Effects of Acute Lead Acetate Exposure on Adult Guinea Pigs: Electrophysiological Study of the Inner Ear

The effects on humans of lead acetate exposure may involve thecranial nerves, since vertigo and sensory neuronal deafnesshave been reported in lead workers; however, there exist onlya few reports concerning the dose effects of lead acetate bothon the cochlea and the eighth cranial nerve. The effects oflead acetate on the cochlea and the eighth nerve were investigatedsystematically using cochlear microphonics (CM), wholenerveaction potential (AP), and endocochlear potential (EP) in guineapigs (male albino Hartley). Guinea pigs were injected with 2ml of a 1% solution of lead acetate (20 mg) once a week for1–5 weeks. The threshold of whole-nerve AP (N₁) was elevatedby injection of lead acetate, even 40 mg, and whole-nerve AP(N₁) output voltage decreased after injection of 100mg of leadacetate. On the other hand, no change was observed in CM afterlead acetate injection (100 mg) or in EP after lead acetateexposure (40 mg). The blood concentrations of lead acetate wereas follows (mean): control, 4.5 µg/dl; Expt 1, 80 µg/dl;Expt 2, 126 µg/dl; Expt 3, 142 µg/dl;. We concludethat dysfunction of the eighth nerve is induced by high-doselead exposure, but that lead exposure does not induce electrophysiologicaldysfunction of the organ of Corti and the stria vascularis.     

Factor XI contributes to thrombus propagation on injured neointima of the rabbit iliac artery

BACKGROUND: Thrombus formation through the activation of tissue factor (TF) and factor (F) XI is a critical event in the onset of cardiovascular disease. TF expressed in atherosclerotic plaques and circulating blood is an important determinant of thrombogenicity that contributes to fibrin-rich thrombus formation after plaque disruption. However, the contribution of FXI to thrombus formation on disrupted plaques remains unclear. METHODS: A mouse monoclonal antibody against FXI and activated FXI (FXIa) (XI-5108) was generated by immunization with activated human FXI. Prothrombin time (PT), activated partial thromboplastin time (APTT), bleeding time, and ex vivo platelet aggregation in rabbits were measured before and after an intravenous bolus injection of XI-5108. We investigated the role of FXI upon arterial thrombus growth in the rabbit iliac artery in the presence of repeated balloon injury. RESULTS: The XI-5108 antibody reacted to the light chain of human and rabbit FXI/FXIa, and inhibited FXIa-initiated FXa and FXIa generation. Fibrin-rich thrombi developed on the injured neointima that was obviously immunopositive for glycoprotein IIb-IIIa, fibrin, TF, and FXI. Intravenous administration of XI-5108 (3.0 mg kg(-1)) remarkably reduced thrombus growth, and the APTT was significantly prolonged. However, PT, bleeding time and platelet aggregation were not affected. CONCLUSIONS: These results indicate that plasma FXI plays a potent role in thrombus growth on the injured neointima. Inhibition of plasma FXI activity might help to reduce thrombus growth on ruptured plaques without prolonging bleeding time.     

Serum erythropoietin levels for predicting bone marrow recovery following chemotherapy in leukaemia

Summary To investigate whether serum erythropoietin (EPO) levels are influenced by the intensity of bone marrow erythroid activity, we used a radioimmunoassay (Nippon DPC Co., Japan) to study EPO levels in three acute leukaemia patients during treatment with intensive chemotherapy. We also measured the reticulocyte count and reticulocyte maturity using an automated reticulocyte analyser (Sysmex R-2000) to detect erythropoietic activity. From the day after the initiation of chemotherapy, EPO levels increased markedly without any change in Hb levels, suggesting that some other mechanism was regulating serum EPO. A decrease in EPO after chemotherapy was accompanied by an increase in high fluorescence ratio, an index of immature reticulocvtes, but the actual increase in the reticulocyte count was delayed for 3-4 days after this. These findings suggest that the decrease in serum EPO levels was closely related to the early stage of red cell production and that EPO levels may be a useful marker for the recovery of erythropoietic activity after chemotherapy.     

Treatment of atelectasis of upper lung lobes. Selective bronchial suctioning with J-shaped catheter tip and guide mark

We developed a technique for blind bronchial suction using a curved-tip catheter with a guide mark, for the treatment of atelectasis of the lower and middle lobes of the lung. Suction of the upper lobe bronchi could not be performed because of the combination of the peculiar anatomy of the upper lobe bronchi with catheter design. We treated successfully two cases of atelectasis of the right upper lobes using a Rusch Metras bronchography catheter with a guide mark which is not readily available. Therefore we devised a J-shape tipped catheter with a guide mark. We have successfully treated 13 episodes of atelectasis of the right upper lobe in 10 patients and one episode in the left upper lobe in one patient with this new catheter.     

The effect of ultraviolet (UVB and PUVA) radiation on the expression of epidermal keratins

Using a panel of monoclonal antibodies directed against keratins (PKK₂. CK8.12 and KL₁). the effects of ultraviolet B (UVB) and psoralen plus ultraviolet A (PUVA) irradiation on keratin expression in guinea-pig skin were examined immunohistoehemically. Following irradiation, whether by UVB or PUVA, rapid alterations in the distribution pattern of keratins were observed in the epidermis. The alterations included the induction of basal cell-type keratins (PKK₂ and CK8.12 staining) in the suprabasal layers, with concomitant reduction ofthe suprabasal-type keratins (KL₁ staining). These alterations in keratin expression were observed during the period when DNA synthesis appears to be accelerated by ultraviolet light exposure (5 h–5 days after LIVB, and 2–10 days after PUVA irradiation). Therefore, these changes are probably reflections ofa proliferative or regenerative state of keratinocytes. This explanation was supported by the result of an experiment involving tape stripping of the epidermal horny layers, which also accelerates DNA synthesis hy keratinocytes. Immunohistochemistry appears to be a useful and sensitive method of detecting the effect of ultraviolet light on keratinization.