Downregulation of inwardly rectifying potassium channel 5.1 expression in C57BL/6J cochlear lateral wall / 华中科技大学学报（医学）（英德文版）

Age-related hearing loss (AHL) is one of the most common sensory disorders among elderly persons. The inwardly rectifying potassium channel 5.1 (Kir5.1) plays a vital role in regulating cochlear K(+) circulation which is necessary for normal hearing. The distribution of Kir5.1 in C57BL/6J mice cochleae, and the relationship between the expression of Kir5.1 and the etiology of AHL were investigated. Forty C57BL/6J mice were randomly divided into four groups at 4, 12, 24 and 52 weeks of age respectively. The location of Kir5.1 was detected by immunofluorescence technique. The mRNA and protein expression of Kir5.1 was evaluated in mice cochleae using real-time polymerase-chain reactions (RT-PCR) and Western blotting respectively. Kir5.1 was detected in the type II and IV fibrocytes of the spiral ligament in the cochlear lateral wall of C57BL/6J mice. The expression levels of Kir5.1 mRNA and protein in the cochleae of aging C57BL/6J mice were down-regulated. It was suggested that the age-related decreased expression of Kir5.1 in the lateral wall of C57BL/6J mice was associated with hearing loss. Our results indicated that Kir5.1 may play an important role in the pathogenesis of AHL.

Correlation among monovalent cations [Na[+], K[+]] and serum rennin in essential hypertensive subjects

To evaluate the changes in serum level of Monovalent cations [Na[+] and K[+]] in hypertensive patients in addition to observe correlation of cations with serum Renin in such patients. Study was conducted at the Biochemistry Department of Basic Medical Sciences Institute [BMSI], Jinnah Postgraduate Medical Centre, Karachi under the supervision of Khemomal A. Karira since June 2006 July 2007. A total of seventy-five subjects were included, out of which forty patients were suffering from essential hypertension and thirty-five were normal healthy subjects. The serum level of monovalent cations was measured by flame photometry, rennin by RIA, glucose, urea and creatinine by chemical methods. The results of our study show that there is definite cat ions derangement in essential hypertension; serum sodium is significantly high [p<0.001] while potassium is significantly low [p<0.001] in hypertensives. Similarly these cations showed significant correlation with systolic and diastolic blood pressure; sodium had significant positive correlation [r-value0.463 and 0.426] while potassium had significant negative correlation [r-value-0.781 and - 0.766]. The glucose, urea and creatinine show non-significant results when compared to normotensives. In addition rennin has positive correlation [r value 0.485 and 0.467] with systolic and diastolic blood pressure respectively. Our findings suggest that cat ions and rennin should be measured in hypertensives. Present study was performed on a small sample size and provides a baseline data of cations and rennin in hypertensive subjects, so we recommend that same type of study should be carried out on large sample size to assess the importance of above parameters of hypertensives

Effect of Na+ ions on pH-dependent conformational changes in brush border sucrase-isomaltase in mice intestine.

Intestinal brush border sucrase-isomaltase (sucrose D-glucosidase E.C. 3.2.1.48, E.C. 3.2.1.10) exhibits pH-dependent stimulatory or inhibitory effects in response to Na+ ions. However, whether the enzyme undergoes conformational modulations as a function of pH and in the presence of alkali metal ions is not known. In this paper, we investigated the structural and functional relationship of purified murine sucrase in response to pH and Na+ ions using UV-CD fluorescence and spectroscopic studies. Kinetic studies revealed that at pH 5.0, the enzyme activation by Na+ ions was V-type, which changed to K-type at pH 7.2, whereas at alkaline pH (8.5), Na+ ions inhibited the enzyme activity and inhibition was uncompetitive in nature, affecting both the Km and Vmax components. Far UV-CD spectra of protein at pH 7.2 in the absence and presence of Na+ were almost overlapping, suggesting that secondary structure of protein was not affected upon addition of the salt. However, near UV-CD spectra indicated marked alterations in the tertiary structure of protein in presence of 50 mM Na+ ions. Increase in pH from 7.2 to 8.5 resulted in a marked rise in fluorescence intensity and red shift in lambda max due to tryptophan residues in the enzyme molecule. These findings suggested that alterations in enzyme activity as a function of pH and Na+ ions was associated with ionization of key amino acid residues together with structural modifications in the enzyme conformation around neutral or alkaline pH.

Effect of mono-valent anions on active, passive tensions and tension equilibrium length of gastrocnemii of Uromastix Hardwickii

The length tension relationship has been used to determine the contractile and elastic state of the muscle. However, the shape of the active and passive tensions has been found to vary from muscle to muscle and in different animals as well. It depends upon the muscle architecture and specific function it performs. The change in the state of a skeletal muscle produced under the influence of chemical agents is not evaluated for the parameters obtained from the length tension relation. In the present study an attempt has been made to observe the effects of mono-valent anion on the contractile characteristics of isolated Gastrocnemius muscles of Uromastix. The results demonstrated that both the active and passive tensions changed on treatment with mono-valent anions with a shift in their curves. This change was statistically significant for active tensions. Further, Tension equilibrium length [TEL] also affected significantly. It is concluded that length tension parameter, TEL < resting length [Lo] is also a useful indicator of muscle state representing dominant elasticity under the influence of mono-valent anions. It can be used to express the state of different contractile and elastic characters of the skeletal muscle

A Case of Recovery from Suspended Animation caused by Puffer fish Poisoning: a case report

Tetrodotoxin is a neurotoxin produced by about 90 species of puffer fish and causes paralysis of central nervous system and peripheral nerves by blocking the movement of all monovalent cations. Ingestion of tetrodotoxin produces clinical manifestations such as paresthesias(within 10-45 min), vomiting, lightheadedness, salivation, muscle twitching, dysphagia, difficulty in speaking, convulsion and death that expressed by cardiopulmonary arrest with loss of brain stem reflex sometimes. Tetrodotoxin prevents or delays ischemia induced neuronal death by way of following 3 mechanisms. Firstly, it reduces the energy demand of the brain tissues. Secondly, it delays or even prevents anoxic depolarization. Finally, it diminishes ischemia induced cell swelling and cerebral edema. We report a case of puffer fish poisoning which presented with cardiopulmonary arrest and loss of brain stem reflex, but completely recovered by aggressive cardiopulmonary resuscitation.

Physico-chemical studies on activity functions in some mixed solvents I Studies on lithium sodium and potassium hydroxide solutions in methanol water mixtures

The function of glass electrode, as a measure of acidity in terms of pH value, was studied for LiOH, NaOH and KOH solutions in methanol-water mixtures of different composition. The slopes of linear plots relating e.m.f. and pH values at different temperatures agreed well with those calculated theoritically. This indicated that the glass electrode behaved strictly as H2 electrode in all test solutions. The validity of Dole's theory of acid error delta E for the glass electrode indifferent alkali solutions was investigated. The number of water molecules associated with .the proton, in its migration from the solution into the glass surface, was determined and found to be unity. An attempt was also made to calculate the deviation delta of the pH-meter readings R[x] from the operational pH[j] values and the corresponding liquid junction potentials E[j] as well. delta and E[j] were found to be complex functions of alkali content, solvent composition and temperature probably due to changes in solvation and acidity coefficients of the ions in solution and also to the dielectric constant and basicity with additions of methanol to the purely aqueous solutions