Role of diurnal variation and receptor specificity in the opioidergic regulation of food intake in free-fed and food-deprived rats.

The effects of opioid agonists, morphine (MOR) and ketocyclazocine (KCZ), and antagonists, naltrexone (NALTX) and Mr2266, were investigated on food intake under various conditions, i.e., during light and dark phases of diurnal cycle and free-fed and fasting states in rats. NALTX showed a greater anorexic effect during dark phase, whereas Mr2266 produced such effect during light phase. This suggests that mu-receptors play a major role during dark phase while kappa-receptors are more important in light phase. The comparison of effects of different opioidergic drugs in fasted and free-fed rats showed that NALTX and Mr2266 reduced the elevated basal food intake in 18-h fasted rats to free-fed control levels. Therefore, it appears that enhanced endogenous mu- and kappa-directed neural mechanisms are one of the factors responsible for enhancing food intake in fasted rats. Differential role of MOR and KCZ on food intake in free-fed and fasted rats is also indicated in our study. Both agonists produced a biphasic response in fasted rats, i.e., hyperphagia (0-1 h) followed by hypophagia (1-6 h). However, a generalized hyperphagic effect is observed in free-fed rats (except during 3-6 h by MOR). The initial hyperphagic effect is more prominent in fasted rats which may be due to additive effects of endopioid mechanisms. Specificity of the response at various intervals is confirmed by blockade with NALTX and Mr2266. NALTX appears more potent than Mr2266 in antagonising the effects of MOR but markedly less potent than Mr2266 in inhibiting the effects of KCZ. This suggests that both MOR and KCZ have a mu as well as kappa component in food intake response.     

Virilism as a late manifestation in the Bardet-Biedl syndrome

The second case of virilism as a late manifestation of Bardet-Biedl syndrome (BBS) is described, with endocrine and histological evaluation. Both cases manifested ovulatory cycles and developed virilism in adulthood. Elevated plasma testosterone and 17-OH-progesterone were not suppressed by dexamethasone but were suppressed by medroxyprogesterone acetate. Peripheral and ovarian venous blood obtained at the time of surgery demonstrated a marked gradient for testosterone in both ovaries and for progesterone in the ovary bearing the corpus luteum. Histological evaluation of the ovaries demonstrated bilateral ovarian stromal hyperplasia with focal hyperthecosis. Bilateral ovariectomy resulted in complete correction of the endocrine abnormality, although the established hirsutism remains a mark of previous androgen excess.     

Distinct hemagglutinin and neuraminidase epitopes involved in antigenic variation of recent human parainfluenza virus type 2 isolates.

A panel of fourteen neutralizing anti-HN monoclonal antibodies (mAbs) to the prototype Greer strain of human parainfluenza virus type 2 (PI2) was used to determine the extent of antigenic variation in recent virus isolates. Competitive binding analysis with the mAbs indicated the presence of at least five distinct antigenic sites (I to V) on the HN glycoprotein molecule. MAbs recognizing different antigenic sites were found to be associated with the hemagglutinin (sites I, IV and V), hemagglutinin and neuraminidase (site II), or neuraminidase (site III) activities. The location of two distinct epitopes identifying the neuraminidase sites (II and III) was further verified from the generation of escape mutants. Antibodies directed to sites I and III failed to show any detectable binding or neutralizing activity against a number of natural PI2 virus isolates collected in Texas between 1986 and 1987. Interestingly, these natural variants, unlike the prototype virus, did not show any detectable neuraminidase activity with fetuin as a substrate and the enzyme activity was only detected with N-acetylneuramin-lactose as an alternative substrate. Despite the observed variation in the antigenic sites, primary infection with the prototype virus or the natural variants generated a protective immune response against challenge infection with the other virus strains.     

Effect of gossypol in association with chromium protoporphyrin on heme metabolic enzymes

Gossypol prevents the liberation of oxygen from oxyhemoglobin and exerts a hemolytic effect on erythrocytes. In excessive dosages of gossypol, an extreme burden is placed upon the respiratory and circulatory organs owing to the reduced oxygen carrying capacity of blood. Chromium protoporphyrin (CrPP) has been shown to either competitively suppress or to significantly ameliorate a variety of naturally occurring or experimentally induced forms of jaundice in animals and man. In this communication, a novel tissue dependent response to gossypol (50 micromol/kg bw) and gossypol in association with CrPP (50 micromol/kg bw) is described. Our results revealed that gossypol stimulated the hepatic, splenic, and renal delta-aminolevulinic acid synthase (ALA-S) activity, the heme biosynthetic enzyme, and simultaneous administration of CrPP and gossypol synergized the gossypol-mediated increase of ALA-S activity. Gossypol was found to be a potent stimulator of heme oxygenase (HMOX) activity in rat liver and kidney to varying degrees. This tissue response contrasted with that of the spleen, where gossypol decreased the activity of the enzyme. In consonance with the increased hepatic and renal HMOX activity, a marked increase was observed in total serum bilirubin concentration in gossypol treated rats. When rats were given CrPP simultaneously with gossypol, the gossypol mediated increase in hepatic and renal HMOX activity was effectively blocked. Furthermore, the increase in enzymatic activity was accomplished by a decline in the total microsomal protein content on gossypol administration. These findings emphasize the toxic effect of gossypol in eliciting increased heme degradation by stimulating HMOX activity in the liver and the kidney and the potential usefulness of CrPP in experimental and perhaps clinical conditions in which hyperbilirubinemia occurs.     

Mechanism of fluconazole resistance in Candida albicans biofilms: phase-specific role of efflux pumps and membrane sterols

Candida albicans biofilms are formed through three distinct developmental phases and are associated with high fluconazole (FLU) resistance. In the present study, we used a set of isogenic Candida strains lacking one or more of the drug efflux pumps Cdr1p, Cdr2p, and Mdr1p to determine their role in FLU resistance of biofilms. Additionally, variation in sterol profile as a possible mechanism of drug resistance was investigated. Our results indicate that parent and mutant strains formed similar biofilms. However, biofilms formed by double and triple mutants were more susceptible to FLU at 6 h (MIC = 64 and 16 microg/ml, respectively) than the wild-type strain (MIC > 256 microg/ml). At later time points (12 and 48 h), all the strains became resistant to this azole (MIC > or = 256 microg/ml), indicating lack of involvement of efflux pumps in resistance at late stages of biofilm formation. Northern blot analyses revealed that Candida biofilms expressed CDR and MDR1 genes in all the developmental phases, while planktonic cells expressed these genes only at the 12- and 48-h time points. Functionality of efflux pumps was assayed by rhodamine (Rh123) efflux assays, which revealed significant differences in Rh123 retention between biofilm and planktonic cells at the early phase (P = 0.0006) but not at later stages (12 and 48 h). Sterol analyses showed that ergosterol levels were significantly decreased (P < 0.001) at intermediate and mature phases, compared to those in early-phase biofilms. These studies suggest that multicomponent, phase-specific mechanisms are operative in antifungal resistance of fungal biofilms.     

Molecular cloning and sequence analysis of the fusion glycoprotein gene of human parainfluenza virus type 2

A cDNA clone containing a 2.0-kb insert was identified as the human parainfluenza virus type 2 (PI2) fusion glycoprotein gene by hybridizing with a viral RNA probe and a synthetic oligonucleotide derived from a conserved sequence found in other paramyxovirus fusion protein genes. The complete nucleotide sequence of the glycoprotein gene was determined by the dideoxynucleotide sequencing procedure and found to contain a single, large open reading frame encoding a protein of 551 amino acids with a calculated molecular weight of 59,664. Comparison of the P12 fusion protein with those of other paramyxoviruses indicated similarities in overall length, N-terminal signal peptide sequence (amino acids 7 to 25), C-terminal membrane-spanning region (amino acids 486 to 513), and a highly conserved fusion sequence region at the N-terminus of the F1 subunit (amino acids 107 to 132).     

Frequent deletions in nine newly immortal human cell lines.

Nine newly immortal lines of human fibroblasts transfected with SV40 T antigen were examined for recurrent chromosome losses. In order of decreasing frequency, all nine lines had three or more of the following minimal deletions specifically associated with the immortalization event: del(6)(q21), del(3)(p24), del(1)(p34), del(4)(p25), del(5)(p14), del(11)(p11), del(11)(q14), del(12)(p12), and del(14)(p?). Many other chromosome changes were not clearly associated with immortalization, but were acquired during other stages of this multistep model of neoplastic transformation. We propose that these chromosome loci associated with immortalization are candidates for the location of genes involved in cellular senescence.     

Biodegradation studies on periodate oxidized cellulose

Sodium periodate oxidized cellulose was found to degrade into small molecules when implanted subcutaneously in rats. Thus the potentiality of using oxidized cellulose as a biodegradable drug carrier is envisaged.