Study of the effects of dopamine hydrochloride on alpha 1-adrenoceptors in rat kidney

We studied the number and affinity of catecholamine receptors in SD rat kidney by radioreceptor technique. The following conclusions were obtained: 1) By using 3H-prazosin, the numbers of alpha 1-receptor (Bmax) in rat renal cortex were greater than those in rat kidney medulla. As for affinity (Kd), the significance was not recognized between the two. Bmax of the rat renal cortex to 3H-prazosin binding was 96.1 fmol/mg protein, and Kd was 0.17 nM, and for the rat renal medullar these values were 44.5 fmol/mg protein and 0.13 nM, respectively. 2) By measurement of D1-receptor using 3H-SKF38393 in the rat renal cortex in the Scatchard plot analysis, positive cooperativity was observed under the low concentration of hot ligand which was less than 1 nM. But at the concentration of hot ligand over 1 nM, the plots showed a straight line. Bmax of the rat renal cortex to 3H-SKF38393 was 2.5 pmol/mg protein and Kd was 5.3 nM. 3) Based on displacement by dopamine for 3H-prazosin binding to rat renal cortex, it was surmised that high concentration of dopamine had an affinity to alpha 1-adrenoceptors. 4) There was no change in the Kd and Bmax of alpha 1-receptor in the rat renal cortex after incubation of samples with low concentration of dopamine. However, in the case of high concentration of dopamine, a remarkable decrease of the affinity (Kd) of alpha 1-adrenoceptor was observed.     

The in vitro fertilisation programme at Tygerberg Hospital and the University of Stellenbosch. Five years' experience, April 1983-January 1988

The results of the in vitro fertilisation programme at Tygerberg Hospital for the period April 1983 to January 1988 are presented. Of the 1117 laparoscopies performed, 825 patients reached the transfer stage. A live-birth rate of 9.3% was achieved. The pregnancy rate after transfer of 4 embryos was 25.9% compared with 15.4% after 2 embryos and 10.8% after 3 embryos (P = less than 0.0001). The multiple pregnancy rate was 2.8% in the group receiving 2 embryos and 11.7% and 10.4% in those receiving 3 and 4 embryos, respectively. Of the 77 successful pregnancies (90 babies), 1 baby died at 34 weeks' gestation as the result of abruptio placentae due to preeclampsia and 1 cot death occurred. The only congenital abnormality encountered was a cleft palate.     

Isolated cavernous bodies

Corpus cavernosography in a patient with erectile dysfunction revealed absence of communication between the 2 cavernous bodies. No similar case was found in a review of 100 consecutive cavernosograms or in the literature. The abnormality may be a source of error in pressure recordings or in intravenous injection of pharmaceutical agents.     

A new technique for assessing the efferent innervation of the human striated urethral sphincter

A technique is described for recording the electromyographic response of the striated urethral sphincter to transcutaneous magnetic stimulation of the brain and spinal cord. A series of 11 control patients have been studied and 3 examples of patients with neurological disease also are reported. The most reliable response was recorded after facilitated transcranial stimulation of the cerebral cortex, with the mean latency of the electromyographic response in the striated sphincter being 26.4 msec. (standard deviation 2.21). It is concluded that assessment of the latency of the striated urethral sphincter electromyographic response to transcranial magnetic stimulation may be a useful technique in the investigation of patients with disorders of micturition.     

Gallstone dissolution

Many methods are available for gallstone dissolution, including oral bile salts; cholesterol solvents such as mono-octanoin or methyl tert-butyl either; and calcium or pigment solvents such as EDTA and polysorbate. Which of these approaches will be appropriate for an individual patient depends on the type of stones; whether they are in the gallbladder or the bile ducts; whether access to the biliary tree is available; the patient's age and general medical condition; and the availability of necessary expertise. In the US, both chenodeoxycholate and ursodeoxycholate are now available. Ursodeoxycholate is more expensive but appears to produce fewer side effects and may be more efficacious. These agents are most effective in thin women with small floating, radiolucent cholesterol stones in a functioning gallbladder. Only about half of the small subset of patients will experience partial or complete dissolution of stones within a year. Stone recurrence and the potential toxicity of long-term therapy are problems with this approach. Therefore, for most patients, cholecystectomy, either in the traditional fashion or using a laparoscopic approach (see article later in this issue by Gadacz et al), is the most cost-effective and perhaps the safest option. Intragallbladder instillation of methyl tert-butyl ether probably will be applicable only to a small subset of patients, and treatment is likely to be followed by a high recurrence rate. In patients with retained common duct cholesterol stones and access to the biliary tree, mono-octanoin therapy is advantageous in that it can be initiated as soon as cholangiography demonstrates no extravasation. In properly selected patients, a 90% success rate with this technique can be expected within 7 days.     

Technetium-99-labelled methylene diphosphonate uptake scans in patients with dialysis arthropathy

Patients on long-term haemodialysis suffer from dialysis arthropathy due to the deposition of dialysis amyloid. We investigated the use of 99Tc-labelled methylene diphosphonate bone scans in 17 patients as a possible in vivo diagnostic technique. In most clinically affected joints, with the exception of shoulders and hands, there was increased radioisotope uptake consistent with uptake by periarticular bone. In addition, we describe intense soft-tissue uptake around some clinically affected large joints. In contrast, control groups of patients on haemodialysis without arthropathy and patients without renal failure did not have increased uptake. A semi-quantitative scale of uptake was devised, and the following correlations were significant: pain perception and isotope uptake score in the ankles and feet, and the number of radiological lesions and isotope uptake scores in the wrists and knees. The following sites where the radioisotope might bind in the affected joints are proposed: amyloid deposits, areas of soft-tissue calcification, or areas of increased bone turnover. It is concluded that whereas the scanning technique cannot make a definite diagnosis of amyloid and, therefore, cannot be expected to supersede histological diagnosis, it is a useful adjuvant investigation, of particular importance in those patients unable or unwilling to undergo biopsy.     

Effects of 1.32-μm Nd-YAG laser on brain thermal and histological experimental data

Considering that the 1.32-μm Nd-YAG laser should have physicothermal properties close to those of the CO₂ laser, a series of experiments were conducted on rat cortex (N = 51). Three laser wavelengths were compared: CO₂ laser (10.6 μm), 1.06-μm Nd-YAG, and 1.32-μm Nd-YAG lasers. For each shot, temperature measurements were recorded with an infrared thermographic videocamera. The digitized signals were figured as thermal profiles and temperature developments. Ninety-five shots were correctly studied and analyzed: CO₂, N = 29; 1.06-μm Nd-YAG, N = 20; 1.32-μm Nd-YAG, N = 46. The histological lesions produced by these three lasers were compared on animals killed 24 hours (N = 20), 8 days (N = 20), and 30 days (N = 5) after the laser impacts. For equivalent densities of energy, the depth of cortical necrosis was comparable for the CO₂ laser (200–250 μm) and the 1.32-μm Nd-YAG laser (210–260μm) whatever the date of death; the 1.06-μm Nd-YAG laser shots were responsible for much more important damage (400–550μm). Because of its important absorption in water and nervous tissue, the authors consider the 1.32-μm Nd-YAG laser most suitable for neurosurgery, particularly because it is conducted through optic fibers, and therefore is easy to handle during neurosurgical procedures.     

Liquid silicone as a lunate prosthesis

Eleven patients with lunatomalacia were treated by excision of the lunate and instillation of liquid silicone. The silicone vulcanised and formed an in-situ molded prosthesis. The patients were reexamined after a mean of 7.1 years. Four patients were pain-free and two had pain only at work; three had not been improved by the operation and two had undergone arthrodesis. The patients with good results all belonged to group IV pre-operatively. Surprisingly, no patient showed any sign of silicone synovitis, although all the prostheses except one had either fractured or deformed. The reasons for this are discussed and the indications for the operation established.     

Regional patterns of bone loss and altered bone remodeling in response to calcium deprivation in laboratory rabbits

Summary This study explores the effects of a calcium-deficient diet on patterns of bone remodeling, and examines regional differences in the amount of bone lost. Skeletally mature female rabbits (n=6) were fed a calcium-deficient diet (0.10% Ca²⁺ and 0.50% P) for 14 weeks. A separate group of rabbits (n=4) were fed a maintenance diet (1.2% Ca²⁺ and 0.45% P). Bone mineral content, serum calcium, and serum phosphorus were measured each week during the experimental period. Following sacrifice, the L₃ vetebra, femoral head, proximal tibial metaphysis, and tibial midshaft were analyzed histomorphometrically. Rabbits had 20% less vertebral bone after only 14 weeks of a calcium-deficient diet. As in human postmenopausal osteoporosis, bone loss in calcium-deficient rabbits occurs in the trabecular bone of the lumbar spine before that in the trabecular bone of the lower extremity. Calcium-deficient diets alone do not lead to increased osteoid volume or thickness. Because bone loss is relatively rapid and because the pattern of loss is similar in some respects to that found in humans, adult rabbits may provide an attractive model of calcium deficiency osteoporosis in a skeletally mature mammal in which remodeling is predominant over modeling.     

Load-induced proteoglycan orientation in bone tissuein vivo andin vitro

Summary Previous studies of Alcian blue-induced birefringence in adult avian cortical bone showed that a short period of intermittent loading rapidly produces an increased level of orientation of proteoglycans within the bone tissue. In the absence of further loading, this persists for over 24 hours. We have proposed that this phenomenon could provide a means for “capturing” the effects of transient strains, and so provide a persistent, constantly updated strain-related influence on osteocyte populations related to the bones' averaged recent strain history, in effect, a “strain memory” in bone tissue. In our present study, we use the Alcian blue-induced birefringence technique to demonstrate that proteoglycan orientation also occurs after intermittent loading of both cortical and cancellous mammalian bonein vivo andin vitro. We also show that the change in birefringence is proportional to the magnitude of the applied strain, and that the reorientation occurs rapidly, reaching a maximal value after only 50 loading cycles. Examination of electron micrographs of bone tissue after staining with cupromeronic blue allows direct visualization and quantification of the change in proteoglycan orientation produced by loading. This shows that intermittent loading is associated with a realignment of the proteoglycan protein cores, bringing them some 5 degrees closer to the direction of collagen fibrils in the bone matrix.