Experimental uremia. Description of a model producing varying degrees of stable uremia

A model is described for the induction in the rat of varying degrees of stable uremia using controlled resection of renal tissue. Three degrees of uremia have been attained: 'mild--blood urea 40--80 mg/100 ml (6.68--13.36 mmol/1); 'moderate'--blood urea 100--200 mg/100 ml (16.7--33.4 mmol/1), and 'severe'--blood urea greater than 200 mg/100 ml (> 33.4 mmol/1). Mild uremia was produced by unilateral nephrectomy; moderate uremia required the resection of 80 +/- 2% of the total renal mass, and severe uremia was produced by 88 +/- 2% nephrectomy. A sham-operative procedure provided an appropriate control for the model. Evaluation of the model has been carried out using analyses of renal function (GFR, concentrating capacity), blood biochemistry, hematological parameters and histological examination. The ability to induce a standardized, stable uremia at predetermined levels, uncomplicated by the administration of nephrotoxic material, represents an advance on existing methods for producing experimental renal failure.

Radiology of the acute surgical abdomen in infants and young children

The most common nontraumatic acute surgical lesions of the infant abdomen are considered. These abdominal lesions are divided into those which do and do not cause bowel obstruction. Lesions causing bowel obstruction are almost always identified as being surgical and are usually appropriately treated. Most common in this group are incarcerated inguinal hernia and malrotation. Among the non-obstructive lesions, appendicitis is the most common and frequently very difficult to diagnose in this age group. The early use of a barium enema is advocated if appendicitis is a diagnostic possibility. Profound ileus can be seen in a variety of medical conditions and several examples are cited.

Permselectivity of cat blood-lymph barrier to endogenous macromolecules

The restrictive properties of liver blood-lymph barrier to endogenous plasma protein fractions of varying molecular size were studied at different hepatic venous pressures (and lymph flows) using steady-state lymph to plasma protein concentration ratios. At control hepatic venous pressures (0-2 mmHg) the lymph to plasma venous concentration ratios of the various protein fractions indicate significant selectivity by the liver blood-lymph barrier to macromolecules on the basis of molecular size. The sieving observed was consistent with equivalent pore radii of 180-250 A. The transsinusoidal oncotic pressure gradient ranged between 4.0 and 8.0 mmHg at control venous pressures. As venous pressure was increased, liver lymph flow and lymph to plasma protein concentration ratio increased while the blood-lymph oncotic pressure gradient decreased. Liver lymph flow was linearly related to hepatic venous pressure. At lymph flow less than or equal to 10 x control, there is no longer a sieving effect on plasma protein; findings consistent with por radii in excess of 1000 A. The results of this study suggest that maximal sieving by the liver blood-lymph barrier occur at normal capillary filtration rates and support the possibility that the interstitium is the rate limiting barrier for blood to lymph transport of macromolecules in the liver.

Adrenocortical function and a field population of a macropodid marsupial (Setonix brachyurus, Quoy and Gaimard)

Concentrations of corticosteroids and aldosterone have been measured in the plasma and related to the maximum cortisol binding capacity, to the concentration of sodium and potassium of the plasma and to the condition of the animals, in a natural population of the quokka (Setonix brachyurus, Quoy & Gaimard) on Rottnest Island, Western Australia. A marked population in one area has been repetitively sampled at approximately 6 week intervals over a period of 2 years. Animals were found to be in significantly better condition during the hot-dry season. Their plasma concentrations of corticosteroids, 1.09 +/- 0.11 (S.E.M.) and 1.47 +/- 0.14 microgram/100 ml and their plasma sodium concentrations, 147 +/- 0.87 and 142 +/- 1.17 mequiv/1, for the hot-dry and cold-wet seasons respectively, were both significantly different (P less than 0.05). Plasma concentrations of aldosterone were 8.40 +/- 0.57 and 7.06 +/- 0.53 ng/100 ml for the hot-dry and cold-wet seasons. The level of aldosterone fell to levels comparable to those found in salt-replete laboratory animals only during the month of July. In the laboratory, salt deprivation resulted in a significant rise in the concentration of plasma aldosterone, 2.33 +/- 0.57 (S.E.M.) ng/100 ml when salt-replete and 16.95 +/- 2.74 ng/100 ml when salt-deprived (P less than 0.001). Total plasma corticosteroid levels were unaffected by changes in the sodium content of the diet. Injections of ACTH at a rate of 2 i.u./kg caused a significant rise in the levels of plasma corticosteroids which were essentially identical in both high- and low-condition animals. Both temperature fell to a significantly lower level in low-condition animals held in cages after injection of ACTH. These results indicate that the seasonal mortality of th quokka on Rottnest Island does not result from any breakdown in adrenal function, despite a substantial decline in the condition of the animals.

B lymphocyte colony formation in renal infection

The effect of renal infection on B lymphocyte colony formation has been investigated in the belief that a study of the effect of infection on subpopulations of lymphoid cells might provide direct evidence of the effect of infection on the immmune system. Renal infection was induced in mice, and the specific immune response of the B lymphocyte compartment was quantitated by determining the serum antibody and plaque-forming cell response to infection. Under the conditions of the experiment, the ability of splenic lymphocytes to form B lymphocyte colonies was significantly depressed during the first 7 days of infection, and the results suggest that a study of the responses of lymphoid cells to infection may provide information of diagnostic and prognostic value.

Immunoglobulins and hyposensitization for allergy

The premise that protracted stimulation of the human immune system might be involved in the induction of malignant immunocytopathies is scrutinized. Studies of the serum immunoglobulins of 313 patients who had been hyposensitized for allergy are compared with those of 138 nonallergic and 189 allergic individuals not subjected to this therapy. Critical historical data in all groups are also evaluated. The investigators concluded that, as far as the parameters studied, there were significant differences in the mean total immunoglobulin G levels in allergic hyposensitized persons compared with the non-allergic control group. It involved a depression of the serum IgG concentration and related to the length of the desensitization program and to whether it was continuous or interrupted. One evolving monoclonal immunocytopathy, etiology of which has not been established, was encountered during the period of study.

Intrauterine diagnosis of fetal disease by x-ray

Images

99m technetium sulphur colloid localization in renal infection. An experimental evaluation

Renal uptake of 99mTechnetium sulphur colloid (99mTcSC) was investigated in 99 animals with experimentally induced unilateral pyelonephritis and in 60 animals with a thermally induced renal injury. The degree of localization of 99mTcSC in the kidney was determined by direct counting of retained isotope after bilateral nephrectomy at autopsy. Phagocytosis of 99mTcSC by inflammatory tissue has been reported and it was anticipated that renal infection would lead to an increase in 99mTcSC uptake by the kidney. In fact it was found that renal infection with pathologic changes resulted in a significant decrease in the localization of 99mTcSC in the pyelonephritic kidney. A similar decrease was found in the thermally injured kidney but renal infection without pathologic changes did not give rise to any changes in radionuclide uptake. These findings suggested that phagocytosis by the proximal convoluted tubular cells is the normal mechanism for 99mTcSC accumulation in the kidney and that renal infection reduced the phagocytic capability of these cells.

Modification by suppressor cells and serum factors of the cell-mediated immune response in experimental pyelonephritis

A marked suppression of the thymusderived (T)-lymphocyte response to concanavalin A has been demonstrated in vitro during renal infection. Suppression of the T-lymphocyte response in vitro was seen as early as 2 h after the induction of renal infection, but maximum suppression was found 24-72 h later. A population of suppressor cells in the splenic lymphocyte population, generated during the host's response to infection, contributed to the depressed lymphocyte response. Removal of suppressor cells restored the mitogenic responsiveness of the remaining splenic lymphocytes. Conversely, in co-culture experiments, a suppressor cell present in the splenic lymphocyte population of pyelonephritic animals was shown to be capable of suppressing the mitogenic responsiveness of normal splenic lymphocytes. Significantly reduced host vs. graft responses by the pyelonephritic animals confirmed, in vivo, the depression of cell-mediated immune mechanisms. An additional suppressive factor was found in the serum of pyelonephritic animals which depressed in vitro the mitogenic responsiveness of splenic lymphocytes from normal animals. Support for the suppressive role of this serum factor was found when splenic lymphocytes from pyelonephritic animals were tested in vivo in the absence of homolgous serum (graft vs. host). Under these conditions, the lymphocytes showed an enhanced reaction compared with lymphocytes from normal animals. The presence of a suppressor cell population and a serum factor, both capable of depressing cell-mediated mechanisms, may be major factors contributing to the establishment of infection in the kidney.

Intermittent dislocation of the liver. A syndrome associated with volvulus of the transverse colon and stomach and obstructive jaundice

Displacement of the right lobe of the liver into the left upper abdominal quadrant can occur only if the diaphragmatic attachments are congenitally absent or traumatically disrupted. To our knowledge, the former situation has not been previously described in an adult patient. A young man with a lifelong history of unexplained intermittent, bizarre upper abdominal pain was found to have a freely movable right lobe of the liver that was attached only to the inferior vena cava. When this lobe was intermittently displaced into the left upper abdomen, volvuli of both the stomach and transverse colon developed. Stretching and tension of the common bile duct on the round ligament resulted in intermittent jaundice. At operation, these findings were confirmed, and the right liver lobe was secured to the diaphragm in its normal position. In addition, the mesenteric attachments of the liver, stomach, and colon were plicated. The patient has had complete relief of all symptoms for the two years since his operation.

Effects of spontaneous and artificial membrane rupture in labour upon fetal heart rate

This study reports the effects of spontaneous rupture of membranes and artificial rupture of membranes on fetal heart rate patterns during labour in 87 normal and 25 complicated pregnancies. The incidence of early deceleration patterns following membrane rupture was 6.25 per cent during the first 15 minutes and 1.78 per cent after 45 minutes, regardless of whether the pregnancy was normal or complicated. It is concluded that rupture of membranes does not significantly increase the incidence of early deceleration patterns. However, the occurrence of other heart rate alterations such as late decelerations, loss of beat-to-beat variability, changes in base line and tachycardia, need to be investigated further in larger collaborative studies.

Ear-cough (Arnold's) reflex

A clinical survey of 688 patients revealed an incidence of Arnold's reflex in 1.74% of a general otolaryngology clinic population. There was no definite age, sex, or racial correlation found. The reflex was found unilaterally as well as bilaterally and in each canal quadrant, which is contrary to the previously described distribution of the nerve to the posterior and inferior parts of the canal. There was no predilection of a positive reflex with any particular ear disease.

Studies on the neuropharmacological activity of bicuculline and related compounds

Bicuculline and 3 chemical derivatives were assayed on a variety of biological systems. Consistent with reports of studies on other animals, some of these compounds caused convulsions in insects and blocked inhibitory postsynaptic potentials in insect muscle. They all potently inhibited mouse brain acetylcholinesterase. Bicuculline and its analogs inhibited the binding of GABA in vitro to sites in crayfish muscle membranes which have properties of receptor sites; this site of action could explain the activity of bicuculline at arthropod neuromuscular junctions. These compounds, at high concentrations (over 100 muM), also inhibited GABA uptake by mouse brain homogenates at 0 degrees C apparently non-competitively. Bicucine methyl ester inhibited GABA transport by brain at 37 degrees C, consistent with non-specific membrane effects at high concentrations of drug. These and other observations cast doubt upon the specificity of bicuculline-like compounds for action on GABA synapses, especially for in vitro studies at high drug concentrations (over 10 muM). The neuroactivity of low doses of bicuculline is apparently not explained by these in vitro effects, and could very well be due to inhibition of GABA synapses at either receptor or ionophore sites. At physiological conditions of pH and temperature, bicuculline is hydrolyzed at its lactone moiety to the less active compound bicucine; this could lead to underestimates of the biological activity of bicuculline. More stable analogs studied so far are not more potent, however.

Determination of glomerular filtration rate in the rat using 51Cr-EDTA and a single blood sample

51Cr-labeled ethylenediaminetetraacetic acid (EDTA) was used to measure the glomerular filtration rate in rats using external body counting and a two-compartmental analysis according to the method of Sapirstein. A comparison was made of results calculated using the two-compartment method and a recently proposed formula requiring a knowledge of the distribution volume of the isotope and the analysis of a single timed plasma sample. The results have shown that the formula of Bryan et al. can be used for the rapid and convenient determination of glomerular filtration rate in small animals after the administration of 51Cr-EDTA.

Synovial sarcoma of the larynx

There have been several reports in the literature2-5 of synovial sarcomas of the head and neck. The consensus of these authors is that the tumor is not as aggressive in this localization as in the extremities, where the recurrence rate is 60% to 70%, and the five-year long-term follow-up of such cases should be made available. Thereby, a reasonably clear and effective modality of treatment could be recommoneded.

Selective deficiency of thymus-derived lymphocytes in experimental pyelonephritis

Pyelonephritis was induced in experimental animals derived of thymus-derived (T) lymphocytes by adult thymectomy and serial sublethal irradiation. In this model T lymphocytes were reduced to less than 1% of normal adjudged by the in vitro Phytohemagglutinin (PHA) responsiveness of lymphoid cells from deprived animals compared with control animals. Pathologic, bacteriologic and immunologic aspects of renal infection were studied in the T cell-deprived animals during the acute, resolving and chronic stages of pyelonephritis. The experiments have shown that the ablation of lymphocytes did not appreciably alter the course of the disease.

Water and electrolyte replacement during repeated days of work in the heat

In an attempt to determine the value of replacing sweat losses with and electrolyte solution, 12 subjects (2 women and 10 men) were dehydrated (minus 3% body weight) on 5 successive days. During one 5-d sequence, the subjects replaced fluid losses with a glucose-electrolyte solution, while water was the only fluid ingested during a second 5-d series. With the exception of the drink, daily ionic and caloric intakes were identical for the two 5-d conditions. Measurements of water and electrolyte losses in sweat and urine showed a positive balance in body Na+, K+, and Cl- during both the water (W) and electrolyte solution (ES) treatments. Subjects accumulated significantly more Na+ during the W experiments (392 mEq/5 d) than when the electrolyte solution was ingested (334 mEq/5 d). As a result, the extracellular fluid compartment, represented by plasma volume, increased 12.2 and 9.0% during the 5-d sequence of the W and ES trials, respectively. It was concluded that the addition of electrolytes to drinking water is of minimal value for subjects who dehydrated (-3%) on repeated days and are permitted to ingest food and drink libitum

Surgical repair of facial nerve branches. An analysis of different sheathing and suturing techniques

The distal branches of the facial nerve are sometimes severed in various forms of trauma. These distal branches respond to repair differently than do the main trunk or other peripheral nerves. Actual axon counts must be done to determine the percentage of regrowth rather than measuring nerve diameter. Physiologic and histologic techniques were used to analyze sheathing and suturing techniques in the repair of facial nerve branches in rabbits. Repair sites were examined at various intervals up to four months after repair. Very small suture material (10-0) must be used. Vein sheaths caused decreased axon regrowth, and strictures occurred when silicone elastomer sheaths were used. Seven stitches provided the best results in terms of axon regrowth, prevention of neuromas, and return of function. Three sutures or a continuous stitch produced poorer overall results.