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Cysteine string protein immunoreactivity in the nervous system and adrenal gland of rat.

Cysteine string proteins (csps) are a recently discovered class of cysteine-rich proteins. They have been shown to associate preferentially with synaptic vesicle fractions of Torpedo electric organ or rat brain where they have been implicated in events associated with transmitter secretion. However, to date there has been no information concerning the distribution of csps in rat tissues. We investigated the localization of csps in the rat retina and CNS using immunohistochemistry with affinity purified anti-csp antibodies. Specific csp immunoreactivity having a punctate appearance is present throughout the neuraxis. Csp immunoreactivity is particularly abundant in synapse-rich regions including those of the retina, main olfactory bulb, hippocampal formation, and cerebellum. White matter tracts are devoid of csp immunoreactivity. Neuromuscular junctions show strong csp immunoreactivity. This localization of csp immunoreactivity is compatible with a role for csps in presynaptic events at a wide variety of synapses. Immunohistochemical analysis of a non-neuronal, secretory tissue, the adrenal gland, reveals prominent csp immunoreactivity in the chromaffin cells of the adrenal medulla. However, csp immunoreactivity is not detected in adrenal cortical regions. These findings are confirmed and extended by immunoblot and Northern analyses which identify a 35 kDa and a 5 kb product, respectively, in extracts of adrenal. The presence of csps in the adrenal medulla suggests that these proteins may also participate in secretion-related events in certain non-neuronal cells.

Adrenal Glands↗

Paramedian insertion of Tenckhoff catheters with three purse-string sutures reduces the risk of leakage.

Starting peritoneal dialysis (PD) immediately after insertion of a peritoneal dialysis catheter is essential in some patients. However, due to a poor insertion technique, leakage may occur in up to 20% of patients after insertion of a peritoneal dialysis catheter, for example, in the midline. PD was started in 50 consecutive patients (age range 7-81 years). Under local anesthesia the Tenckhoff catheter was inserted about 3 cm lateral to the linea alba (mostly to the right) near the navel. The ventral and dorsal fasciae of the rectus muscle were split sagitally before entering the peritoneal membrane by a small incision. One purse-string suture fixed the peritoneal membrane around the inner cuff, while the second suture fixed the dorsal fascia of the rectus muscle around the outer side of the cuff. A third suture was placed around the catheter in the ventral fascia. Dialysis in all our patients was started peroperatively, initially by the use of 1 L of peritoneal dialysis fluid (Dianeal, Baxter Medical AB, Sweden). Bed rest for 2 or 3 days was requested of and performed by most patients. Only one early and no late leakages occurred. At reoperation of the patient with the leak, the second suture was found to have been loosened. The technique is easy to handle and enables immediate dialysis. The risk for leakage is very low.

Adolescent↗

Cysteine string proteins associated with secretory granules of the rat neurohypophysis.

The properties and subcellular distribution of cysteine string proteins (csps) were analyzed in peptidergic nerve terminals of the rat neurohypophysis. Polyclonal antibodies raised against recombinant rat brain csp recognized a 36 kDa protein in isolated neurosecretosomes from the post-pituitary. After chemical deacylation, a single 27 kDa form was detected that displayed identical properties to csps in a whole-brain synaptosomal fraction. Immunoisolation demonstrated that synaptophysin and csps were located in the same vesicles. Density gradient centrifugation of postsynaptosomal supernatants of neurohypophysial homogenates revealed that csps and VAMP were present in two distinct vesicle populations. Synaptophysin was only detected in the slowly migrating population corresponding to small synaptic vesicles, whereas arginine vasopressin was present in the more rapidly sedimenting population indicating that it contains large dense core vesicles (LDCVs). Immobilized antibodies against csp, synaptotagmin, or VAMP captured vesicular arginine vasopressin confirming the association of these proteins with LDCVs. Co-immunoprecipitation assays with proteins solubilized from neurohypophysial or whole-brain nerve terminals failed to reveal complexes containing csp and [125I]omegaGVIA receptors. These results indicate that csps in the CNS are associated with both small synaptic vesicles and LDCVs. However, they do not provide support for the hypothesis that protein complexes implicated in exocytosis, which interact with presynaptic N-type calcium channels, contain csps.

Animals↗

Evidence that cysteine string proteins regulate an early step in the Ca2+-dependent secretion of neurotransmitter at Drosophila neuromuscular junctions.

Previous work indicated that the temperature-dependent block of synaptic transmission in cysteine string protein (csp) mutants of Drosophila was attributable to a failure of nerve impulses to trigger transmitter release. The current investigations were undertaken to resolve in more detail the mechanism of this transmission deficit. Our studies reveal that the spider venom toxin alpha-latrotoxin can trigger a sustained discharge of quanta at neuromuscular junctions of csp mutant larvae at nonpermissive temperature. The same is true of the calcium ionophore ionomycin. However, solutions with an elevated concentration of K or Ca ions fail to circumvent the block of quantal secretion in these mutants. Likewise, 4-aminopyridine, which augments transmitter release at permissive temperature in csp mutants, fails to reverse the inhibition of impulse-evoked transmitter release at elevated temperature. These data are consistent with the hypothesis that there is a deficit either in Ca ion entry or in the ability of Ca ions to trigger exocytosis in csp mutants at nonpermissive temperatures. In part, because of previous work showing that csps are important for the functional expression of N-type Ca channels in frog oocytes, we favor the idea that csps participate in a regulatory interaction involving presynaptic Ca channels.

4-Aminopyridine↗

Cysteine string protein is required for calcium secretion coupling of evoked neurotransmission in drosophila but not for vesicle recycling.

The entire deletion of the cysteine string protein (CSP) gene causes a temperature-sensitive (ts) block of evoked neurotransmission in Drosophila. CSP has been found to interact in vitro with the clathrin-uncoating ATPase HSC70, suggesting a potential role of CSP in vesicle recycling. Using FM1-43 imaging, we analyzed whether the ts block of neurotransmission in csp mutants is caused by a defect in vesicle exocytosis or vesicle recycling. We determined that FM1-43-labeled synaptic boutons of csp mutant neuromuscular junctions fail to destain at 32 degrees C after K+ depolarization, and that FM1-43 dye uptake cannot be evoked by K+ stimulation at 32 degrees C. However, when we stimulated dye uptake independent of depolarization by using black widow spider venom (BWSV), we observed endocytotic uptake of FM1-43. This suggests that endocytosis exhibits no primary ts defect. In addition, we found no ts defect of vesicle recycling at 32 degrees C that would correlate with the ts block of neurotransmission. We also discovered that BWSV and the calcium ionophore calcimycin stimulate FM1-43 destaining and quantal release in csp mutants at 32 degrees C when depolarization fails to evoke any response. The wild-type-like, calcimycin-induced response in csp null mutants indicates that some aspect of the depolarization-dependent calcium signaling pathway must be impaired, either calcium entry, calcium action, or both. Collectively, our results indicate that the csp mutation affects calcium secretion coupling of evoked exocytosis but not vesicle recycling. This supports the hypothesis that CSP links synaptic vesicles to calcium secretion coupling.

Animals↗

Carotid string sign resulting from an aberrant branch of the internal carotid artery.

Branches of the extracranial internal carotid artery are very rare. A case is reported wherein an aberrant artery originated from the bulb of the internal carotid artery (ICA) approximately 2 cm from the bifurcation. The ICA was occluded distal to the branch's origin. Arteriography in this case gave the appearance of a carotid "string sign". Vascular surgeons and radiologists should be aware of this anomaly when interpreting carotid arteriograms.

Aged↗

Cardiopulmonary auscultation: duo for strings--Opus 99.

In spite of increasing mechanization in medicine and reliance on "high-tech" diagnostic tools, bedside clinical skills of the attending physician can still identify findings that are missed by the more sophisticated devices. Using a stethoscope, we relied on our skills in inspection, palpation, percussion, auscultation, as well as echocardiography and phonocardiography to diagnose a patient whose murmur was very reminiscent of the D-sharp pizzicato in the Cello Sonata in F, Opus 99, by Johannes Brahms. Initial echocardiography was not helpful. We suspected an anomalous chorda and confirmed this with phonocardiography and a second echocardiography. Although advances in cardiac imaging are extremely helpful, the use of simple clinical skills, in addition to being fun, is not obsolete. Cardiopulmonary auscultation should receive more emphasis in the medical school curriculum and clinical training.

Autopsy↗

String-plucking as a mechanism of chordal rupture during balloon mitral valvuloplasty using inoue balloon catheter.

Percutaneous transvenous mitral commissurotomy using the Inoue technique was performed in a 59-year-old female with mitral stenosis and a severely calcified mitral leaflets. Although not entrapped in the subvalvular apparatus, the balloon catheter was deviated away from the mitral orifice-apex axis of the left ventricle during the inflation of the proximal balloon, which plucked and severed the chordae tendineae of the posterior mitral leaflet and resulted in severe mitral regurgitation.

Calcinosis↗