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Biomedical subjects

L Kaplan

Publications and source records attributed to L Kaplan.

At least 145 records · Page 8Linked to original sources
PubMed1975

Revascularization after 3 hours of coronary arterial occlusion: effects on regional cardiac metabolic function and infarct size.

Two experimental series of closed chest dogs were compared: Group A (five dogs with 7 days of continuous occlusion of the proximal left anterior descending coronary artery); and Group B (six dogs with 7 days of reperfusion after 3 hours of acute occlusion of the same artery). Hemodynamic measurements, ventricular wall motion, coronary sinus blood flow and regional metabolism in both coronary occluded and nonoccluded segments of the left ventricle were measured sequentially. The infarct size was characterized by detailed histopathologic analysis. In the control dogs (Group A), mechanical and metabolic function remained severely depressed after 7 days of occlusion, and mean infarct size was 31.6 percent. In Group B, significant mechanical and metabolic dysfunction developed during 3 hours of occlusion and did not improve during the 1st hour of reperfusion. However, after 7 days of reperfusion, function returned to near preocclusion level. Mean infarct size was 14.2 percent, but in two of the six dogs infarct size was 43 percent and 23 percent, respectively. The study confirmed the unstable character of the early phase of reperfusion, attributed to cell swelling, edema and hemorrhages that resulted in inadequate coronary reflow, arrhythmias and functional derangements. Prolonged reperfusion for 7 days reduced mean infarct size and improved cardiac function.

Animals↗
PubMed1975

Consequences of coronary arterial occlusion on remote myocardium: effects of occlusion and reperfusion.

Focal necrosis (microinfarcts) and regional lactate derangements were observed in closed chest dogs in the nonoccluded (remote) posterior segments of the left and right ventricles after acute occlusion of the proximal left anterior descending coronary artery. Focal infarcts in the remote areas were observed in five of the six dogs with 7 days of occlusion of the left anterior descending artery and in six of seven dogs with 7 days of reperfusion after 3 hours of occlusion. There was a good correlation between the finding of microinfarcts and myocardial lactate derangements in the corresponding remote myocardium. No significant lactate derangements or microinfarcts were found in sham experiments. These findings suggest that ischemia of the remote myocardium frequently accompanies an acute coronary occlusion and may result in irreversible focal lesions.

Animals↗
PubMed1975

A new virus specified determinant of hepatitis B surface antigen.

One hundred and three samples from hepatitis B surface antigen (HB(s)Ag) positive Californian blood donors were subtyped in immunodiffusion with respect to d/y, w/r and a21, a23, a3. Spur formation with a human antiserum indicated a previously unrecognized determinant q, which was detected in 96 sera (4 a21yw, 15 a23yw, 69 a21dw and 8 adr). Out of 8 sera which by spur formation were demonstrated to lack q, 7 were further subtyped (2 a21dw and 5 a3dw). Hence all 5 a3 dw specimens were demonstrated to lack q, thus indicating that q is specified by the virus. The possible relation of q to x with further implications for the specification of x is discussed.

Antibodies, Viral↗
PubMed1973

Betaine-homocysteine transmethylase in Pseudomonas denitrificans, a vitamin B 12 overproducer.

A pantothenate-methionine auxotroph (J741) of Pseudomonas denitrificans was isolated whose growth requirement for methionine could not be satisfied by known precursors of the amino acid, including homocysteine. However, some "methyl rich" compounds such as betaine and dimethylacetothetin (DMT) could satisfy the requirement. S-Methyl-methionine and S-adenosylmethionine were ineffective. Extracts were found to contain an enzyme, betaine-homocysteine transmethylase (BHTase), that uses betaine or DMT as a methyl donor and homocysteine as an acceptor to produce methionine. Growth of J741 in methionine leads to a total repression of the BHTase, whereas the use of DMT leads to a three- to sixfold stimulation of enzyme synthesis compared to betaine-grown cells. The pantothenate requirement is unrelated to the methionine auxotrophy, since the growth of other single auxotrophic mutants as well as revertants of J741 still have their methionine requirement satisfied by betaine or DMT. Another methionine auxotroph that could not use betaine for growth was devoid of BHTase activity.

Betaine↗