Hydrogen sulfide and miR21 are suitable biomarkers of hypoxic exposure

Hypoxia is the reduction of alveolar partial pressure of oxygen ([Formula: see text]). Military members and people who practice recreational activities from moderate to high altitudes are at risk for hypoxic exposure. Hypoxemia's signs and symptoms vary from asymptomatic to severe responses, such as excessive hypoxic ventilatory responses and residual neurobehavioral impairment. Therefore, it is essential to identify hypoxia-induced biomarkers to indicate people with exposure to hypoxia. Advances have been made in understanding physiological responses to hypoxia, including elevations in circulating levels of endothelin 1 (ET-1) and microRNA 21 (miR-21) and reduction in circulating levels of hydrogen sulfide (H2S). Although the levels of these factors change upon exposure to hypoxia, it is unclear if these changes are sustained on return to normoxia. We hypothesize that hypoxia-induced ET-1 and miR-21 remain elevated, whereas hypoxia-reduction in H2S sustains after returning to normoxic conditions. To test this hypothesis, we exposed male rats to 6 h of 12% O2 and measured circulating levels of ET-1 and miR-21, pre, during, and posthypoxia. We found that ET-1 plasma levels increased in response to hypoxia but returned to normal levels within 30 min after the restoration of normoxia. miR-21 plasma levels and transdermal H2S emissions decreased in response to hypoxia, remaining decreased on return to normoxia, thus following the biomarker criteria. Therefore, this study supports a unique role for plasma miR21 and transdermal H2S as hypoxia biomarkers that could be used to identify individuals after exposure to hypoxia.

Abstract 288: Impaired Ischemic Myocutaneous Wound Revascularization And Transdermal H 2 S Emissions In Diabetic Rats

Introduction: Hydrogen sulfide (H 2 S) has been recognized as an important signaling molecule in cellular O 2 sensing, wound healing and angiogenesis. Studies have shown abnormal H 2 S levels in diabetic patients with cardiovascular disease. Diminished H 2 S signaling may play a causative role in diabetic foot wounds. The Transdermal Arterial Gasotransmitter Sensor (TAGS) device measures real-time H 2 S emissions through the skin. In this work, we utilize the novel TAGS device to characterize transdermal H 2 S emissions during diabetic and non-diabetic wound healing for the first time.

Methods: Dorsal peninsular-shaped myocutaneous ischemic flap wounds were created under anesthesia. Sprague Dawley (SD) and Zucker Diabetic Fatty (ZDF) rats (n=10 each) were compared. Transdermal H 2 S emissions, laser speckle contrast images (LSCI) and planimetric photos were serially taken from the wound flap area over 14 days. After animal sacrifice, healed flap tissue was collected for histologic (H&E) analysis of panniculus carnosus (skin muscle) viability as a proxy for degree of ischemic insult.

Results: ZDF rats were significantly hyperglycemic (mean 516 mg/dL vs. 201 mg/dL for SD, P=0.002). Similar mean baseline (preoperative) H 2 S emissions were observed in SD (16 ppb) and ZDF (12 ppb) rats (P=0.25). During revascularization and healing, ZDF wounds emitted significantly less H 2 S (10 ppb at day 14) as compared to SD (28 ppb at day 14, P<0.01). ZDF wounds demonstrated impaired flap engraftment and revascularization by LSCI (mean 65.6 Perfusion Units (PU) for ZDF vs. 188.0 PU for SD at day 14, p<0.01) and planimetric analysis (mean 16.6% necrosis for ZDF vs. 5.3% necrosis for SD at day 14, p=0.01). Panniculus carnosus mean myofibril count, myofibril diameter, and layer thickness were significantly decreased (p<0.01) in the ZDF cohort, suggesting greater tissue ischemic insult and muscle loss.

Conclusion: Diabetic rats have impaired wound H 2 S production and poor revascularization. These physiologic alterations are accompanied by greater wound necrosis and histologic ischemic insult. This suggests H 2 S abnormalities in diabetes may play a role in the pathogenesis of impaired wound healing and could represent a potential future therapeutic target for these difficult wounds.

A genetic map of an Australian wild Gossypium C genome and assignment of homoeologies with tetraploid cultivated cotton

Genetic diversity for traits such as fibre quality or disease resistance to microorganisms is limited in the elite cotton germplasm; consequently, cotton breeders are looking for novel alleles in the secondary or even in the tertiary gene pools. The wild Australian Gossypium species (tertiary gene pool) represent an alternative source of novel alleles. However, to use these species efficiently, enabling tools are required. Chromosome-specific molecular markers are particularly useful tools to track the transmission of this exotic genetic material into the cultivated cotton during introgression. In this study, we report the construction of a genetic linkage map of the Australian wild C-genome species Gossypium sturtianum. The map, based on an F(2) population of 114 individuals, contains 291 AFLP loci. The map spans 1697 cM with an average distance of 5.8 cM between markers. To associate C-genome chromosomes with the A and D subgenomes of cultivated cotton, 29 SSR and RFLP-STS markers were assigned to chromosomes using cultivated cotton mapped marker information. Polymorphisms were revealed by 51 AFLP primer combinations and 38 RFLP-STS and 115 SSR cotton mapped markers. The utility of transferring RFLP-STS and SSR cotton mapped markers to other Gossypium species shows the usefulness of a comparative approach as a source of markers and for aligning the genetic map of G. sturtianum with the cultivated species in the future. This also indicates that the overall structure of the G. sturtianum linkage groups is similar to that of the A and D subgenomes of cotton at the gross structural level. Applications of the map for the Australia wild C-genome species and cotton breeding are discussed.

Appearance of dissociable and cross-linked hemoglobins in the renal hilar lymph

Unlike unmodified dissociable bovine hemoglobin (UHb), cross-linked hemoglobins do not dissociate into dimers, do not cross the glomerular filter, and are retained in the plasma for a longer time. Renal peritubular capillaries, which are different from the glomerulus, allow the passage of molecules as large as albumin into the renal interstitium. Cross-linked hemoglobins should pass across these capillaries, enter the renal interstitium, and drain through the renal lymphatics. The present experiments were done in anesthetized rats to determine the appearance of UHb, an intramolecularly cross-linked tetrameric hemoglobin (DECHb), and a polymerized bovine hemoglobin (PHb) of larger molecular size into the renal hilar lymph. Renal hilar lymph samples were obtained before and after an isovolemic exchange of 2 mL/100 g rat weight of a 6% solution of each hemoglobin for blood. The behavior of a 5% solution of Evan's blue-labeled albumin was also determined for comparison. After exchange, the Initial plasma concentration of each of the proteins was in excess of 20 mg/mL. UHb appeared both in urine and lymph. DECHb, PHb, and albumin were absent from the urine but appeared promptly in the renal hilar lymph and reached concentrations at least 30% that of plasma. PHb had a significantly smaller lymph clearance (in microliters per minute) and longer plasma half-time than the other nondissociable proteins. These findings indicate that DECHb and PHb, although not filtered, pass across peritubular capillaries and readily enter the renal interstitial space. The passage of the larger molecular-sized PHb may be hindered relative to the other proteins in passage across peritubular and other systemic capillaries.

Renal response to hemodilution with albumin or crosslinked bovine hemoglobin: role of nitric oxide

The decreased hematocrit that occurs with hemodilution leads to a decrease in peripheral resistance while venous return and cardiac output increase. We determined systemic and renal responses to hemodilution with a solution of albumin or a crosslinked hemoglobin-based oxygen carrier (XLHb) and the effect of inhibition of NO synthesis on the responses to albumin. Clearance experiments were done on anesthetized rats to determine mean arterial pressure (MAP), glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and sodium excretion before and after isovolemic exchange transfusion (2 ml per 100 gm body weight) with either (1) 5% albumin (n = 5), (2) 5% albumin plus N omega-nitro-L-arginine methyl ester (L-NAME, 3.5 mg/kg; n = 6), or (3) 6% XLHb (n = 7) and after administration of L-NAME alone (n = 4). Hematocrit decreased similarly in all exchange groups (from 42 +/- 1.0 to 29 +/- 1.3). MAP decreased with albumin exchange, increased with L-NAME, and remained unchanged with albumin+L-NAME or XLHb. GFR, ERPF, and renal blood flow increased while filtration fraction and renal resistance decreased with albumin exchange; responses were the opposite with L-NAME, and with albumin+L-NAME and XLHb these parameters remained approximately the same as control values. Red cell delivery decreased with L-NAME, albumin+L-NAME, and XLHb but remained at control levels with albumin. In conclusion, renal effects of decreased hematocrit can be offset by decreased NO availability. The similarity of results with XLHb and albumin+L-NAME is consistent with NO scavenging by hemoglobin. Increased renal vascular tone with XLHb limits oxygen delivery.

Three newly identified A*24 alleles: A*2406, A*2413 and A*2414

Three previously unknown A24-related alleles were identified by PCR-SSO typing and confirmed by DNA sequencing in Australian Aboriginal populations (A*2406, 2413) and in individuals of South American descent (A*2414). A*2406 and A*2413 both have two adjacent (but different) nucleotide substitutions in codon 156 in exon 3 compared to A*2402, resulting in a single amino acid replacement in each allele. The South American A*2414 is apparently a hybrid between A2 and A24 with a segment of the A*24 sequence between codons 95 and 107 in exon 3 replaced with the A*02 sequence. Interallelic sequence exchange is the most likely mechanism in the generation of all three novel alleles. Compared to A*2402, the four amino acid substitutions in the A*2414 molecule would be expected to significantly change the shape of the peptide binding cleft, leading to selection of different peptide ligands. The single amino acid replacements in position 156 of the two Australian Aboriginal A*24 alleles may also have significant functional effects. In particular, Trp replacing Gln in position 156 (A*2406) is predicted to markedly reduce the volume of the peptide binding cleft, influence the interaction of HLA pockets with peptide side chains, and therefore, cause major changes in peptide presentation. These newly defined alleles may reflect the adaptive process of HLA genes to local environments.

Effect on serum lipids of monounsaturated oil and margarine in the diet of an Antarctic Expedition

A 13-wk dietary intervention was carried out with 23 members of the 1991 wintering party of an Australian National Antarctic Research Expedition. Canola margarine and canola cooking oil were substituted for usual dietary fats (butter, a margarine containing 28% saturated fat, a polyunsaturated margarine, and vegetable oil). Mean energy intake slowly decreased although body weight slowly increased during the 42-wk wintering-over period. During 13 wk of dietary substitution, mean total cholesterol and low-density-lipoprotein-cholesterol concentrations fell by 7.0% and 10.0%, respectively (P < 0.05, repeated-measures ANOVA). These changes were not found in a second wintering-over group that did not experience this dietary intervention. The data indicate that a relatively simple change to the food supply has the potential to produce significant beneficial changes in lipoprotein lipid profile.

HLA-DQ genotypes are associated with autoimmunity to glutamic acid decarboxylase in insulin-dependent diabetes mellitus patients

This study has investigated the genetic basis of the heterogeneous autoimmune response to glutamic acid decarboxylase (GAD) in 179 Australian patients with IDDM. Antibodies to GAD have been correlated with HLA-DQB1 alleles and genotypes, as determined by sequence-specific oligonucleotide hybridizations after polymerase chain reaction was applied to exon 2 of the DQ beta 1 gene. HLA-DQ2 was significantly increased (p < 0.01) in IDDM patients with antibodies to GAD. Antibodies to GAD were detected in 64% of 72 DQ2.8 patients, in 55% of 29 DQ2.2 or DQ8.8 patients and in 41% of 78 patients with other HLA-DQB1 genotypes. HLA-DQ genotype association with autoimmunity to GAD was statistically significant (p = 0.02) and reflected early formation of antibodies to GAD, rather than an HLA association with persistence of antibodies to GAD, since the genotype effect was more evident (p = 0.02) in those with more recent onset (0-5 years) of IDDM. Also, the HLA-DQ genotype effect was more evident in patients with IDDM onset after the age of 14 years (p = 0.003). Multivariate analysis showed that HLA-DQB1 genotypes had a more significant impact on antibodies to GAD than either duration or age of onset of IDDM. In patients with IDDM in childhood, only a minority had low-risk HLA-DQB1 genotypes (37%) when compared with those with onset in adulthood (62%) (p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Growth hormone response to clonidine in neuroleptic-free patients with multidagnostically defined schizophrenia

The role of alpha 2-adrenergic receptor sensitivity in schizophrenia was examined by measuring growth hormone (GH) response after the intravenous administration of clonidine (1.3 micrograms/kg) in 26 healthy control subjects and 26 neuroleptic-free, acutely psychotic patients with at least 1 out of 11 possible diagnoses of schizophrenia derived from a multidiagnostic psychopathological assessment. GH responses were significantly (0.01) lower than control values in schizophrenias defined by E. Bleuler, M. Bleuler, Schneider, Langfeldt, Taylor and Abrams, and Cloninger, but not in DSM-III, World Health Organization, Feighner, Kraepelian, and Research Diagnostic Criteria (RDC) schizophrenias. Eight patients with RDC schizoaffective disorder also had a blunted response. However, there were no correlations with any symptom measures. There were no differences between paranoid and nonparanoid patients, although there was a significant difference between nonparanoid patients and control subjects. These findings support the presence of noradrenergic dysfunction in some patients within the schizophrenia syndrome, possibly those whose illnesses have an affective component. The study also illustrates the need for simultaneous investigation of several different sets of diagnostic criteria for schizophrenia in neurobiological research.

Human chorionic gonadotrophin-induced suppression of serum inhibin involves reduction in ovarian inhibin alpha-subunit messenger RNA levels in the pregnant mare serum gonadotrophin-primed female rat

We have investigated the effect of administration of human chorionic gonadotrophin (hCG) to immature female rats pretreated with pregnant mare serum gonadotrophin (PMSG) on ovarian inhibin alpha-subunit mRNA, serum inhibin and circulating gonadotrophin levels. PMSG stimulation alone caused a 5-fold increase in relative inhibin alpha-subunit mRNA levels and a 12-fold increase in serum inhibin by 48 h. However, injection of hCG at 40 h suppressed PMSG-stimulated ovarian inhibin alpha-subunit mRNA and serum inhibin to levels at 48 h not statistically significantly different from controls. Serum follicle-stimulating hormone (FSH) fell after PMSG treatment, but rose after combined PMSG-hCG treatment. Serum luteinizing hormone (LH) was unchanged after PMSG alone but also rose after combined PMSG and hCG therapy. In conclusion, hCG suppresses ovarian inhibin synthesis in PMSG-stimulated immature female rats with preservation of the reciprocal relationship between inhibin and FSH. This immature female rat model therefore provides further insight into the effects of LH or hCG on granulosa cell inhibin production just prior to ovulation.

Expression of the prolactin gene in human decidua-chorion

Messenger RNA (mRNA) purified from human decidua-chorion hybridizes with a 32P-cDNA probe for human prolactin. In contrast, mRNA from human trophoblast and amnion does not hybridize to prolactin cDNA. The migration position on agarose gels of prolactin-specific mRNA from human decidua-chorion is similar to that for mRNA from ovine pituitary, suggesting a similar sized mRNA coding for prolactin in these different tissues and species. These data demonstrate unambiguously that the prolactin gene is expressed in human decidua-chorion, confirming previous immunochemical reports of prolactin production by this tissue in culture.