Extracorporeal shock wave lithotripsy of gall stones: an in vitro comparison between an electrohydraulic and a piezoceramic device.

A comparative study of the effectiveness of two types of lithotripter in fragmenting gall bladder stones is reported. The machines used were a Piezolith 2300, which generates shock waves by the piezoceramic principle, and a Dornier MPL 9000, which produces the shock waves by underwater spark discharge. With each machine, corresponding stones of 45 pairs of weight and volume matched calculi (median volume 0.5 cm3, median diameter 10.5 mm) obtained at cholecystectomy were treated. All stones were successfully disintegrated (fragments smaller than 2 mm) with up to 5400 (median 628) shocks with the Piezolith and 3450 (median 428) shocks with the MPL 9000 lithotripters. With the Piezolith, operating at the highest power setting, a 1.65 fold median higher number of shocks was required for stone fragmentation than with the MPL 9000 at a medium power setting. Stone volume seemed to be the only determinant which affected ease of fragmentation; composition and density of the stones as assessed by computed tomography did not seem to be governing factors.     

Organization of dopamine D1 and D2 receptors in human striatum: receptor autoradiographic studies in Huntington's disease and schizophrenia

The technique of quantitative autoradiography was used to examine the effects of Huntington's disease (HD) and schizophrenia on the organization of striatal dopamine (DA) D1 and D2 receptors. Whereas the striatum of HD cases showed a reduction in the density of D1 ([3H]SCH 23390) and D2 ([3H]spiroperidol) receptors, the patterning of D2 receptor loss did not match that of the D1 receptor loss. The HD loss of D1 D1 receptors (65%) is far greater than the loss of D2 receptors (28%). Whereas there was a dorsal-ventral gradient of effect on both receptor subtypes, the effects of HD on D2 receptors in the ventral putamen (PUT) and nucleus accumben septi (NAS) were minimal. Similarly, muscarinic M1 and M2 receptors demonstrate different patterns of alteration in HD. The M2 subtype, labeled with [3H]N-methylscopolamine (in the presence of excess pirenzepine to occlude M1 sites), was depleted far more than the M1 receptor subtype, labeled with [3H]pirenzepine. Although the effects of HD on [3H]mazindol labeling of DA terminals were more heterogeneous, there appeared to be a relative preservation of this afferent input to the striatum of the HD cases. In the schizophrenic cases, our autoradiographic studies confirm previous reports of an elevation of D2 receptor density in the striata of many schizophrenics. This increase was evident even though two of the three cases were known to have not been treated with neuroleptics, and the third case may also have been drug naive. However, the increase was far greater in the NAS (164%) and ventral PUT (173%) than more dorsally in the striatum (68%). The density of D1 receptors and DA terminals labeled with [3H]mazindol in the striatum of schizophrenics was not significantly different from that of control cases. Thus in both HD and schizophrenia, the ratio of D2/D1 receptors is altered in favor of the D2 population, particularly in the NAS.     

Localisation and identification of melanocyte-stimulating hormones in the fish brain

The existence of melanocyte-stimulating hormone (MSH) in fish brains was investigated by a range of techniques: radioimmunoassay, HPLC, bioassay, and immunocytochemistry. Immunoreactive alpha MSH (ir alpha MSH) was detected by radioimmunoassay in all regions of carp and trout brains, with the highest concentration in the basal hypothalamus. In trout, ir alpha MSH cell bodies were located by immunocytochemistry only periventricularly, in the medial basal hypothalamus near the third ventricle, whereas in the carp ir alpha MSH staining was seen both in periventricular cells and also in some of the magnocellular neurones in the lateral hypothalamus. When white-adapted fish were transferred to a black tank for 6 days, the melanin-concentrating hormone (MCH) content of the basal hypothalamus of both carp and trout increased 2- and 4.6-fold, respectively, but the alpha MSH content did not change in either species. Analysis by HPLC of pituitary gland, hypothalamic, and optic tectal extracts revealed that the pituitary contains desacetyl, monoacetyl, and diacetyl alpha MSH, although the ratio of these forms differed in the two species. The hypothalamus and optic tectum, however, contained predominantly the desacetyl form of alpha MSH. Bioassays for MSH in the HPLC fractions revealed the existence of presumptive beta MSH in both the pituitary and hypothalamus. An argument is advanced that the periventricular ir alpha MSH neurones are homologous with the proopiomelanocortin cells of the arcuate nucleus in mammals, and that the immunocytochemical alpha MSH-like activity in the MCH neurones may not be authentic alpha MSH.     

Treatment of pigment epithelial detachments due to age-related macular degeneration with intra-ocular C3F8 injection*

Purpose: To flatten pigment epithelial detachments (PED) cue to age-related macular degeneration in an attempt to visualize the underlying choroidal neovascularization by fluorescein angiography (FA) and reveal a treatment target. Methods: Nine patients with PED received intravitreal gas injections via the pars plana and postured face down. Fluorescein angiograms were obtained before and after gas injection. In two patients, retinal scotopic sensitivity was also measured. Results: Eight patients demonstrated change in the shape and size of the PED following gas injection. Four patients showed a better delineation of underlying structures on FA. Three patients had focal laser treatment to the newly visible choroidal neovascular complex, but this was successful in only one patient with flattening of the PED. Conclusion: Pigment epithelial detachments can be modified by intravitreal gas injection in some patients, but this treatment did not have a major impact on overall outcome or management.     

An industrial hygiene methodology developed in support of a retrospective morbidity case-control study.

An industrial hygiene methodology that was developed in support of an epidemiologic case-control study is described. This study was conducted to investigate a potentially increased incidence of colorectal cancer among employees who worked at a unit that manufactured polypropylene by a heavy diluent process. Retrospective epidemiologic case-control studies typically have exposure assessment problems because industrial hygiene monitoring data are often not available. Misleading job titles are another problem that can provide a poor framework for estimating exposures. In addition, a job title-based exposure assessment assumes individual work patterns are not important in assessing worker exposures, although this is contradictory to industrial hygiene experience. The design of the case-control study provided an innovative industrial hygiene approach to circumvent these typical exposure estimating problems. The industrial hygiene methodology of the case-control study included assessing historical exposures, developing an exposure estimating matrix, selecting candidate etiologic agents based on a joint toxicologic and industrial hygiene review, administering a work activity questionnaire, calculating exposure scores, and conducting a statistical analysis. The study design also provided an additional exposure measurement independent of the toxicologic and industrial hygiene review. This provided an opportunity to compare the likelihood of exposure misclassification and, as expected, showed that a more detailed exposure estimate resulted in less misclassification.     

Long-term effect of acetazolamide in a patient with retinitis pigmentosa

The authors studied the therapeutic effect of acetazolamide on a patient with autosomal dominant retinitis pigmentosa complicated by retinal edema. In addition to reduction of macular edema and some improvement of central vision, they found an unexpected progressive increase in extrafoveal retinal sensitivity with prolonged medication. It is proposed that the therapeutic effect is mediated by alteration of retinal pigment epithelial function and that disturbed polarity is restored to a more normal state.