Intermediate homocysteinemia: a thermolabile variant of methylenetetrahydrofolate reductase

A "newly detected" variant of methylenetetrahydrofolate (MTHF) reductase (E.C.1.1.1.68) deficiency associated with an 8-15-fold increase in plasma total homocysteine was discovered in two unrelated patients who had subnormal serum folate. However, the homocysteinemia was corrected by oral folic acid supplement. When MTHF reductase activities in lymphocyte extracts before and after heat treatment at 46 C for 5 min were compared, there was a consistent difference in heat stability between the enzyme from the controls and that from the patients. The mean residual activities after heat treatment were 37.0% (34.1%-42.6%) in the controls and 15.2% and 15.1% in the two patients, respectively. Two obligate heterozygotes for severe MTHF reductase deficiency had residual activities of 39.6% and 37.7%. A similar difference in thermostability was demonstrated in cultured skin fibroblasts and lymphoblasts. Studies with a mixture of lymphoblast extracts from a control and a patient and with partially purified enzyme suggested that the thermostability was an independent characteristic of MTHF reductase. These observations provided evidence of a hitherto undescribed mutant MTHF reductase in our two patients with intermediate homocysteinemia. Unlike previously reported patients with MTHF reductase deficiency, there was no apparent clinical problem related to the abnormal folate or homocysteine metabolism during infancy or childhood in these two subjects, but one of them had vascular disorders in adulthood. The observations in these two subjects suggested that a moderate deficiency of MTHF reductase might be associated with vascular disorders in adult life.

Transluminal catheter angioplasty of abdominal aorta in Takayasu's arteritis

Nine patients with Takayasu's arteritis and a long stenotic segment of the abdominal aorta were treated by percutaneous transluminal angioplasty (PTA). Intermittent claudication disappeared in six of seven cases, the femoral pulse reappeared in all five; ankle/arm indices increased in seven cases; elevated blood pressure normalized in seven of eight cases. Seven patients were followed for 3 to 28 months. They were all free of symptoms from the lower extremities. In three patients with or without renal artery stenosis and with hypertension, the blood pressure decreased after PTA of the abdominal aorta only. PTA may be a valuable treatment in Takayasu's arteritis and stenosis of the abdominal aorta.

Effect of low power laser irradiation on nociceptive cells in Hirudo medicinalis

The effect of low power Helium-Neon (He-Ne) and Gallium-Arsenide (Ga-As) laser on the nociceptors in Hirudo medicinalis was studied. The results show that low power laser irradiation does not: affect the membrane potential or the excitability of the nociceptive neurons, affect the mechanical pressure required to activate the nociceptors or their action potentials. The results indicate that the analgesic effects reported in humans with "laser-acupuncture" with similar modes of low power laser are likely not explained by effects on nervous tissue.

Low power laser irradiation does not affect the generation of signals in a sensory receptor

The effect of low power Helium-Neon (He-Ne) and Gallium-Arsenide (Ga-As) laser on the slowly adapting crustacean stretch receptor was studied. The results showed that low power laser irradiation did not affect the membrane potential of the stretch receptor. These results are discussed in relation to the use of low power laser irradiation on the skin overlaying acupuncture points in treatment of pain syndrome.

[Flow cytometer (FCM) in biological characteristics of nasopharyngeal carcinoma xenografts in nude mice]

Tumor tissue from a patient with nasopharyngeal carcinoma was transplanted to nude mice (BALB/c) and had successfully been maintained through ten passages. The nude mice tumor and the primary human tumor were assayed by FCM for the DNA content in addition to conventional pathological examination, chromosome analysis and EBV assay. The tumor incidence in the different passages showed a marked change ranging from 25% to 81% with a mean value of 52% which tended to increase, however. The doubling time of six tumors in the ninth passage showed no great change 6-12 weeks after transplantation with a mean about 4.3 days. But at week 12, there was a significant difference between each tumor volume, ranging from 438 to 1,998 mm3. By FCM, it was found that the DNA index remained constant in both the primary and nude mice tumors. Among the nude mice tumors in different passages, the distribution of various phase cells in cell cycle was similar to that of the primary tumor. In conclusion, the use of FCM to assay the cellular DNA content in nude mice tumor is rapid and sensitive. It is helpful, for the nude mice tumor, in identifying stability of the biological characteristics and in studying of the mechanism of chemotherapy and radiotherapy in the future.