Molecular cloning and functional expression of the bumetanide-sensitive Na-K-Cl cotransporter.

By mediating the coupled movement of Na, K, and Cl ions across the plasma membrane of most animal cells, the bumetanide-sensitive Na-K-Cl cotransporter (NKCC) plays a vital role in the regulation of ionic balance and cell volume. The transporter is a central element in the process of vectorial salt transport in secretory and absorptive epithelia. A cDNA encoding a Na-K-Cl cotransport protein was isolated from a shark rectal gland library by screening with monoclonal antibodies to the native shark cotransporter. The 1191-residue protein predicted from the cDNA sequence has 12 putative transmembrane domains flanked by large cytoplasmic N and C termini. Regulatory phosphoacceptor residues in isolated peptides are identified as Thr-189 and Thr-1114 in the predicted sequence. Northern blot analysis identified a 7.4-kb mRNA in rectal gland and most other shark tissues; a 5.2-kb mRNA was restricted to shark kidney. Homology with an uncharacterized gene from Caenorhabditis elegans and with the thiazide-sensitive Na-Cl cotransporter of flounder urinary bladder was found over most of the coding region; shorter stretches of homology were found with a C. elegans cDNA and with an uncharacterized gene of cyanobacterium. Human HEK-293 cells have been stably transfected with the shark cDNA and shown to express Na-K-Cl cotransport activity with the bumetanide sensitivity of the shark protein. The expressed transporter is functionally quiescent in the host cells and can be activated by depleting the cells of chloride.     

Identification of the second chromophore of Escherichia coli and yeast DNA photolyases as 5,10-methenyltetrahydrofolate.

Denaturation of DNA photolyase (deoxyribodipyrimidine photolyase, EC 4.1.99.3) from Escherichia coli with guanidine hydrochloride or acidification to pH 2 released, in addition to FAD, a chromophore with the spectral and chromatographic properties of a reduced pterin. Treatment of the enzyme with iodine prior to acidification converted the chromophore to a stable, oxidized derivative, which was resolved by HPLC into four species with identical spectral properties. The same species, in the same distribution, were obtained from the yeast enzyme. The material isolated from the iodine-oxidized enzyme was shown to be a pterin by conversion to pterin-6-carboxylic acid with alkaline permanganate and was found to release glutamate upon acid hydrolysis. The presence of 10-formylfolate in the isolated, oxidized chromophore was demonstrated by absorption and fluorescence spectroscopy and by deformylation and conversion to folic acid. Analysis of the distribution of polyglutamates revealed that the four species identified by HPLC corresponded to the tri-, tetra-, penta-, and hexaglutamate derivatives of 10-formylfolate. The results were consistent with gamma linkages in the triglutamate derivative with additional glutamates linked via the alpha-carboxyl group of the preceding residue. Treatment with rat plasma hydrolase produced the monoglutamate derivative of 10-formylfolate. The native, enzyme-bound form of the folate cofactor was identified as 5,10-methenyltetrahydrofolylpolyglutamate by effecting release and isolation at low pH to protect the 5,10-methenyl bridge and preserve the reduced pyrazine ring structure.     

Drug-induced parkinsonism: a review

Summary— The main clinical features, pathophysiology and underlying mechanisms of drug-induced parkinsonism are reviewed. The clinical manifestations of drug-induced parkinsonism are often indistinguishable from idiopathic Parkinson's disease. However, some subtle differences may exist: for example drug-induced parkinsonism is often associated with tardive dyskinesias, bilateral symptoms and the absence of resting tremor, etc. Besides toxins ( eg manganese, carbon monoxide or MPTP), many drugs are known to produce parkinsonism: dopamine blocking drugs (true neuroleptics used as antipsychotics: phenothiazines, butyrophenones, thioxanthenes but also sulpiride, "hidden" neuroleptics prescribed as anti-nausea or anti-vomiting drugs (such as metoclopramide and other benzamide derivatives), dopamine depleting drugs (reserpine, tetrabenazine), alpha-methyldopa, calcium channel blockers (flunarizine, cinnari-zine, etc). The putative role of other drugs ( eg fluoxetine, lithium, amiodarone) as well as the therapeutic management of this side effect are reviewed.     

THE INFLUENCE OF OTHER DISEASES UPON THE OUTCOME OF COLORECTAL CANCER PATIENTS

Little attention may be paid during follow up of colorectal cancer patients to other medical problems because the follow up is normally focused upon the diagnosis of recurrence and the detection of metachronous neoplasms. Attention directed at improving the medical condition of patients would be justified if it were shown that other diseases had a significant effect upon survival. Review of a selected consecutive series of 207 patients included collection of data about variables relating to demography, pathology, presentation, smoking, present and past health, performance, surgery, complications, length of stay, mortality, follow up and cause of death. Significance of relationships between medical and surgical problems and the outcome was determined by analyses of variation. Medical problems were present in 79% of patients; correlated with advancing age. Medical problems were not associated with complications, or with inpatient death. Previous cerebrovascular accident. dementia, limited mobility and increasing numbers of problems were associated with prolonged stay. Prolongation of stay, however, was related mainly to surgical complications. Smoking, which was present in 50% of patients, did not alter performance status, stage or substage, stay or survival significantly. Smoking and respiratory complications were associated significantly. Patients with heart or peripheral vascular disease had significantly poorer survival (P= 0.07) than those without those problems. Survival was reduced significantly for patients known to have diabetes, cardiovascular and cerebrovascular disease and limited mobility. Other malignant neoplasms were responsible for 18% of deaths which were unrelated to colorectal cancer. Residual or recurrent colorectal cancer had a more rapid adverse influence upon outcome than did medical problems. Attention to preventative therapy of cardiovascular disease during follow up might improve survival of patients who have resections for colorectal carcinomata.     

Immune modification and complications of immunosuppression.

For transplant recipients, immunosuppression is necessary to prevent rejection. The type of immunosuppression varies according to the patient and institution; however, most patients receive double or triple drug regimens. Thus, thorough nursing assessment and intervention are essential throughout the transplant period. Research in this area continues, leading to a promising future for transplantation.     

Amplification of Thalamic Projections to Middle Suprasylvian Cortex following Ablation of Immature Primary Visual Cortex in the Cat

The purpose of the present study was to identify expansionsin thalamic projections to the middle suprasylvian (MS) cortexthat could be linked to the sparing of visually guided behaviorsthat follow the removal of visual cortex early in postnatallife. Injections of retrograde tracers were made into the medialbank of the middle suprasylvian sulcus in intact, adult catsand in adult cats that had incurred ablations of areas 17 and18 on the day of birth (P1), P28, or