Molecular and cellular responses of islets during perturbations of glucose homeostasis determined by in situ hybridization histochemistry

We have evaluated in situ hybridization histochemistry as a means of estimating simultaneously the level of prohormone mRNA and the dimensions of rat pancreatic islets. Localization of the 27-mer 32P-labeled oligonucleotide probes for rat proinsulin I, glucagon, and prosomatostatin I corresponded with localization of antibodies to the three hormones. In normal rats subjected to chronic hyperglycemic clamping, the density of the proinsulin mRNA signal increased 54%, islet size and number increased approximately 100%, while proglucagon mRNA signal was reduced 81%. Resection of 50% of the pancreas increased proinsulin mRNA 36% and proglucagon mRNA 500%; islet area doubled and islet number increased 50%. In 150-day-old diabetic ob/ob mice, there was an 18-fold expansion in islet area, a 4-fold increase in islet number, but no increase in insulin gene expression. In insulin-dependent streptozotocin-treated diabetic rats, islet area and number were profoundly reduced; insulin deprivation failed to raise proinsulin mRNA in surviving beta cells above control levels. Proglucagon mRNA was high despite the hyperglycemia but was reduced by insulin within 1 hr, suggesting that insulin regulates glucagon gene expression or is required for its regulation by glucose. In situ hybridization of rat islets provides a valid semiquantitative index of insulin and glucagon biosynthesis and of islet dimensions and reveals that normal but not diabetic islets meet increased insulin demand by increasing both number and biosynthetic activity of beta cells.

[Research on the dose-response relationship of hand transmitted vibration and its hygienic standard]

According to ISO 5349-1986, the akw(4) was 9.04-41.47m/s2 which was measured and calculated in 5 types of instruments: chain saw, cleaner, rock driller, riveter & emery wheel. There were 170 cases with white finger through epidemiologic investigation on 5 types of workers in 1,675 persons. Based on the work mentioned above, a formula, which represented worker cumulative exposure to vibration was deduced: D = [(a2kw(4).T)1/2.Y.d]2 Furthermore, the dose-response relationship of hand transmitted vibration and prevalence of white finger was computed, the regression equation was: P = 1.0904X - 6.214 2 Under precondition of exposure to vibration for 20 years with 90% of workers having no white fingers, the limit of hygienic standard of hand transmitted vibration in china should be set at 4 hours and as akw(4) less than or equal to 5 m/s2 based on the regression equation.

[The effect of biphenyl dimethyl dicarboxylate (DDB) on the fluidity of human erythrocyte membrane]

This paper deals with the effects of DDB on human RBC membrane fluidity as reflected by changes in the phase transition temperature and microviscosity monitored by ANS, NPN and DPH. The results showed that DDB decreased the fluidity of the shallow layer (ANS as probe), but increased the fluidity of the middle layer (NPN as probe) and deeper layer (DPH as probe). In addition, the drug was found to inhibit the hemolysis induced by MDA.

SecA protein is required for secretory protein translocation into E. coli membrane vesicles

The soluble and membrane components of an E. coli in vitro protein translocation system prepared from a secA amber mutant, secA13[Am], contain reduced levels of SecA and are markedly defective in both the cotranslational and posttranslational translocation of OmpA and alkaline phosphatase into membrane vesicles. Moreover, the removal of SecA from soluble components prepared from a wild-type strain by passage through an anti-SecA antibody column similarly abolishes protein translocation. Translocation activity is completely restored by addition of submicrogram amounts of purified SecA protein, implying that the observed defects are solely related to loss of SecA function. Interestingly, the translocation defect can be overcome by reconstitution of SecA into SecA-depleted membranes, suggesting that SecA is an essential, membrane-associated translocation factor.

Recombinant interferon-beta 2 (interleukin-6) induces myeloid differentiation

Human IFN-beta 2 cytokine produced in E. coli was purified to homogeneity by immunoaffinity and ion-exchange chromatography. The cytokine inhibits the growth of myeloleukemic M1 cells and induces their morphological and functional differentiation into macrophages. Differentiation was also observed in the histiocytic lymphoma U937 cells. The effect on U937 was synergized by IFN-gamma and under these conditions IFN-beta 2 produced the induction of (2'-5') oligo(A) synthetase typical to IFN action and to differentiation.

Growth inhibition of human breast carcinoma and leukemia/lymphoma cell lines by recombinant interferon-beta 2

Recombinant human interferon-beta 2 was produced in Escherichia coli by direct expression of cDNA encoding the mature protein sequence. At concentrations that stimulate DNA synthesis and growth in B-cell hybridomas and plasmacytomas, the cytokine was found to exert a strong inhibition on the growth of a number of carcinoma and leukemia/lymphoma cell lines. This antigrowth effect was observed in clonogenic assays and by measurements of cell number and thymidine incorporation in growing cultures. The effect was blocked by antibodies to a synthetic peptide from the N terminus of the molecule. Normal diploid fibroblasts were inhibited at concentrations higher than those needed for breast carcinoma cells.

Dimerization of the tat protein from human immunodeficiency virus: a cysteine-rich peptide mimics the normal metal-linked dimer interface

We have synthesized an 18-amino acid peptide that contains the cysteine-rich region of the tat protein from human immunodeficiency virus. Previous experiments in vitro with the intact tat protein have shown that these cysteines serve as metal ligands, causing tat to form metal-linked dimers. Ultraviolet absorption spectra show that the synthetic peptide (tat21-38) binds two Cd2+ or two Zn2+ ions per peptide monomer, and some changes in the circular dichroism spectra are seen as the metals bind. The peptide-metal complexes are completely resistant to proteolytic digestion, and mass spectrometry demonstrates that this peptide forms metal-linked dimers. The peptide can also combine with the intact tat protein to form metal-linked heterodimers. If these heterodimers are unable to trans-activate viral transcription, tat21-38 could be a lead compound for designing drugs to treat acquired immunodeficiency syndrome.

The effect of pleural pressure on the hypoxic pulmonary vasoconstrictor response in closed chest dogs

The effect of intrapleural pressure on the hypoxic pulmonary vasoconstrictor (HPV) responses to atelectasis and hypoxia were measured in two groups of anesthetized closed chest dogs. The right lung was continuously ventilated with 100% O2. The left lung was initially ventilated with 100% O2 (hyperoxia) but subsequently underwent either reabsorption atelectasis (atelectasis; group I) or ventilation with a hypoxic gas mixture (hypoxia; group II). The mean intrapleural pressure in the left hemithorax was 5.4 cm H2O during hyperoxia, but with left lung atelectasis decreased significantly to -3.8 cm H2O by 15 minutes and to -4.2 cm H2O by 90 minutes. Venous admixture (% VA) increased significantly from 10.3% during hyperoxia to 33.2% at 15 minutes of left lung atelectasis and to 34.6% at 90 minutes. However, after sternotomy with the left lung still atelectatic, the %VA decreased significantly to 25.4% For the hypoxia group, %VA increased significantly from 9.2% during hyperoxia to 29.9% at 15 minutes of left lung hypoxia and 25.1% at 90 minutes. HPV diverted blood flow away from both atelectatic lung and hypoxic lung. However, due to the negative intrapleural pressure generated during left lung resorption atelectasis when the chest was closed, HPV was less effective during atelectasis than during hypoxia.

Intravenous PGF2 alpha infusion does not enhance hypoxic pulmonary vasoconstriction during canine one-lung hypoxia

The effect of prostaglandin F2 alpha (PGF2 alpha) on the hypoxic pulmonary vasoconstrictor (HPV) response was studied in 12 closed-chest dogs anesthetized with pentobarbital and paralyzed with pancuronium. The right lung was ventilated continuously with 100% O2, while the left lung was either ventilated with 100% O2 ("hyperoxia") or ventilated with an hypoxic gas mixture ("hypoxia:" end-tidal PO2 approximately equal to 50.0 +/- 0.1 mmHg). Cardiac output (CO) was altered from a "normal" value of 2.89 +/- 0.26 1.min-1 to a "high" value of 3.55 +/- 0.26 1.min-1 by opening arteriovenous fistulae which allowed measurements of two points along a pressure-flow line. These four phases of left lung hypoxia or hyperoxia with normal and high cardiac output were performed in the absence of, and in the presence of, PGF2 alpha administered as a constant peripheral intravenous infusion of 1.0 microgram.kg-1.min-1. During left lung hypoxia, mean pulmonary artery pressure (PAP) increased significantly when compared to hyperoxia. With PGF2 alpha administration, mean PAP increased significantly during both hyperoxia and hypoxia. The presence or absence of PGF2 alpha had no effect on cardiac output or PaO2 during hypoxia. Relative blood flow to each lung was measured with a differential CO2 excretion (VCO2) method corrected for the Haldane effect. With both lungs hyperoxic, the percent left lung blood flow (%QL-VCO2) was 45 +/- 1%. When the left lung was exposed to hypoxia, the %QL-VCO2 decreased significantly to 29 +/- 3%. However, with the administration of PGF2 alpha, the %QL-VCO2 during left lung hypoxia did not change significantly 26 +/- 3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Rearrangements of chicken immunoglobulin genes in lymphoid cells transformed by the avian retroviral oncogene v-rel

The retroviral oncogene v-rel transforms poorly characterized lymphoid cells. We have explored the nature of these cells by analyzing the configuration and expression of immunoglobulin genes in chicken hemopoietic cells transformed by v-rel. None of the transformed cells expressed their immunoglobulin genes. The cells fell into three classes: class I cells have their immunoglobulin genes potentially in an embryonic configuration; class II and class III cells have lost one copy of the lambda light chain locus and have one copy of the heavy chain locus rearranged into a configuration that differs from what is found in mature B cells. In class II cells, the other heavy chain locus may be in embryonic configuration, whereas it is deleted in class III cells. The first of these classes may represent the earliest stage of the lymphoid lineage yet encountered among virus-transformed cells, whereas the second and third classes represent an apparently anomalous rearrangement whose origin remains unknown.

Interferon-gamma synergizes with tumor necrosis factor and with interleukin 1 and requires the presence of both monokines to induce antitumor cytotoxic activity in macrophages

Small concentrations of recombinant murine interferon-gamma (MuIFN-gamma), recombinant human interleukin 1 (HuIL-1), and recombinant murine tumor necrosis factor (MuTNF), added separately to cultures of thioglycolate-elicited peritoneal macrophages, produced no cytotoxic activity against L5178Y cells, a tumor cell line which is resistant to the direct toxic effects of these cytokines, either alone or in combination. However, small concentrations of MuIFN-gamma when combined with small concentrations of either HuIL-1 or MuTNF activated these macrophages to produce cytotoxic effects against L5178Y cells; small concentrations of HuIL-1 and MuTNF in combination had no macrophage activating activity. Specific antibody to MuTNF blocked the macrophage-activating synergistic effects of MuIFN-gamma + HuIL-1, and specific antibody to HuIL-1 blocked the macrophage-activating activity of MuIFN-gamma + MuTNF, indicating that MuTNF was induced in macrophage cultures treated with MuIFN-gamma + HuIL-1, and that murine IL-1 was induced in macrophage cultures treated with MuIFN-gamma + MuTNF. These results indicate that all three cytokines are required for induction of antitumor cytotoxic activation of macrophages. Experiments with a concentration of MuIFN-gamma which alone could activate macrophages revealed that both MuTNF and murine IL-1 were required for this activation. The demonstration that small concentrations of these three cytokines can act synergistically, but not separately, to activate macrophages indicates the importance of cytokine combinations in immunoregulation and in anti-tumor cell-mediated immune responses.

Interferon-gamma synergizes with tumor necrosis factor and with interleukin 1 and requires the presence of both monokines to induce antitumor cytotoxic activity in macrophages

Small concentrations of recombinant murine interferon-gamma (MuIFN-gamma), recombinant human interleukin 1 (HuIL-1), and recombinant murine tumor necrosis factor (MuTNF), added separately to cultures of thioglycolate-elicited peritoneal macrophages, produced no cytotoxic activity against L5178Y cells, a tumor cell line which is resistant to the direct toxic effects of these cytokines, either alone or in combination. However, small concentrations of MuIFN-gamma when combined with small concentrations of either HuIL-1 or MuTNF activated these macrophages to produce cytotoxic effects against L5178Y cells; small concentrations of HuIL-1 and MuTNF in combination had no macrophage activating activity. Specific antibody to MuTNF blocked the macrophage-activating synergistic effects of MuIFN-gamma + HuIL-1, and specific antibody to HuIL-1 blocked the macrophage-activating activity of MuIFN-gamma + MuTNF, indicating that MuTNF was induced in macrophage cultures treated with MuIFN-gamma + HuIL-1, and that murine IL-1 was induced in macrophage cultures treated with MuIFN-gamma + MuTNF. These results indicate that all three cytokines are required for induction of antitumor cytotoxic activation of macrophages. Experiments with a concentration of MuIFN-gamma which alone could activate macrophages revealed that both MuTNF and murine IL-1 were required for this activation. The demonstration that small concentrations of these three cytokines can act synergistically, but not separately, to activate macrophages indicates the importance of cytokine combinations in immunoregulation and in anti-tumor cell-mediated immune responses.

Measurement of plasminogen activator activity from human fibrosarcoma cells by a new microassay

Elevated levels of plasminogen activator (PA) activity have been correlated with neoplasia and may have an important role in tumor-cell invasion and metastasis. We have developed a new caseinolytic assay that uses an immunochemical approach to measure the activity of PA elaborated by malignant tumor cells. The highly sensitive assay consists in incubating a source of PA (viable tumor cells, cell extracts, or conditioned medium) with purified plasminogen in microtiter plates precoated with a suitable protein substrate such as casein. Clearance of the immobilized protein substrate by PA-generated plasmin is then measured by a technique based on the enzyme-linked immunosorbent assay. In experiments using urokinase as a source of PA, the assay displayed near linearity over several log units of urokinase activity and could detect as little as 10(-2) Ploug units of PA activity. Besides successfully measuring PA activity produced by the human HT 1080 fibrosarcoma cell line, the assay permitted detection of significant plasminogen-independent proteolytic activity generated by intact tumor cells cultured in direct contact with immobilized protein substrates.

High-dose almitrine bismesylate inhibits hypoxic pulmonary vasoconstriction in closed-chest dogs

The effect of almitrine bismesylate on the hypoxic pulmonary vasoconstrictor (HPV) response was studied in seven closed-chest dogs anesthetized with pentobarbital and paralyzed with pancuronium. The right lung was ventilated continuously with 100% O2, while the left lung was ventilated with either 100% O2 ("hyperoxia") or with an hypoxic gas mixture ("hypoxia": end-tidal PO2 = 50.1 +/- 0.1 mmHg). Cardiac output (CO) was altered from a "normal" value of 3.10 +/- 0.18 l . min-1 to a "high" value of 3.92 +/- 0.16 l . min-1 by opening arteriovenous fistulae which allowed measurements of two points along a pressure-flow line. These four phases of left lung hypoxia or hyperoxia with normal and high cardiac output were repeated in the presence and absence of almitrine. Almitrine bismesylate was administered as a constant infusion of 14.3 micrograms . kg-1 . min-1 for a mean plasma concentration of 219.5 +/- 26.4 ng . ml-1. Relative blood flow to each lung was measured with a differential CO2 excretion (VCO2) method corrected for the Haldane effect. With both lungs hyperoxic, the percent left lung blood flow (%QL-VCO2) was 44 +/- 1%. When the left lung was exposed to hypoxia, the %QL-VCO2 decreased significantly to 22 +/- 1%. However, with the administration of almitrine, the %QL-VCO2 during left lung hypoxia increased significantly to 36 +/- 2%. The arterial oxygen tension decreased significantly between hyperoxia (PaO2 = 633 +/- 6 mmHg) and hypoxia (271 +/- 31 mmHg). With the addition of almitrine, there was no change during hyperoxia; however, during hypoxia, the PaO2 decreased significantly to 124 +/- 15 mmHg. Cardiac output did not influence these findings. The pulmonary vascular conductance (G) is the slope of the pressure-flow line.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of antibiotics and other inhibitors on ATP-dependent protein translocation into membrane vesicles

The effects of several membrane antibiotics and other agents on ATP-dependent protein translocation were examined in membrane vesicles under conditions where no significant proton motive force was present. The membrane perturbants ethanol and procaine abolished ATP-dependent protein translocation. Phenethyl alcohol at low concentrations abolished translocation, whereas at high concentrations it allowed precursors to be translocated but inhibited their processing. Translocation of precursors promoted by phenethyl alcohol was temperature dependent and occurred without an added energy source but was enhanced by ATP. However, such precursors could not be further processed to mature forms upon removal of the alcohol. The membrane-active antibiotics polymyxin B and gramicidin S were strong inhibitors of translocation, whereas gramicidin D, cerulenin, and mycobacillin had no effect even at higher concentrations, indicating some specificity in interference with protein translocation. Duramycin, an antibiotic previously shown to affect protein-lipid interaction, severely impaired protein translocation. These results showed that membrane structures play important roles, either directly or indirectly, in protein translocation. Chelating agents 1,10-phenanthroline and EDTA, but not EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid], also abolished protein translocation.

Spontaneous and induced interferon production by peripheral blood leucocytes from control population and patients with herpes genitalis

The spontaneous and PHA induced levels of interferon were measured in peripheral blood leucocyte cultures of twenty-eight individuals diagnosed as positive for herpes genitalis, and in a group of control subjects. As reported by Cunningham and Merigan [1983] for herpes labialis, leucocytes from individuals with herpes genitalis produced low levels of interferon spontaneously; however, similar results were found for individuals within the control population. No statistically significant difference could be found for PHA induced interferon levels, antigen induced interferon levels, or helper/suppressor cell ratios between the herpes genitalis population and control population. Our results indicate that interferon does not play a major role in the latency or recurrence of herpes genitalis.

A training model for the stereomicroscopic evaluation of flap survival

The stereomicroscopic appearance of the vasculature and circulation of groin flaps, with their epigastric pedicles divided at various time intervals, is an early diagnostic indication of flap viability. A simple and comprehensive training model, with characteristic vascular and flow changes within a single flap, is provided in rats, with pedicles transected at three to four days after the flap is raised.

Protein translocation into Escherichia coli membrane vesicles is inhibited by functional synthetic signal peptides

A synthetic peptide corresponding to the signal sequence of wild type Escherichia coli lambda-receptor protein (LamB) inhibits in vitro translocation of precursors of both alkaline phosphatase and outer membrane protein A into E. coli membrane vesicles (half-maximal inhibition at 1-2 microM). By contrast, the inhibitory effect was nearly absent in a synthetic peptide corresponding to the signal sequence from a mutant strain that harbors a deletion mutation in the LamB signal region and displays an export-defective phenotype for this protein in vivo. Two peptides derived from pseudorevertant strains that arose from the deletion mutant and exported LamB in vivo were found to inhibit in vitro translocation with effectiveness that correlated with their in vivo export ability. Controls indicated that these synthetic signal peptides did not disrupt the E. coli membrane vesicles. These results can be interpreted to indicate that the presequences of exported proteins interact specifically with a receptor either in the E. coli inner membrane or in the cytoplasmic fraction. However, biophysical data for the family of signal peptides studied here reveal that they will spontaneously insert into a lipid membrane at concentrations comparable to those that cause inhibition. Hence, an indirect effect mediated by the lipid bilayer of the membrane must be considered.

Effects of nucleotides on ATP-dependent protein translocation into Escherichia coli membrane vesicles

We have shown previously that Escherichia coli can translocate the same protein either co- or posttranslationally and that ATP hydrolysis is essential for the posttranslational translocation of the precursors of alkaline phosphatase and OmpA protein into inverted E. coli membrane vesicles. ATP-dependent protein translocation has now been further characterized. In the absence of exogenous Mg2+, dATP, formycin A-5'-triphosphate, ATP-alpha-S, and N1-oxide-ATP could replace ATP, but many other nucleotides were not only ineffective but inhibited ATP-dependent translocation. The inhibitors included nonhydrolyzable ATP analogs, ATP-gamma-S, 8-azido-ATP, AMP, ADP, cyclic AMP, PPi, and tripolyphosphate. On the other hand, adenosine, adenosine 5'-tetraphosphate, and N1,N6-etheno-ATP neither supported nor inhibited translocation. Moreover, photoaffinity labeling of azido-adenine nucleotides rendered membranes inactive for subsequent ATP-dependent protein translocation. These results suggest that protein translocation involves at least an ATP-binding site in the membrane and hydrolysis of ATP and that both the adenosine and phosphate moieties of ATP play a role.

Effect of tolazamide on basal ketogenesis, glycogenesis, and gluconeogenesis in liver obtained from normal and diabetic rats

The effect of tolazamide on in vitro rates of gluconeogenesis, ketogenesis, and glycogenesis was determined in liver tissue from fasted normal and diabetic rats. Hormones were not added to the incubation mixture. Two concentrations of the drug were tested, one of which was therapeutic (40 micrograms/ml) and other immoderately elevated (400 micrograms/ml). Neither drug concentration affected hepatic glycogen synthesis. However, the low dose of tolazamide inhibited ketogenesis in the diabetic liver by 39% and in the control liver by 32%; oxidative CO2 production from palmitate was reduced in parallel with ketogenesis. The drug did not alter ketogenesis in isolated intact mitochondria. Similarly, this same therapeutic dose curtailed hepatic gluconeogenesis only in control liver (74% inhibition); this reaction was unaltered by this drug concentration in the explants derived from the diabetic rats. The logarithmically higher dose inhibited hepatic gluconeogenesis in both control and diabetic liver tissue by 56% and 51%, respectively. Hence, possibly acting at a postreceptor site, therapeutic concentrations of tolazamide can decrease rat hepatic in vitro gluconeogenesis and ketogenesis.

A successful replantation of rat ear

This article presents a successful replantation of a completely severed rat ear. The procedure include re-union of the tubal cartilage and anastomosis of the surgically divided external carotid artery and posterior facial vein.

Influence of isoflurane on hypoxic pulmonary vasoconstriction in dogs

The authors studied the influence of locally administered isoflurane anesthesia on the pulmonary vascular response to regional alveolar hypoxia (hypoxic pulmonary vasoconstriction [HPV]) over a range of cardiac outputs (COs) in seven mechanically ventilated, closed-chest dogs. The right lung was ventilated with 100% O2 throughout the study. The left lung was ventilated with either 100% O2 (normoxia) or an hypoxic gas mixture (hypoxia). Different alveolar concentrations of isoflurane (0, 1, and 2.5 MAC) were administered to the left lung in a randomized sequence. The CO was altered by opening and closing surgically produced arteriovenous fistulae, at all isoflurane concentrations, and by hemorrhage at 0 MAC isoflurane. The magnitude of the HPV response was measured by differential CO2 elimination in the absence of isoflurane and by venous admixtures in all phases. During normoxia, the left lung effective flow (QL%) measured from differential CO2 excretion was 39.9 +/- 1.2% of the total blood flow and decreased to 18.8 +/- 2.6% when ventilated with the hypoxic gas mixture. Venous admixture (QVA/QT%) was significantly correlated with QL% during hypoxic ventilation in the absence of isoflurane. QVA/QT% was 22.3 +/- 2.7% during hypoxia with normal CO, and it increased significantly to 27.7 +/- 1.1% when the CO was increased 43%. It was not significantly altered (23.6 +/- 3.6%) when the CO was decreased by 54%. Isoflurane 2.5 MAC significantly increased QVA/QT% during hypoxic ventilation of the left lung to 33.9 +/- 2.6% with low CO and 35.4 +/- 1.7% with normal CO. Isoflurane 1 MAC increased QVA/QT% to 27.2 +/- 2.7% with normal CO and 28.1 +/- 2.6% with high CO.(ABSTRACT TRUNCATED AT 250 WORDS)

Spiral interrupted suturing technique for microvascular anastomosis: a comparative study

This is an experimental study comparing the suturing time and patency rate of a spiral interrupted suturing technique to those of conventional interrupted and continuous suturing technique in end-to-end as well as end-to-side anastomosis. The spiral interrupted suturing technique requires less time for either end-to-end or end-to-side anastomosis than conventional interrupted suturing technique, and does not result in stenosis as shown in the venous end-to-end anastomosis by continuous suturing technique.