The Association of Organizational Justice with Job Satisfaction and Organizational Commitment among Nigerian Correctional Staff.

Correctional staff are a necessary and valuable resource for correctional institutions, in both Western and Nonwestern nations; however, studies of correctional staff in Nonwestern nations, particularly those in Africa, are lacking. Improving the job satisfaction and organizational commitment of these staff are imperative, as both of these job attitudes have been linked to many salient beneficial outcomes. Most of the existing empirical research on correctional staff organizational justice explores only the effects of procedural and distributive justice and ignores interpersonal justice. Additionally, there has been little research on how procedural, distributive, and interpersonal justice affect correctional staff in Nonwestern correctional organizations. The current study explored the effects of all three forms of organizational justice on the job satisfaction and organizational commitment of staff at a medium security prison in southeast Nigeria. Based on Ordinary Least Squares (OLS) regression, all three forms of justice had significant positive effects on commitment. Procedural and interpersonal justice had positive effects on job satisfaction, while distributive justice had nonsignificant effects. Correctional administrators need to be aware the importance of procedural, distributive, and interpersonal justice and attempt to improve perceptions of these organizational justice variables.

Clustered folate receptors deliver 5-methyltetrahydrofolate to cytoplasm of MA104 cells.

Previously, a high affinity, glycosylphosphatidylinositol-anchored receptor for folate and a caveolae internalization cycle have been found necessary for potocytosis of 5-methyltetrahydrofolate in MA104. We now show by cell fractionation that folate receptors also must be clustered in caveolae for potocytosis. An enriched fraction of caveolae from control cells retained 65-70% of the [3H]folic acid bound to cells in culture. Exposure of cells to the cholesterol-binding drug, filipin, which is known to uncluster receptors, shifted approximately 50% of the bound [3H]folic acid from the caveolae fraction to the noncaveolae membrane fraction and markedly inhibited internalization of [3H]folic acid. An mAb directed against the folate receptor also shifted approximately 50% of the caveolae-associated [3H]folic acid to noncaveolae membrane, indicating the antibody perturbs the normal receptor distribution. Concordantly, the mAb inhibited the delivery of 5-methyl[3H]tetrahydrofolate to the cytoplasm. Receptor bound 5-methyl[3H]tetrahydrofolate moved directly from caveolae to the cytoplasm and was not blocked by phenylarsine oxide, an inhibitor of receptor-mediated endocytosis. These results suggest cell fractionation can be used to study the uptake of molecules by caveolae.

Hormonal regulation of caveolae internalization.

Caveolae undergo a cyclic transition from a flat segment of membrane to a vesicle that then returns to the cell surface. Here we present evidence that this cycle depends on a population of protein kinase C-alpha (PKC-alpha) molecules that reside in the caveolae membrane where they phosphorylate a 90-kD protein. This cycle can be interrupted by treatment of the cells with phorbol-12,13-dibutyrate or agents that raise the concentration of diacylglycerol in the cell. Each of these conditions displaces PKC-alpha from caveolae, inhibits the phosphorylation of the 90-kD protein, and prevents internalization. Caveolae also contain a protein phosphatase that dephosphorylates the 90-kD once PKC-alpha is gone. A similar dissociation of PKC-alpha from caveolae and inhibition of invagination was observed when cells were treated with histamine. This effect was blocked by pyrilamine but not cimetidine, indicating the involvement of histamine H1 receptors. These findings suggest that the caveolae internalization cycle is hormonally regulated.

Caveolin moves from caveolae to the Golgi apparatus in response to cholesterol oxidation.

Caveolae are a membrane specialization used to internalize molecules by potocytosis. Caveolin, an integral membrane protein, is associated with the striated coat present on the cytoplasmic surface of the caveolae membrane. We now report that oxidation of caveolar cholesterol with cholesterol oxidase rapidly displaces the caveolin from the plasma membrane to intracellular vesicles that colocalize with Golgi apparatus markers. After the enzyme is removed from the medium, caveolin returns to caveolae. When untreated cells are gently homogenized, caveolin on the plasma membrane is accessible to both anti-caveolin IgG and trypsin. After cholesterol oxidase treatment, however, Golgi-associated caveolin is inaccessible to both of these molecules. Brefeldin A, which inhibits ER to Golgi trafficking, blocks the appearance of caveolin in the Golgi apparatus but does not prevent caveolin from leaving the plasma membrane. Indirect immunogold localization experiments show that in the presence of cholesterol oxidase caveolin leaves the plasma membrane and becomes associated with endoplasmic reticulum and Golgi compartments. Surprisingly, the loss of caveolin from the plasma membrane does not affect the number or morphology of the caveolae.

Caveolin cycles between plasma membrane caveolae and the Golgi complex by microtubule-dependent and microtubule-independent steps.

Caveolin is a protein associated with the characteristic coats that decorate the cytoplasmic face of plasma membrane caveolae. Recently it was found that exposure of human fibroblasts to cholesterol oxidase (CO) rapidly induces caveolin to redistribute to the ER and then to the Golgi complex, and that subsequent removal of CO allows caveolin to return to the plasma membrane (Smart, E. J., Y.-S. Ying, P. A. Conrad, R. G. W. Anderson, J. Cell Biol. 1994, 127:1185-1197). We now present evidence that caveolin normally undergoes microtubule-dependent cycling between the plasma membrane and the Golgi. In cells that were treated briefly with nocodazole and then with a mixture of nocodazole plus CO, caveolin relocated from the plasma membrane to the ER and then to the ER/Golgi intermediate compartment (ERGIC), but subsequent movement to the Golgi was not observed. Even in the absence of CO, nocodazole caused caveolin to accumulate in the ERGIC. Nocodazole did not retard the movement of caveolin from the Golgi to the plasma membrane after removal of CO. Incubation of cells at 15 degrees followed by elevation of the temperature to 37 degrees caused caveolin to accumulate first in the ERGIC and then in the Golgi, before finally reestablishing its normal steady state distribution predominantly in plasma membrane caveolae. In cells released from a 15 degrees block, movement of caveolin from the Golgi to the plasma membrane was not inhibited by nocodazole. Taken together, these results imply that caveolin cycles constitutively between the plasma membrane and the Golgi by a multi-step process, one of which, ERGIC-to-Golgi transport, requires microtubules. This novel, bidirectional pathway may indicate roles for microtubules in the maintenance of caveolae, and for caveolin in shuttling fatty acids and cholesterol between the plasma membrane and the ER/Golgi system.

Protein kinase C activators inhibit receptor-mediated potocytosis by preventing internalization of caveolae.

Potocytosis is an endocytic pathway that utilizes glycosylphosphatidylinositol-anchored membrane proteins and caveolae to concentrate and internalize small molecules. We now report that activators of protein kinase C are potent inhibitors of potocytosis. Activators such as phorbol-12-myristate-13-acetate (PMA) inhibit the internalization of receptors for 5-methyltetrahydrofolate but allow the internal receptor pool to return to the cell surface. PMA does not affect the clustering of the folate receptor but instead markedly reduces the number of caveolae. Exposure to PMA totally blocks the intracellular accumulation of 5-methyltetrahydrofolate without affecting receptor-independent uptake or the formation of polyglutamylated species of 5-methyltetrahydrofolate in the cytoplasm. These data suggest that PMA inhibits uptake by inactivating caveolae internalization.

Isolation and characterization of a Chlamydomonas reinhardtii mutant lacking the gamma-subunit of chloroplast coupling factor 1 (CF1).

Several nonphotoautotrophic mutants of Chlamydomonas reinhardtii were generated by transforming strain nit1-305 (cw 15) with exogenous DNA. An enrichment for potential photophosphorylation mutants was performed on medium containing arsenate, and acetate-requiring auxotrophs were then identified by replica plating. Strains containing a potential mutation in the nuclear DNA encoding the chloroplast coupling factor 1 (CF1) gamma-subunit (the atpC gene) were first identified serologically with a monospecific antiserum directed against the CF1 gamma-subunit polypeptide. Of several mutants isolated, one, designated T1-54, was characterized at the protein, DNA, and RNA levels. Mutant strain T1-54 lacks anti-CF1 gamma-subunit cross-reacting material, exhibits polymorphism at the atpC locus compared with the parental strain, and lacks the mRNA transcript for the CF1 gamma-subunit. The data are consistent with there being an insertion of exogenous DNA, a deletion of DNA, or both at the 5' end of the gene encoding the CF1 gamma-subunit.

Macrophage scavenger receptors and foam cell formation.

Scavenger receptors bind and internalize modified low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Because the expression of scavenger receptors is not down-regulated by cholesterol, macrophages (Mphi) expressing scavenger receptors can internalize substantial quantities of cholesteryl ester from oxidized LDL and HDL, leading to foam cell formation. Mphi express several different classes of the growing scavenger receptor family on their cell surface and their relative contribution to Mphi cholesterol physiology and atherogenesis is the subject of intense investigation. We focus on the potential role of two scavenger receptors, macrosialin and SR-BI/II in Mphi cholesterol metabolism. Macrosialin is a predominantly Mphi-specific oxidized LDL-binding protein and an atherogenic diet markedly up-regulates its hepatic expression in atherosclerosis-susceptible and atherosclerosis-resistant mouse strains. The HDL receptor, SR-BI and its splicing variant SR-BII, colocalize with caveolin in caveolae in Mphi. Caveolae are initial acceptor sites for cholesteryl esters and these findings indicate a possible role for caveolae and SR-BI in Mphi-selective lipid uptake and in regulating Mphi cholesterol flux in the vascular wall.

Cardiac myocyte adenosine receptors and caveolae.

The purine nucleoside adenosine exerts numerous effects in the mammalian heart, the most well-recognized being regulation of coronary blood flow and cardiac conduction. These effects are mediated via activation of G protein linked adenosine receptor subtypes, A(2a) and A(1) receptors, located primarily on vascular cells and cardiac myocytes, respectively. Although adenosine A(1) receptors are also expressed in ventricular myocytes, adenosine exerts no significant direct effects in these cells. A recent report from our laboratory indicates that ventricular myocyte A(1) receptors are concentrated in caveolin enriched plasma membrane microdomains referred to as caveolae. This review focuses on these recent findings and their relevance to subcellular compartmentalization of A(1) receptor signaling in ventricular myocardium.

Influence of caveolin, cholesterol, and lipoproteins on nitric oxide synthase: implications for vascular disease.

Caveolin-1 traffics cholesterol between the endoplasmic reticulum and cell surface caveolae in a non-vesicle chaperone complex which contains heat shock protein 56, cyclophilin 40, and cyclophilin A. Recent studies demonstrate that endothelial nitric oxide synthase (eNOS), caveolin, hetero-trimeric G-protein coupled receptors, and a calcium channel form an activation complex that is associated with cholesterol-rich caveolae. Oxidized LDL depletes caveolae of cholesterol and prevents agonist stimulation of eNOS by disrupting the activation complex. HDL antagonizes the effects of oxLDL by donating cholesterol to caveolae, thereby preserving the structure and function of caveolae. These findings and others provide a possible mechanistic basis for some of the molecular changes observed in vascular disease.

Class B scavenger receptors, caveolae and cholesterol homeostasis.

Class B scavenger receptors are predominantly localized to cholesterol and sphingomyelin-enriched domains within the plasma membrane, called caveolae. Caveolae and their associated protein, caveolin, have been implicated in cholesterol trafficking and in the regulation of cellular cholesterol homeostasis. Recent studies indicate that scavenger receptor, class B, type I (SR-BI) mediates cholesterol flux between cells and lipoproteins. Caveolae appear to be the sites within the plasma membrane where such exchange occurs, suggesting that the regulation of caveolae and caveolins may be pivotal to the net flux of cholesterol between cells and lipoproteins when they are bound to SR-BI.

The role of caveolae and caveolin in vesicle-dependent and vesicle-independent trafficking.

Caveolae can mediate endocytosis, transcytosis, and potocytosis. Our understanding of these processes as well as the elucidation of the molecular machinery involved has greatly expanded. In addition, caveolin, a 22 kDa protein often associated with caveolae, can promote the trafficking of sterol through the cytoplasm independent of vesicles. Caveolin also influences the formation, morphology, and function of caveolae. The ability of caveolae and caveolin to mediate macromolecular transport directly impacts a variety of physiological and pathophysiological processes.

Mercury vapour levels in a domestic environment following breakage of a clinical thermometer.

Following the breakage of a clinical thermometer in the kitchen of the author's own home, mercury vapour was found to be present in most rooms, but not in concentrations which exceeded the current threshold limit value (TLV). However, assuming a more stringent standard of safety, based on continuous exposure to mercury vapour, it was noted that some of the readings could be considered to be excessive, although these were of a freakish and transient nature. In reality the overall time-weighted average exposure of the occupants was within reasonable limits. Lack of ventilation was a major factor in maintaining discernible levels of vapour over a 3-week period. However, the advent of mild weather was instrumental in dispersing the vapour, by allowing the opening of windows. The residual mercury on the floors would seem to have evaporated, so that no long-term health risk ensued. Cross contamination of the hallway carpet was noted indicating that mercury had been transported on the soles of feet and shoes.

Specificity C and e: tests using Rh variant cells.

Monoclonal antibodies, specificity C, e, and Rh subgroup? ein the Section 1-Rh were tested with selected blood samples of various Rh variant types in KwaZulu-Natal, South Africa. The standard red cell serological techniques supplied were used.

Studies on section 2D1 monoclonal antibodies.

Monoclonal antibodies in "Other Blood Groups" were tested with random blood samples collected from the various ethnic groups in KwaZulu-Natal, South Africa, and with samples of selected red cell phenotypes. Standard red cell serological techniques were used.

Studies on section 2D3 monoclonal antibodies.

Monoclonal antibodies (MAbs) directed against CD-related antigens were tested with various red cell samples from different ethnic groups in KwaZulu-Natal. The MAbs were tested by standard red cell serological techniques. The MAbs with specificities CD44, CD58 and RBC, reacted with all the samples tested. CD99 was non-reactive. The two Rh?related MAbs showed possible Rh specificity by saline technique, as did one CD47, MAb 2D3-6.

The role of closed circuit television in the teaching of operative dentistry.

Closed circuit television has been used in the Department of Operative Dental Surgery of the University of Newcastle-upon-Tyne since 1966. The medium has played an increasingly important role in the teaching of technique courses, especially after 1978 when the large 80-place teaching laboratory of the newly-built Dental School was commissioned.

Resolution of lichen planus following removal of amalgam restorations in patients with proven allergy to mercury salts: a pilot study.

Thirteen patients with symptomatic oral lichen planus had been shown by patch testing to be allergic to ammoniated mercuric chloride. Replacement of amalgam restorations in these patients effected an improvement in all but one case. In some cases the resolution of symptoms was dramatic following the replacement of one or two fillings. The authors feel that the removal of all amalgam fillings need not be necessary except in the most intractable case.