Coronary vasodilator reserve impairment distal to systolic coronary artery compression in dogs

To investigate the mechanism by which muscular coronary overbridging can cause myocardial ischaemia, we studied the effect of systolic compression (SC) of the proximal left circumflex coronary artery in ten anaesthetised dogs, with both intact autoregulation and maximally dilated coronary arteries. Systolic compression was produced by a mechanical device adjusted to interrupt circumflex coronary flow only during the aortic ejection period and we measured left ventricular, aortic and distal circumflex coronary pressures, phasic coronary blood flow, regional myocardial blood flow (RMBF), myocardial oxygen consumption (MVO2), and myocardial lactate extraction (MLE). During both autoregulation and maximal coronary vasodilatation, there was a diastolic time lag after SC to restart phasic circumflex coronary blood flow (34 +/- 3 vs 31 +/- 3 ms) and to increase distal circumflex coronary pressure (69 +/- 4 vs 79 +/- 6 ms). With autoregulation, SC reduced the diastolic circumflex coronary: systolic left ventricular pressure time ratio (DPTIc:SPTI) and there were no changes in the other measured variables. During maximal coronary vasodilatation and SC, the coronary vasodilator reserve, the DPTIc:SPTI ratio and the inner:outer myocardial blood flow distribution were decreased in the territory of the left circumflex coronary artery; a linear relationship was observed between the DPTIc:SPTI and the inner:outer myocardial blood flow ratio. Systolic compression during vasodilatation also produced a reduction in myocardial oxygen consumption of the whole heart and a production of lactate in the coronary sinus. These results suggest that myocardial ischaemia with a myocardial bridge is due to the combined effects of a diastolic time lag to repressurise the coronary vascular bed, of tachycardia and of coronary vasodilatation.

Increased plasma concentrations of prostacyclin metabolite 6-keto-PGF1 alpha in essential hypertension. Influence of therapy with labetalol

To evaluate the role of the vasoactive prostaglandins prostacyclin and thromboxane A2 in essential hypertension, the stable metabolites 6-keto-PGF1 alpha and thromboxane B2, respectively, were measured in plasma before and after therapy in 7 patients. During the placebo phase, plasma 6-keto-PGF1 alpha levels were significantly greater than normal. Plasma thromboxane B2 levels were not statistically different from those in normal subjects. After intravenous administration of labetalol to the point of blood pressure reduction, neither plasma 6-keto-PGF1 alpha nor thromboxane B2 values changed. With prolonged oral labetalol therapy and concurrent regulation of blood pressure, a significant decrease in plasma 6-keto-PGF1 alpha levels occurred while thromboxane B2 values remained unaltered. Elevation of plasma 6-keto-PGF1 alpha in untreated hypertensive subjects suggests that enhanced vessel wall prostacyclin synthesis may be a protective mechanism to prevent organ damage. As blood pressure is controlled this increase is no longer needed, and prostacyclin generation returns to normal.

Comparison of umbilical vein models for measurement of relative prostacyclin and thromboxane production

There is growing evidence that blood vessels generate TXA2 in addition to PGI2. We examined effluents from continuously perfused human umbilical vein and supernatants from umbilical vein rings for TXB2 and 6-keto-PGF1 alpha measurements (stable metabolites of TXA2 and PGI2, respectively). TXB2 and 6-keto-PGF1 alpha were identified in all samples. 6-keto-PGF1 alpha to TXB2 ratio was higher in intact vein effluents than in the venous ring supernatants (112:1 and 28:1, respectively, P less than 0.01). Arachidonate stimulation increased 6-keto-PGF1 alpha and TXB2 levels similarly in the intact vein effluent. In contrast, stimulation of the venous rings resulted in a relatively larger increase in TXB2 than in 6-keto-PGF1 alpha. This caused 6-keto-PGF1 alpha to TXB2 ratio to decline (p less than 0.01). The identity of TXB2 was confirmed in several different ways. These data suggest that 1) human umbilical veins produce TXA2 in addition to PGI2, 2) TXA2 release is more by venous rings than by the intact vein probably reflecting contribution from non-endothelial layers, and 3) arachidonate stimulation causes relatively greater release of TXA2 than of PGI2 from the venous rings, whereas release of PGI2 and TXA2 is similar from the intact vein.

[Blount's disease: a review of 8 cases (author's transl)]

The authors have reviewed eight cases of infantile tibia vara. All were treated operatively. Five patients were young children (less than 5 years old); they were treated by a single osteotomy into valgus and lateral rotation. Three children were older at the time of surgery. The deformity recurred in all of them and a second operation was required of elevation of the lateral tibial plateau and lateral epiplysiodesis. The authors emphasise the need for early correction of deformity to produce better mechanical function of the knee and balanced epiphyseal growth.

Untreated scoliosis in the adult

Untreated scoliosis affects the quality of life and is a disabling disease in the adult. Most patients can expect back pain, particularly after the age of 30, and one in 4 may be disabled by it. The majority of adults are embarassed by their deformity. Women, in particular, are less likely to marry. Surgical treatment of the adult is difficult and hazardous, and is associated with socioeconomic problems not encountered in the adolescent. Scoliosis should be treated definitively before the end of the period of growth.

Diagnosis of rubella virus infections. I. A comparison between Vero and BHK-21 cells for the detection of specific IgG and IgM antibodies by immunofluorescence

Vero cells were more suitable then BHK-21 cells for the detection of rubella-specific IgG antibodies because the nonspecific fluorescence was minimal. However, BHK-21 cells were found more sensitive than Vero cells for the detection of rubella-specific IgM antibodies.

Diagnosis of rubella virus infections. II. A comparison between incident and transmitted light fluorescence for the detection of specific IgM antibodies

The fluorescence obtained with an incident light system is higher than that obtained with a transmitted light system. Examination time is reduced and the strain on the eyes, after long periods, is reduced. However, the results are the same whatever the system used.

[Osteoid osteoma of the phalanges]

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