Ethanol modulates the VR-1 variant amiloride-insensitive salt taste receptor. II. Effect on chorda tympani salt responses

The effect of ethanol on the amiloride- and benzamil (Bz)-insensitive salt taste receptor was investigated by direct measurement of intracellular Na⁺ activity ([Na⁺]_i) using fluorescence imaging in polarized fungiform taste receptor cells (TRCs) and by chorda tympani (CT) taste nerve recordings. CT responses to KCl and NaCl were recorded in Sprague-Dawley rats, and in wild-type (WT) and vanilloid receptor-1 (VR-1) knockout mice (KO). CT responses were monitored in the presence of Bz, a specific blocker of the epithelial Na⁺ channel (ENaC). CT responses were also recorded in the presence of agonists (resiniferatoxin and elevated temperature) and antagonists (capsazepine and SB-366791) of VR-1 that similarly modulate the Bz-insensitive VR-1 variant salt taste receptor. In the absence of mineral salts, ethanol induced a transient decrease in TRC volume and elicited only transient phasic CT responses. In the presence of mineral salts, ethanol increased the apical cation flux in TRCs without a change in volume, increased transepithelial electrical resistance across the tongue, and elicited CT responses that were similar to salt responses, consisting of both a phasic component and a sustained tonic component. At concentrations <50%, ethanol enhanced responses to KCl and NaCl, while at ethanol concentrations >50%, those CT responses were inhibited. Resiniferatoxin and elevated temperature increased the sensitivity of the CT response to ethanol in salt-containing media, and SB-366791 inhibited the effect of ethanol, resiniferatoxin, and elevated temperature on the CT responses to mineral salts. VR-1 KO mice demonstrated no Bz-insensitive CT response to NaCl and no sensitivity to ethanol. We conclude that ethanol increases salt taste sensitivity by its direct action on the Bz-insensitive VR-1 variant salt taste receptor.

Relation of serum sialic acid with serum lipids in cardiac patients

Elevated serum sialic acid concentration is a risk factor for coronary heart disease in general population along with dyslipidemia. Sialic acid and lipid profile was determined in healthy subjects (Group A1 and A2) and sixty cardiac patients, divided into two groups, group B comprising of thirty male patients and group C comprising of thirty female patients. A highly significant increase was observed in the level of sialic acid and different variables of lipid profile except HDL-C in all patients. HDL-C showed a significant decrease in patients. An increase in the level of sialic acid in cardiac patients showing the implications of raised level of sialic acid in the development of cardiovascular complications.

Ethanol modulates the VR-1 variant amiloride-insensitive salt taste receptor. I. Effect on TRC volume and Na+ flux

The effect of ethanol on the amiloride- and benzamil (Bz)-insensitive salt taste receptor was investigated by the measurement of intracellular Na(+) activity ([Na(+)](i)) in polarized rat fungiform taste receptor cells (TRCs) using fluorescence imaging and by chorda tympani (CT) taste nerve recordings. CT responses were monitored during lingual stimulation with ethanol solutions containing NaCl or KCl. CT responses were recorded in the presence of Bz (a specific blocker of the epithelial Na(+) channel [ENaC]) or the vanilloid receptor-1 (VR-1) antagonists capsazepine or SB-366791, which also block the Bz-insensitive salt taste receptor, a VR-1 variant. CT responses were recorded at 23 degrees C or 42 degrees C (a temperature at which the VR-1 variant salt taste receptor activity is maximally enhanced). In the absence of permeable cations, ethanol induced a transient decrease in TRC volume, and stimulating the tongue with ethanol solutions without added salt elicited only transient phasic CT responses that were insensitive to elevated temperature or SB-366791. Preshrinking TRCs in vivo with hypertonic mannitol (0.5 M) attenuated the magnitude of the phasic CT response, indicating that in the absence of mineral salts, transient phasic CT responses are related to the ethanol-induced osmotic shrinkage of TRCs. In the presence of mineral salts, ethanol increased the Bz-insensitive apical cation flux in TRCs without a change in cell volume, increased transepithelial electrical resistance across the tongue, and elicited CT responses that were similar to salt responses, consisting of both a transient phasic component and a sustained tonic component. Ethanol increased the Bz-insensitive NaCl CT response. This effect was further enhanced by elevating the temperature from 23 degrees C to 42 degrees C, and was blocked by SB-366791. We conclude that in the presence of mineral salts, ethanol modulates the Bz-insensitive VR-1 variant salt taste receptor.

The mammalian amiloride-insensitive non-specific salt taste receptor is a vanilloid receptor-1 variant

The amiloride-insensitive salt taste receptor is the predominant transducer of salt taste in some mammalian species, including humans. The physiological, pharmacological and biochemical properties of the amiloride-insensitive salt taste receptor were investigated by RT-PCR, by the measurement of unilateral apical Na+ fluxes in polarized rat fungiform taste receptor cells and by chorda tympani taste nerve recordings. The chorda tympani responses to NaCl, KCl, NH4Cl and CaCl2 were recorded in Sprague-Dawley rats, and in wild-type and vanilloid receptor-1 (VR-1) knockout mice. The chorda tympani responses to mineral salts were monitored in the presence of vanilloids (resiniferatoxin and capsaicin), VR-1 antagonists (capsazepine and SB-366791), and at elevated temperatures. The results indicate that the amiloride-insensitive salt taste receptor is a constitutively active non-selective cation channel derived from the VR-1 gene. It accounts for all of the amiloride-insensitive chorda tympani taste nerve response to Na+ salts and part of the response to K+, NH4+ and Ca2+ salts. It is activated by vanilloids and temperature (> 38 degrees C), and is inhibited by VR-1 antagonists. In the presence of vanilloids, external pH and ATP lower the temperature threshold of the channel. This allows for increased salt taste sensitivity without an increase in temperature. VR-1 knockout mice demonstrate no functional amiloride-insensitive salt taste receptor and no salt taste sensitivity to vanilloids and temperature. We conclude that the mammalian non-specific salt taste receptor is a VR-1 variant.

Basolateral Na+-H+ exchanger-1 in rat taste receptor cells is involved in neural adaptation to acidic stimuli

The role of basolateral Na(+)-H(+) exchanger isoform-1 (NHE-1) was investigated in neural adaptation of rat taste responses to acidic stimuli, by direct measurement of intracellular pH (pH(i)) in polarized taste receptor cells (TRCs) and by chorda tympani (CT) taste nerve recordings. In TRCs perfused with CO(2)/HCO(3)(-)-free solution (pH 7.4), removal of basolateral Na(+) decreased pH(i) reversibly and zoniporide, a specific NHE-1 blocker, inhibited the Na(+)-induced changes in pH(i). The spontaneous rate of TRC pH(i) recovery from NH(4)Cl pulses was inhibited by basolateral zoniporide with a K(i) of 0.33microm. Exposure to basolateral ionomycin, reversibly increased TRC Ca(2+), resting pH(i), and the spontaneous rate of pH(i) recovery from an NH(4)Cl pulse. These effects of Ca(2+) on pH(i) were blocked by zoniporide. In in vivo experiments, topical lingual application of zoniporide increased the magnitude of the CT responses to acetic acid and CO(2), but not to HCl. Topical lingual application of ionomycin did not affect the phasic part of the CT responses to acidic stimuli, but decreased the tonic part by 50% of control over a period of about 1 min. This increased adaptation in the CT response was inhibited by zoniporide. Topical lingual application of 8-CPT-cAMP increased the CT responses to HCl, but not to CO(2), and acetic acid. In the presence of cAMP, ionomycin increased sensory adaptation to HCl, CO(2), and acetic acid. Thus, cAMP and Ca(2+) independently modulate CT responses to acidic stimuli. While cAMP enhances TRC apical H(+) entry and CT responses to strong acid, an increase in Ca(2+) activates NHE-1, and increases neural adaptation to all acidic stimuli.

Na+-H+ exchange activity in taste receptor cells

mRNA for two Na(+)-H(+)-exchanger isoforms 1 and 3 (NHE-1 and NHE-3) was detected by RT-PCR in fungiform and circumvallate taste receptor cells (TRCs). Anti-NHE-1 antibody binding was localized to the basolateral membranes, and the anti-NHE-3 antibody was localized in the apical membranes of fungiform and circumvallate TRCs. In a subset of TRCs, NHE-3 immunoreactivity was also detected in the intracellular compartment. For functional studies, an isolated lingual epithelium containing a single fungiform papilla was mounted with apical and basolateral sides isolated and perfused with nominally CO(2)/HCO(3)(-)-free physiological media (pH 7.4). The TRCs were monitored for changes in intracellular pH (pH(i)) and Na(+) ([Na(+)](i)) using fluorescence ratio imaging. At constant external pH, 1) removal of basolateral Na(+) reversibly decreased pH(i) and [Na(+)](i); 2) HOE642, a specific blocker, and amiloride, a nonspecific blocker of basolateral NHE-1, attenuated the decrease in pH(i) and [Na(+)](i); 3) exposure of TRCs to basolateral NH(4)Cl or sodium acetate pulses induced transient decreases in pH(i) that recovered spontaneously to baseline; 4) pH(i) recovery was inhibited by basolateral amiloride, 5-(N-methyl-N-isobutyl)-amiloride (MIA), 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), HOE642, and by Na(+) removal; 5) HOE642, MIA, EIPA, and amiloride inhibited pH(i) recovery with K(i) values of 0.23, 0.46, 0.84, and 29 microM, respectively; and 6) a decrease in apical or basolateral pH acidified TRC pH(i) and inhibited spontaneous pH(i) recovery. The results indicate the presence of a functional NHE-1 in the basolateral membranes of TRCs. We hypothesize that NHE-1 is involved in sour taste transduction since its activity is modulated during acid stimulation.

Evaluation of Pathogenic Potential of Avian Influenza Virus Serotype H9N2 in Chickens

Recently seven isolates of avian influenza virus (AIV) serotype H9N2 recovered from an outbreak of AI were analyzed on the basis of their biological and molecular characteristics. All the isolates belonged to the low-pathogenicity group of AIV. To further evaluate their pathogenic potential in association with other organisms, an isolate was inoculated experimentally in chickens using different routes and subsequently challenged with infectious bronchitis virus, Ornithobacterium rhinotracheale or Escherichia coli. The virus isolation and seromonitoring data revealed a significant role of Escherichia coli in aggravating the clinical condition of the birds earlier infected with AIV (H9N2). The AIV-antigen was detected in lung, trachea, kidney, and cloacal bursa among the infected birds, using immunofluorescent antibody technique. In another experiment, chickens that were immunosuppressed chemically showed high mortality when challenged with AIV H9N2. The results indicated that this low pathogenicity AIV (H9N2) isolate could produce severe infection depending on the type of secondary opportunistic pathogens present under field conditions. This may explain the severity of infection with the present H9N2 outbreak in the field. A prolonged antibacterial therapy in flocks infected with AIV H9N2 and use of oil-based vaccine at an early age in new flocks has helped to control this infection and the disease.

Modulation of rat chorda tympani NaCl responses and intracellular Na+ activity in polarized taste receptor cells by pH

Mixture interactions between sour and salt taste modalities were investigated in rats by direct measurement of intracellular pH (pH(i)) and Na(+) activity ([Na(+)](i)) in polarized fungiform taste receptor cells (TRCs) and by chorda tympani (CT) nerve recordings. Stimulating the lingual surface with NaCl solutions adjusted to pHs ranging between 2.0 and 10.3 increased the magnitude of NaCl CT responses linearly with increasing external pH (pH(o)). At pH 7.0, the epithelial sodium channel (ENaC) blocker, benzamil, decreased NaCl CT responses and inhibited further changes in CT responses induced by varying pH(o) to 2.0 or 10.3. At constant pH(o), buffering NaCl solutions with potassium acetate/acetic acid (KA/AA) or HCO(3)(-)/CO(2) inhibited NaCl CT responses relative to CT responses obtained with NaCl solutions buffered with HEPES. The carbonic anhydrase blockers, MK-507 and MK-417, attenuated the inhibition of NaCl CT responses in HCO(3)(-)/CO(2) buffer, suggesting a regulatory role for pH(i). In polarized TRCs step changes in apical pH(o) from 10.3 to 2.0 induced a linear decrease in pH(i) that remained within the physiological range (slope = 0.035; r(2) = 0.98). At constant pH(o), perfusing the apical membrane with Ringer's solutions buffered with KA/AA or HCO(3)(-)/CO(2) decreased resting TRC pH(i), and MK-507 or MK-417 attenuated the decrease in pH(i) in TRCs perfused with HCO(3)(-)/CO(2) buffer. In parallel experiments, TRC [Na(+)](i) decreased with (a) a decrease in apical pH, (b) exposing the apical membrane to amiloride or benzamil, (c) removal of apical Na(+), and (d) acid loading the cells with NH(4)Cl or sodium acetate at constant pH(o). Diethylpyrocarbonate and Zn(2+), modification reagents for histidine residues in proteins, attenuated the CO(2)-induced inhibition of NaCl CT responses and the pH(i)-induced inhibition of apical Na(+) influx in TRCs. We conclude that TRC pH(i) regulates Na(+)-influx through amiloride-sensitive apical ENaCs and hence modulates NaCl CT responses in acid/salt mixtures.

Decrease in rat taste receptor cell intracellular pH is the proximate stimulus in sour taste transduction

Taste receptor cells (TRCs) respond to acid stimulation, initiating perception of sour taste. Paradoxically, the pH of weak acidic stimuli correlates poorly with the perception of their sourness. A fundamental issue surrounding sour taste reception is the identity of the sour stimulus. We tested the hypothesis that acids induce sour taste perception by penetrating plasma membranes as H(+) ions or as undissociated molecules and decreasing the intracellular pH (pH(i)) of TRCs. Our data suggest that taste nerve responses to weak acids (acetic acid and CO(2)) are independent of stimulus pH but strongly correlate with the intracellular acidification of polarized TRCs. Taste nerve responses to CO(2) were voltage sensitive and were blocked with MK-417, a specific blocker of carbonic anhydrase. Strong acids (HCl) decrease pH(i) in a subset of TRCs that contain a pathway for H(+) entry. Both the apical membrane and the paracellular shunt pathway restrict H(+) entry such that a large decrease in apical pH is translated into a relatively small change in TRC pH(i) within the physiological range. We conclude that a decrease in TRC pH(i) is the proximate stimulus in rat sour taste transduction.

Bone marrow changes in human malaria: a retrospective study

The bone marrow reports of 1966 patients admitted to a provincial teaching hospital between January, 1992 to April, 1995 were retrospectively analyzed. Twenty-six (1.3%) bone marrows showed the presence of malarial parasites. Sixteen (62%) patients had Plasmodium falciparum 9 (34%) Vivax malaria and one (4%) mixed infection. All these patients gave a history of prolonged illness and had low parasite counts. Plasmodium vivax malaria was not associated with any significant pathology in the bone marrow, except iron deficiency anaemia. The bone marrows with Plasmodium falciparum malaria showed myeloid hyperplasia, erythroid hyperplasia, megaloblastosis and hypoplasia in different proportions. No evidence of dyserythropoiesis was found in this series. The possible mechanisms producing these changes and the factors responsible for the discrepancy in bone marrow findings in different geographical areas are discussed.

Tumor necrosis factor in falciparum malaria

To investigate the relationship of TNFalpha levels to Plasmodium falciparum (PF) infection, plasma TFNalpha concentrations were measured in Pakistani adults and children with mind, severe, cerebral and chronic falciparum malaria and healthy (control) subjects. The initial geometric mean plasma concentrations of TFNalpha in adult patients with severe malaria (187.6 pg/mL) were significantly higher than mild malaria patients (87.1 pg/mL, P < 0.001). TNFalpha levels were not correlated to parasite density, cerebral malaria, young age, hypoglycemia or fatal outcome; however, they were associated with severe anemia, and hepatic and kidney dysfunction. TNFalpha levels were not significantly increased in 16 patients with hyperparasitemia and were significantly elevated (P < 0.02) in chronic malaria patients as compared to control subjects. TNFalpha levels were elevated independently in patients with anemia, hypoglycemia (P < 0.001, P < 0.05), and hepatic and kidney (P < 0.001 each) dysfuntion. In this study, high TNFalpha levels were associated with several manifestations of severe malaria and were not specific to cerebral malaria and hyperparasitemia.

Haematological changes in falciparum malaria and tumor necrosis factor

Tumor necrosis factor and various haematological parameters were studied in 90 patients suffering from falciparum malaria. They were divided into three groups on the basis of haemoglobin level. The difference in haemoglobin level between group-1 (Hb < 7 gm/dl) and group-2 (Hb 7-10 gm/dl), as well as group-1 and group-3 was statistically significant. The geometric mean TNF alpha concentrations in group-1 (193.9 pg/ml) and group-2 (132.2 pg/ml) were higher as compared to group-3; however, the difference was statistically non-significant. The TNF concentration in group-2 correlated negatively with haemoglobin level (r = .43, p = .05). As a whole, 21% patients had leukocytosis, 3% leukopenia, 46% increased ESR and 26% elevated levels of fibrin degradation products. The platelet count was done only in 4 patients with bleeding problems. Twenty-five healthy subjects were included in the study as controls. The difference between TNF and haemoglobin level in group-1 and controls was statistically significant (p < .05, p < .001 each). The role of tumor necrosis factor in the production of these changes is discussed.

Immunosuppressive potential and pathogenicity of an avian adenovirus isolate involved in hydropericardium syndrome in broilers

The role of avian adenovirus isolate PARC-1 as an immunosuppressive agent was investigated using a Newcastle disease virus (NDV) vaccine immune response procedure. The immunosuppressive effect on the humoral immune response was investigated up to 21 days after inoculation with adenovirus. Infected chickens showed a serologic response to NDV that was reduced compared with that of the controls. To further investigate the effect of the virus on major lymphoid organs, the pattern of virus dissemination in various organs was studied at various time intervals after inoculation. Spleen, thymus, bursa of Fabricius, and cecal tonsils of broilers were examined using a dot-immunobinding assay. The virus was found to have a predilection for lymphoid organs, and virus from lymphoid organs was capable of producing disease when inoculated into healthy chickens. The relationship of virus predilection to its immunosuppressive effect also was studied.

Heroin addiction and sex hormones in males

To investigate the effects of illicit heroin abuse on the endocrine system a study was carried out in North West Frontier Province (NWFP) where heroin addiction is prevalent. Sixty-eight subjects were included in this study. Thirty-three were untreated heroin addicts visiting "drug abuse treatment centres" in Peshawar and 35 age matched normal males. Urine samples of all addicts showed the presence of morphine. The serum concentrations of testosterone (T) in addicts was 228 ng/ml, leutinizing hormone (LH) 10.7 mlU/ml and folical stimulating hormone (FSH) 4.9 mlU/ml whereas the corresponding values for control males were T 630 ng/ml, LH 14.3 mlU/ml and FSH mlU/ml, respectively. Heroin exerts a depletion effect on T and FSH levels in more or less all the groups studied irrespective of age, amount of heroin intake per day and period of contact with heroin. LH levels remained affected and are within clinically accepted normal range.

Chediak-Higashi syndrome: clinical, hematologic, and immunologic improvement after splenectomy

A 10-year-old boy with Chediak-Higashi syndrome in accelerated phase failed to respond to treatment with ascorbic acid, vincristine, and prednisone. Splenectomy resulted in clinical, hematologic, and immunologic improvement: his leukocyte chemotactic and phagocytic functions returned to normal. We suggest that splenectomy be considered in treatment of the accelerated phase of Chediak-Higashi syndrome unresponsive to other forms of therapy.

An infant with multiple congenital abnormalities and biochemical findings suggesting a variant of galactosialidosis

A female newborn probably with a variant form of galactosialidosis is described. The patient, in addition to the common findings seen in early infantile forms of classical galactosialidosis, displayed an unusual combination of congenital malformations including complex cyanotic congenital heart disease with dextrocardia and situs inversus.

Effect of malathion and methyl-parathion on rat liver enzymes

The effect of sub-lethal doses of Malathion and Methyl-parathion was studied on the rat liver enzymes. Intravenous administration of both insecticides at weekly interval for four weeks resulted in increase in heart and spleen weight. Short term (24 hr.) and long term (4 weeks) treatment with insecticides resulted in increased specific activities of liver enzymes, Acid phosphatase, Alkaline phosphatase, Glutamate dehydrogenase, Glutamate oxaloacetate transaminase and Glutamate pyruvate transaminase. The increase in enzyme activity was not as profound when the insecticide administration was spread over 4 weeks. Malathion had greater effect than Methyl-parathion on the biochemical parameters studied.

Effect of malathion and methyl-parathion on rat liver enzymes

The effect of sub-lethal doses of Malathion and Methyl-Parathion was studied on the rat liver enzymes. Intravenous administration of both insecticides at weekly interval for four weeks resulted in increase in weight of various tissues, i.e., heart and spleen. Short term (24 hr) and long term (4 weeks) treatment with insecticides resulted in increased specific activities of liver enzymes, Acid phosphatase, Alkaline phosphatase, Glutamate dehydrogenase, Glutamate oxaloacetate transaminase and Glutamate pyruvate transaminase. The increase in enzyme activity was not as profound when the insecticide administration was spread over 4 weeks. Malathion had greater effect than Methyl-parathion on the biochemical parameters studied.

Determinants of hospital charges for coronary artery bypass surgery: the economic consequences of postoperative complications

This is a prospective study of 500 consecutive patients having coronary artery bypass surgery; mean hospital charge from time of surgery to discharge was +11,900 +/- 12,700. Multiple regression analysis was performed using preoperative variables and postoperative complications. No preoperative clinical feature was a significant predictor of higher average charge. Sternal wound infection (p = 0.0001), respiratory failure (p = 0.0001) and left ventricular failure (p = 0.017) were associated with higher average hospital charge. The absence of any complication predicted a lower average charge, and postoperative death (4.4 +/- 4.5 days after surgery) was also associated with lower average charge. A cost equation was developed: hospital charge equalled $11,217 + $41,559 of sternal wound infection, + $28,756 for respiratory failure, + $5,186 for left ventricular failure, - $1,798 for no complication and - $6,019 for death. Recognition of the influence of complications on charges suggests that low average charges can only be achieved by surgical programs with a low complication rate.

Isoniazid acetylation and polymorphism in humans

Phenotypes of slow and fast acetylators of isoniazid (INH) were determined in 157 subjects (80 normals and 77 patients with tuberculosis) from the twin cities of Rawalpindi and Islamabad. Plasma INH concentrations were determined chemically six hours after the drug ingestion. The findings indicate that 31.8% subjects were fast acetylators of the drug.

Cervicofacial sinuses

One hundred consecutive cases of cervicofacial sinuses are reviewed in terms of aetiology, diagnosis and subsequent management. One hundred and thirty-eight cases recorded in the world literature are reviewed for comparison.