Hereditary deficiency of lactate dehydrogenase M-subunit

A family with a complete deficiency of lactate dehydrogenase M-subunit was investigated. The propositus was an 18-year-old male who complained of exertional pigmenturia and easy fatigue. Marked discrepancy was observed in the ratio between creatine kinase and lactate dehydrogenase (CK/LDH). Electrophoretic analysis of serum LDH isoenzymes of the propositus demonstrated only one activity band of LDH H4. A complete lack of the LDH M-subunit was similarly demonstrated in erythrocytes, leukocytes and in the intermediate vastus muscle. LDH levels in the muscle specimen were markedly decreased in the patient, whereas CK and aspartate aminotransferase were almost the same as in a control subject. LDH isoenzymes of erythrocytes were analyzed in 5 siblings and in the parents. This demonstrated a complete lack of LDH M-subunit in 3 siblings. The ratio between H-subunit and M-subunit (H/M) in erythrocyte LDH suggested a partial absence of the M-subunit in two siblings and in the parents. An abortive increase of blood lactate and a marked increase in blood pyruvate were observed immediately after ischemic work of the forearm, accompanied by an increase in serum creatine kinase and myoglobinuria. The present case represents a newly described form of genetically determined myopathy.

Specific features of smooth muscle cells recorded from the placental region of the myometrium of pregnant rats

The muscle membrane and contractile properties of placental and non-placental regions of pregnant and postpartum myometria of the rat were investigated.1. The membrane potential of the myometrium varied during the progress of gestation, but the membrane potential in the placental region was consistently higher than that in the non-placental region up to the last stage of gestation. The maximum difference in the membrane potential recorded from both regions was observed at 17-21 days gestation.2. The conduction velocity of the excitation measured from muscle cells of the non-placental region was consistently larger than that of the placental region at any stage of the gestation (7-22 days). At 7 days gestation, the conduction velocity in the placental region could not be measured due to widely scattered values of the latencies for the spike generation. During the progress of gestation, the conduction velocity increased, and the value was consistently larger (about 10 times) in the nonplacental region than that in the placental region at any stage of gestation up to the last stage.3. The length constant of the tissue measured from the non-placental region was larger (2.3 mm) than that in the placental region (1.1 mm) at 14 days gestation. The propagation of the excitation seems to be blocked from the cells of the non-placental region to the placental region, but not vice versa.4. The shape of the spike in the non-placental region changed markedly during the progress of gestation. The spike could be recorded from the cells of the placental region but not consistently. However, the electrical activity of muscle cells recorded at the full term was much the same in both regions.5. Various concentrations of [K](o) or [Na](o) modified the membrane potential. The differences in the membrane response to the above ionic environments appeared more significantly at the different stages of gestation, rather than topical differences.6. Sensitivity of the muscle cell membrane to oxytocin in the placental region was higher than that in the non-placental region at any stage of gestation, while that to prostaglandin F(2alpha) was much the same in the cells recorded from both regions.7. At 8 days gestation, the circular muscle layer is lost from the area of implantation and only the longitudinal muscle layer remains. The width of the placenta and the thickness of the muscle layer increased during the progress of gestation.8. From the above results, the role of smooth muscle cells in the placental region is discussed in relation to hormonal controls in the myometrium, i.e. the activity of the muscle cell membrane in the placental region was markedly suppressed up to the last stage of gestation, however, there was no apparent direct relation between the inhibitory responses and the actions of progesterone.

Resealing of erythrocyte membranes after hypotonic hemolysis

A new quantitative method to study kinetics of resealing of erythrocyte membrane, defined as the recovery of impermeability to dextran, was established. Erythrocyte membrane pre-labelled with 125I were incubated under various conditions. Sealed and unsealed membranes were separated using dextran density gradient centrifugation. Sealed membranes which are impermeable to dextran were recovered from the top of the centrifuge tube, while unsealed membranes were recovered from the bottom of the tube. Degree of resealing was calculated from the counts of 125I recovered from sealed membrane fraction. The resealing of membrane from human erythrocyte after hypotonic hemolysis was dependent on the incubation temperature. Resealing was rapid above 30 degrees C, while it was not observed below 20 degrees C. The process completed within 1 hr at 37 degrees C. Ionic strength of the medium is also an important factor which controls the resealing process. The effect of NaCl in the medium on resealing was biphasic. In the lower range of NaCl (0-50 mM) there was gradual decrease of resealing capacity. Above 50 mM, the capacity was again increased. The mode of resealing of sheep and rabbit erythrocyte membranes was rather different from that observed in human erythrocyte. Under the present experimental condition, these erythrocyte membranes did not reseal well. The immediate resealing, which is observed in human erythrocyte upon hemolysis in the presence of Mg++ or Ca++ ions, was observed neither in sheep erythrocyte membranes nor rabbit ones.

Studies on angiopathy due to carbon disulfide. Retinopathy and index of exposure dosages

The occurrences of retinopathy (microaneurysms/small dot hemorrhages) and the coded resting and postexercise ECG findings suggestive of coronary heart disease (CHD) were studied among 420 Japanese male workers exposed to carbon disulfide and 390 men not exposed to such a solvent. Retinopathy was detected in 24.4% of the exposed group and in 3.8% of the nonexposed group by color fundus photography. Among workers of the former group there was a significant correlation between retinopathy prevalences and the index of exposure dosages (r = 0.925, P less than 0.01). However, correlation between the prevalence of retinopathy and duration of exposure was not so high (r = 0.647, 0.10 less than P less than 0.25). The occurrences of coded resting and postexercise "coronary" ECG findings were not related to the index of exposure dosages. Some risk factors for CHD such as total serum cholesterol, triglycerides, beta-lipoproteins, blood pressure, obesity, and skinfold thickness were simultaneously studied. But these variables did not prove to be important in the development of angiopathy due to carbon disulfide, especially the so-called retinopathia sulfocarbonica.

Catecholamine-storing cells in the cyclostome heart

The lamprey heart contains characteristic catecholamine-storing cells in both the atrium and the ventricle. Sufficient circumstantial evidence is available indicating that catecholamines together with protein carbohydrate complexes are contained in these cells within the membrane bound cytoplasmic granules. If the "recepto-secretory function" and "neuroectodermal origin" of these cells are proved, then they may be classified as typical paraneurons.