Effect of dietary urea on blood pressure in spontaneously hypertensive rats

The feeding of a normal diet containing 13.5% urea (in place of protein in a high protein diet) attenuated the development of severe hypertension and decreased the incidence of stroke in spontaneously hypertensive rats (SHR), when 1% NaCl solution was given to them. The urea not only increased urine volume, but also increased urinary sodium excretion in SHR given 1% NaCl for drinking. Although there was no obvious difference in erythrocyte size between the urea and the control groups, there was a significant inverse correlation between plasma urea level and erythrocyte size. These results suggest that a high protein diet reduced blood pressure partly through the diuretic effect of urea, the common metabolite of various proteins.

Nuclear transplantation in teleosts. Hybrid fish from the nucleus of crucian and the cytoplasm of carp

Hybrid fish are obtained from the combination of nucleus and cytoplasm from two genera of fresh-water teleosts using the technique of nuclear transplantation (i.e. the combination of the nucleus of crucian (Carassius auratus) and the cytoplasm of carp (Cyprinus carpio]. Morphological characteristics of these hybrid fish that have been examined so far indicate that some features such as barbs, pharyngeal teeth, the number of scales along the lateral line, and the number of vertebrae are similar to those of crucian. Some of the hybrid fish grow to normal adult fish.

Myelography in achondroplasia: value of a lateral C1-2 puncture and non-ionic, water-soluble contrast medium

Because of technical difficulties and diagnostic limitations encountered with other myelographic techniques in patients with achondroplasia, the authors employed a lateral C1-2 puncture and non-ionic, water-soluble contrast medium in 18 achondroplastic patients with spinal compression (21 procedures). This technique proved most appropriate for identifying the upper limit of degenerative osteophytes causing exacerbation of congenital spinal stenosis, which is crucial in planning decompressive surgery. A potentially important additional finding was the presence of degenerative lower cervical spine disease in the majority of patients. There were no serious complications. The authors recommend this technique as safe and effective in achondroplastic patients with severe congenital spinal stenosis.

Electrical charge. Its role in the pathogenesis and prevention of experimental membranous nephropathy in the rabbit

Intravenous cationic bovine serum albumin (BSA, pI > 9.5) induces membranous nephropathy in immunized rabbits. In this study, unimmunized rabbits received intravenous injections of cationic (n = 3) or native (n = 3) or native (n = 3) BSA, followed by ex vivo isolated left renal perfusions with sheep anti-BSA antibody. Capillary wall deposits of IgG and C3 were seen exclusively in the group receiving cationic BSA, confirming an in situ pathogenesis for cationic, BSA-induced membranous nephropathy, and demonstrating the importance of a cationic antigen for its production. We then explored whether membranous nephropathy in this model is prevented by the concomitant injection of protamine sulfate, a filterable, relatively non-immunogenic polycation. An in vitro study demonstrated that protamine sulfate incubated with glomerular basement membrane (GBM) decreased the subsequent binding of radiolabeled cationic BSA (P < 0.05). In vivo, protamine sulfate was shown to bind to anionic sites in the glomerular capillary wall after intravenous injection.Groups of rabbits received 3 wk of daily intravenous injections of cationic BSA alone (n = 15) or cationic BSA and protamine (n = 18). After 2 wk of injection of cationic BSA alone, typical membranous nephropathy developed. Granular deposits of IgG and C3 were present along the GBM associated with subepithelial dense deposits, foot process effacement, and marked albuminuria. Protamine significantly reduced or prevented the formation of deposits (P < 0.001) and in6 of 18 protamine-treated animals, existing deposits decreased or disappeared between 2 and 3 wk of injection. Albuminuria was significantly reduced in protamine-treated animals with a mean of 124+/-55 mg/24 h compared to 632+/-150 mg/24 h in the control group receiving cationic BSA alone. No significant differences between the groups were noted in serum lev9lsof IgG, C3, anti-BSA antibody, or circulating immune complex size. Studies in additional animals (n = 5) given radiolabeled cationic BSA showed that protamine did not alter the clearance of cationic BSA from serum. Control experiments showed that protamine's beneficial effects were not related to its weak anticoagulant property or toits theoretical ability to deplete tissue histamine. The administration of heparin (n = 6) or diphenhydramine (n = 6) had no effect on the development of the epimembranous lesion compared to the group receiving cationic BSA alone. In addition, homogenized whole kidney histamine content was not significantly different in the group receiving cationic BSA alone compared to the group receiving cationic BSA and protamine. This work shows that a cationic BSA-induced glomerular lesion can be produced by a renal perfusion technique involving in situ complex formation and that this process requires a cationic antigen for its development. We believe that the demonstrated beneficial effects of protamine are due to its ability to bind to glomerular anionic sites, and that this electrostatic interaction results in inhibition for the further binding of the cationic antigen, thereby limiting the severity of glomerulonephritis in this model.

Multilevel disease of the conduction system

We found that the incidence and distribution of conduction system disease simultaneously affecting several levels of the system had been incompletely described. We therefore analysed all patients in whom conduction disease had been diagnosed and a complete electrophysiological study of the conduction system had been made, during a defined period. Patients were classified as to the presence or absence of sinus node disease, and proximal and distal atrioventricular disease. Since our hospital serves a defined population and a large proportion of all patients with conduction disease seen during the period was included, the series probably is representative of conduction disease in general. Twenty-four of the 59 patients had defects at more than one of the three levels (41%). Fifty-five per cent of the patients with sinus node disease had some kind of atrioventricular disease, while 42% of the latter had evidence of sinus node failure. The patients with multilevel disease were characterized by more severe symptoms, higher age and a higher incidence of generalized heart disease than those with single-level disease. The observations fit the concept that conduction system disease in most patients is part of a diffuse disease process progressively involving various parts of the system.

Hepatic damage in experimental and clinical paragonimiasis

The hepatic damage induced by Paragonimus skrjabini, and the migration route of this species and that of P. westermani, were investigated in a series of animal experiments and in 34 clinical and four autopsy cases of paragonimiasis. The major symptoms and signs of an unique case reported from Sichuan Province included hepatic tenderness, disturbance of hepatic functions, remittent fever, and cough with bloody sputum. Laparotomy revealed marked adhesions surrounding the liver, spleen and duodenum. Diagnosis was made by finding P. skrjabini in a bulla on the abdominal wall about 5 months after the onset of illness. After specific treatment with bithional, body temperature and liver functions returned to normal. Twenty-three of 33 cases independently studied from Fujian Province also showed similar hepatic function disturbance. Autopsy cases showed hepatic chronic eosinophilic abscesses with Charcot-Leyden crystals. Experimentally, P. skrjabini infection caused hepatic damage in all laboratory animals used. The main pathologic changes were initially acute eosinophilic abscesses in the liver, worms being found sometimes in the necrotic cavities of the abscesses; hepatomagaly also occurred. Some cysts containing mature worms were found in the liver of dogs 3-9 months after infection. Numerous eggs were deposited in the cyst walls. The migration route of P. skrjabini was studied in young dogs. Worms appeared in the liver initially on day 3 and reached their highest level on day 14. P. westermani also migrated into liver, but their numbers were less than those of P. skrjabini.

The nature of CuA in cytochrome c oxidase

The isolation and purification of yeast cytochrome c oxidase is described. Characterization of the purified protein indicates that it is spectroscopically identical with cytochrome c oxidase isolated from beef heart. Preparations of isotopically substituted yeast cytochrome c oxidase are obtained incorporating [1,3-15N2]histidine or [beta,beta-2H2]cysteine. Electron paramagnetic resonance and electron nuclear double resonance spectra of the isotopically substituted proteins identify unambiguously at least 1 cysteine and 1 histidine as ligands to CuA and suggest that substantial spin density is delocalized onto a cysteine sulfur in the oxidized protein to render the site Cu(I)--S.

Transfer of radiation-induced spins from deoxyribonucleic and thymidylic acids to propyl gallate

When calf thymus deoxyribonucleic acid (DNA), propyl gallate (PG) and their five molecular mixtures (with PG content of 1, 2, 5, 10 and 20%) are irradiated with gamma-rays in dry state in vacuum at 296 degrees K, the ESR spectra of all molecular mixtures differ strikingly from those of DNA, but bear a close resemblance to those of PG. The spin yield in the PG contained in these mixtures is two to three orders of magnitude higher than that in the case of PG irradiated separately. Furthermore, on the basis of the relative saturation characteristics of ESR spectra, these molecular mixtures behave more like PG than like DNA. It may be inferred that the radiation-induced spins could be transferred from DNA to PG. With r representing the molar ratio of nucleotides to PG, we have found a good linear correlation between the transfer ratio (TR) and square root of r. One PG molecule could protect at least 68 nucleotides in the duplex DNA chain, and thereby the minimal range of spin transfer is estimated at 115 A. Results obtained from irradiation at 77 degrees K show that PG exerts no protective effect on DNA, so DNA sustains an irreversible damage. It is thought that the spin transfer from DNA to PG is exclusively due to a hydrogen transfer mechanism. We have also demonstrated the transfer of radiation-induced spins from both thermally denatured DNA and TMP to PG. The former process can be ascribed primarily to the hydrogen transfer mechanism, whereas the latter, as in the case of native DNA, exclusively to this mechanism.

Cyclic AMP metabolism and lipolysis in cultured human adipocyte precursors

Triacylglycerol breakdown (lipolysis) results from a series of reactions culminated by activation of "hormone-stimulated" triacylglycerol lipase, an enzyme unique to adipose tissue. We have studied various components of the lipolytic process in human omental adipocyte precursors differentiating in culture. The levels of cyclic AMP, the "second messenger" of lipolytic hormones, were about sixfold higher in fat cell precursors than those in abdominal skin fibroblasts. L-Isoproterenol resulted in significant elevation of cyclic AMP levels in both cell types. Preincubation of intact adipocyte precursors with insulin resulted in significant enhancement of "low Km" cyclic AMP phosphodiesterase activity; in contrast, this hormone had no effect on fibroblast phosphodiesterase activity, a distinctive biochemical difference despite the morphological similarities between the two cell types during the early stages of adipocyte precursor maturation. Incubation of adipocyte precursors with isoproterenol resulted in the release of fatty acids into the medium, findings indicative of "hormone-stimulated" lipase activity and, hence, the operation of the entire "lipolytic cascade"; isoproterenol-stimulated lipolysis was inhibited by insulin. Release of fatty acids from fibroblasts was not observed. Thus, "hormone-stimulated" lipolysis and insulin stimulation of cyclic AMP phosphodiesterase activity are expressed during early stages of human adipocyte precursor differentiation.

Role of sustained neurones of cat lateral geniculate nucleus in processing luminance information

The properties of the sustained cells in the lateral geniculate nucleus of cat have been studied quantitatively. These cells may be subdivided into two groups, the brightness and the darkness detectors. The former is photoexcitatory neurone and the latter, photoinhibitory. In both types, the rates of sustained discharges are closely related to the levels of retinal illumination over a range about 4 log units. The receptive fields of sustained cells again can be roughly divided into two subtypes according to their size. The large receptive field cells all belong to darkness detectors and are distributed mostly at retinal periphery, which may play some role in signalling the background luminance. The small receptive field cells comprise all brightness detectors and a part of darkness detectors, which are located predominantly around area centralis and may transmit the message of brightness or darkness about picture details and enhance the boundaries of a two-dimensional figure.

A supernumerary "G" like chromosome originating from a maternal 13;15 translocation in a nondysmorphic, retarded girl

This paper describes a retarded girl who had a severe seizure disorder and a few minor anomalies, and who was found to have a "G-sized" supernumerary chromosome in all her cells which were examined. Studies of the patient's and her parents' chromosomes by a variety of techniques suggest that the supernumerary chromosome arose following a prezygotic maternal 13;15 translocation.