paper reports its first evaluation in man. Eighty-four patients with refractory cancer received 12 dose escalations from 10-150 mg/m2 TCNU administered orally every 6 weeks. Clinical side-effects were predominantly gastro-intestinal but dose-limiting toxicity was thrombocytopenia. Pharmacokinetic monitoring with an HPLC assay sensitive to the nanogram range demonstrated unchanged TCNU in plasma for up to 8 h following administration. The mean half-life was 60 min. Clinical responses were seen in melanoma (four patients), lung cancer (two squamous, one small cell) and one patient each with renal and stomach cancer. These responses, together with the unusual pharmacokinetic profile of TCNU, warrant exploration in disease-orientated phase II studies at a recommended dose of 130 mg/m2 p.o. q 5 weeks.

Adolescent↗
PubMed1979

Factors affecting the rate of purine ribonucleotide dephosphorylation in human erythrocytes.

Purine ribonucleotide dephosphorylation was measured in intact human erythrocytes in vitro to evaluate those factors which might regulate this process in vivo. It was found that purine nucleotides which exist predominantly in the triphosphate form (e.g. ATP and GTP) are protected from dephosphorylation while those nucleotides normally present as the monophosphate (e.g. IMP) are susceptible to dephosphorylation. This point was emphasised by studying an individual whose erythrocytes accumulated ITP rather than IMP; erythrocytes from this individual has a more stable pool of inosine phosphates than did erythrocytes from normal individuals. The concentration of intracellular phosphate was also shown to affect the rate of dephosphorylation. The dephosphorylation of IMP was inhibited at intracellular phosphate concentrations above approx. 3 mM. AMP dephosphorylation (in cells whose AMP concentration was increased by incubating them in the presence of 2-deoxyglucose) was inhibited by phosphate more strongly than was found for IMP. In contrast, the dephosphorylation of GMP did not appear to be affected by phosphate concentration. High oxygen tension was a powerful stimulator of IMP dephosphorylation while low oxygen tension protected IMP from dephosphorylation. This finding shows that human erythrocytes are similar to those of other mammals in this regard and points to a possible physiological determinant of purine turnover in these cells.

Deoxyglucose↗