Exploring the impact of high-altitude de-acclimatization on renal function: The roles of oxidative and endoplasmic reticulum stress in rat models

BACKGROUND

High-altitude de-acclimatization (HADA) significantly impacts physiological functions when individuals acclimatize to high altitudes return to lower altitudes. This study investigates HADA's effects on renal function and structure in rats, focusing on oxidative and endoplasmic reticulum stress as potential mechanisms of renal injury.

OBJECTIVE

To elucidate the pathophysiological mechanisms of renal damage in HADA and evaluate the efficacy of antioxidants Vitamin C (Vit C) and tauroursodeoxycholic acid (TUDCA) in mitigating these effects.

METHODS

88 male Sprague-Dawley rats were randomly divided into a control group, a high-altitude (HA) group, a high-altitude de-acclimatization (HADA) group, and a treatment group. The control group was housed in a sea level environment (500 m), while the HA, HADA, and treatment groups were placed in a simulated high-altitude chamber (5000 m) for 90 days. After this period, the HA group completed the modeling phase; the HADA group was further subdivided into four subgroups, each continuing to be housed in a sea level environment for 3, 7, 14, and 30 days, respectively. The treatment group was split into the Vit C group, the TUDCA group, and two placebo groups, receiving medication for 3 consecutive days, once daily upon return to the sea level. The Vit C group received 100 mg/kg Vit C solution via intravenous injection, the TUDCA group received 250 mg/kg TUDCA solution via intraperitoneal injection, and the placebo groups received an equivalent volume of saline similarly. Serum, urine, and kidney tissues were collected immediately after the modeling phase. Renal function and oxidative stress levels were assessed using biochemical and ELISA methods. Renal histopathology was observed with H&E, Masson's trichrome, PAS, and PASM staining. Transmission electron microscopy was used to examine the ultrastructure of glomeruli and filtration barrier. TUNEL staining assessed cortical apoptosis in the kidneys. Metabolomics was employed for differential metabolite screening and pathway enrichment analysis.

RESULTS

Compared to the control and HA groups, the HADA 3-day group (HADA-3D) exhibited elevated renal function indicators, significant pathological damage, observable ultrastructural alterations including endoplasmic reticulum expansion and apoptosis. TUNEL-positive cells significantly increased, indicating heightened oxidative stress levels. Various differential metabolites were enriched in pathways related to oxidative and endoplasmic reticulum stress. Early intervention with Vit C and TUDCA markedly alleviated renal injury in HADA rats, significantly reducing the number of apoptotic cells, mitigating endoplasmic reticulum stress, and substantially lowering oxidative stress levels.

CONCLUSION

This study elucidates the pivotal roles of oxidative and endoplasmic reticulum stress in the early-stage renal injury in rats undergoing HADA. Early intervention with the Vit C and TUDCA significantly mitigates renal damage caused by HADA. These findings provide insights into the pathophysiological mechanisms of HADA and suggest potential therapeutic strategies for its future management.

[Incidence and related factors of antiviral drug resistance in HIV-infected pregnant and postpartum women in some areas of three western provinces of China from 2017 to 2019]

Objective: To analyze the incidence and related factors of drug resistance in HIV-infected pregnant and postpartum women in some areas of three western provinces of China from 2017 to 2019. Methods: From April 2017 to April 2019, face-to-face questionnaires and blood sample testing were conducted in all health care institutions providing maternal and perinatal care and midwifery-assisted services in 7 prevention of mother-to-child transmissi project areas in Xinjiang, Yunnan and Guangxi provinces/autonomous regions. Information was collected during the perinatal period and viral load, CD4+T lymphocytes and drug resistance genes were detected at the same time. The multivariate logistic regression model was used to analyze the relationship between different factors and drug resistance in HIV-infected pregnant and postpartum women. Results: A total of 655 HIV-infected pregnant and postpartum women were included in this study. The incidence of drug resistance was 3.4% (22/655), all of whom were cross-drug resistant. The rate of low, moderate and high drug resistance was 2.1% (14/655), 1.2% (8/655) and 0.8% (5/655), respectively. The drug resistance rate in the people who had previously used antiviral drugs was 1.9% (8/418), and the drug resistance rate in the people who had not used drugs was 5.9% (14/237). The NNRTI drug resistance accounted for 2.8% (18/655) and the NRTI drug resistance rate was 2.5% (16/655). The multivariate logistic regression model showed that the risk of HIV resistance was lower in pregnant women who had previously used antiviral drugs (OR=0.32, 95%CI: 0.11-0.76). Conclusion: Strengthening the management of antiviral drug use and focusing on pregnant and postpartum women who have not previously used antiviral drugs can help reduce the occurrence of drug-resistant mutations. Personalized antiviral therapy should be considered to achieve viral inhibition effects in clinical practice.

A single nucleotide polymorphism in GABAA receptor isoforms is potentially responsible for isoflurane sensitivity in mice

GABAA receptors are chloride channels in the brain that are activated by binding with g-aminobutyric acid (GABA). The cDNA sequences of GABAA receptor subunits from two strains of mice with different sensitivities to isoflurane were compared to identify nucleotide mutations. Included 80 mice from two strains with different sensitivities to isoflurane on C57BL/6 background. Forty mice were from an isoflurane-sensitive strain (S group) and 40 mice were from a resistant strain (R group). RNA was extracted from brains of the mice, and cDNA were reverse transcribed using AMV reverse transcriptase. The amplified products were processed, sequenced, and analyzed for differences between the two strains. Chi-square analysis was performed to compare differences in nucleotide mutation frequencies between the two strains. No differences were identified in the α1-6, β2, β3, or γ1-3 nucleotide sequences and no single nucleotide polymorphisms were found in the comparison with the GenBank sequence for the GABAA receptor subunit. A single nucleotide polymorphism (SNP) at the nucleotide position 462 (C/G) in the β1 sequence was found. This SNP was observed in 5 mice from the sensitive strain and in 36 mice from the resistant strain. The Fischer exact test (P < 0.01) was used to compare two strains of mice for SNP in the cDNA sequence of the β1 subunit. Additional studies are required to understand whether the GABAA receptor is a specific target of inhaled anesthetic action or whether the identified SNP affects the action of the volatile anesthetic.

Normal gestation after 5 years on home parenteral nutrition

A case of normal gestation after 5 years on HPN is reported. The patient had her entire jejunum and ileum and right colon resected because of gangrene and has subsisted normally on HPN ever since. From the second trimester on, her HPN formula was supplemented to meet the requirement for growth and development of the foetus. Anaemia, hypoalbuminaemia, low plasma zinc levels and jaundice became manifest in the final trimester. These responded readily to readjustment of her HPN formula. A normal baby weighing 2020 g was delivered by Caesarean section at 36 weeks. Long-term HPN, final trimester abnormalities and HPN formula adjustments are discussed.

[Recent progress of study on single nucleotide polymorphisms]

Single nucleotide polymorphisms (SNPs) is a new genetic marker system following RFLP and microsatellite polymorphism. It has been shown to have the characteristics of high-density, inheritance stability and facilitation in analysis automation. SNPs can be detected by electrophoresis, endonuclease-cleavage, PCR and sequencing, and can be used extensively in gene mapping, disease-correlativity analysis, population genetics and drug research.

[Inhibition of ERK1/2 activity and c-fos mRNA after coronary artery balloon injury by intracoronary radiation in swine]

The effect of intracoronary radiation on extracellular signal regulated kinase 1/2 (ERK1/2) activity and c-fos mRNA after coronary artery balloon injury was investigated in swine. Twenty three swines were randomly divided into a radiation group and a control group after coronary balloon over stretch. The dilated segments in the radiation group were exposed to a dose of 20 Gy by a catheter based radiation system. The animals were sacrificed at 3 (6 swines from each group) and 30 days (6 swines from radiation group and 5 from control group) after the operation. The injured segments were processed to examine c-fos gene expression by reverse transcription polymerase chain reaction (RT PCR) and to measure the activity of ERK1/2 biochemically. Intracoronary radiation decreased significantly the ERK1/2 activity and gene expression of c-fos in the radiation treated animals 3 days after coronary balloon injury (20.5%,P<0.01; 47.7%,P<0.05), but neither ERK1/2 activity nor c-fos gene expression was significantly affected by endovascular radiation in animals 30 days after balloon injury. Therefore, both ERK1/2 and c-fos may be involved in inhibiting restenosis.

[Surgical treatment of atherosclerotic occlusion of lower extremities]

27 patients with atherosclerotic occlusion of lower extremities were admitted from January 1988 to December 1992. Those patients underwent various kinds of bypass operations, with an effective rate of 86.8%. Some factors influencing the operative effect are discussed.

Blood pressure and life style in the People's Republic of China: three samples in the INTERSALT Study

In INTERSALT, the International Cooperative Study on Electrolytes and Blood Pressure, three centres located in the People's Republic of China (PRC) had distinctive patterns of BP and of life style variables that, in INTERSALT overall, were found to relate to BP. The PRC centres had low body mass index (BMI) and alcohol consumption but high urinary sodium and sodium/potassium ratio (Na/K). Compared with 45 other INTERSALT centres, average BMI was 22.7 vs. 25.4 and alcohol consumption was 32% vs. 61%, with heavy drinking 3% vs. 14%. However, Na/K in the PRC was 6.7 vs. 3.2 in the other centres. This combination of factors may underlie the BP pattern observed. While mean BP in the PRC was lower than in the 45 centres (-7.0 mmHg SBP, -5.6 mmHg for DBP), this was counterbalanced by other findings. Upward slope of systolic pressure with age was 45% greater for the PRC than the other centres and 24% greater for diastolic pressure. As a result, although percentage hypertensive for ages 20-49 years for the PRC was half that in the 45 centres (6% vs. 12%), by age 50-59 years the prevalence was 31% in the PRC and 38% in the other centres. Hypertension prevalence in Tianjin, with highest Na/K in INTERSALT (7.6) was 40% for ages 50-59 years. While sample size in individual centres does not provide power to demonstrate aetiological relationships, these findings permit formulation of the following hypothesis: although lower body mass and lower alcohol intake may counteract to some degree impact of high salt intake, such intake over decades eventually takes its toll on BP.

[Experiences in improving prognosis of acute necrotizing pancreatitis]

Seventy-eight cases of acute necrotizing pancreatitis were analysed. Mortality varied with: timing of operation (14.3% after 5 days vs. 37.9% within 5 days), procedure (16.7% after necrosectomy vs. 44.4% after partial pancreatectomy) and nutritional support (15.0% with nutritional support vs. 50.0% without). Univariate (Chi-square test) and multivariate analyses (Logistic regression analysis showed correlation between each variable (timing of operation, procedure and nutritional support) and survival. It is felt that delayed necrosectomy with intraabdominal lavage, and early nutritional support may help to improve prognosis of this disease.

The all-in-one nutrient solution in parenteral nutrition

Dextrose, lipid emulsion, amino-acids, electrolytes, vitamins and trace elements were mixed in a well defined order to prepare 10 different total nutrient admixture solutions. The pH and osmolality of these solutions did not change significantly during 14 days of storage at 4 degrees C. Mean diameters of lipid particles on different occasions for the different solutions varied from 0.31 +/- 0.10 mum to 0.48 +/- 19 mum with 95% of particles less than 0.6 mum. Particles greater than 6 mum were not observed. Cultures were all negative. 243 patients received 5101 infusions of the admixture fluids. Patients on treatment for more than 1 week showed improved nitrogen balance. Serum transferrin and albumin were increased when treatment was ongoing for more than 2 weeks. No adverse reactions or abnormal laboratory findings were observed. One patient, with only duodenum and a part the colon left, has been maintained in good health for more than 55 months using this kind of nutritional support.

[The prehospital emergency cardiac care in patients with acute myocardial infarction]

In order to evaluate the current status of prehospital care of acute myocardial infarction (AMI) in this city, the clinical manifestations and the emergency cardiac care in prehospital phase in 210 patients were reviewed in the period from 1987 to 1988. Before admission to CCU, 45.7% of the patients had complications of severe cardiac arrhythmias or hemodynamic disturbances and 14.8% had cardiac arrests. The mortality during the first 4 weeks was 25.2%. Among 53 patients who died, 50.9% occurred before admission and 37.7% within 1 hour. One hundred and ten patients (52.4%) had prehospital care and, 4 of them provided by the City Emergency Center and others by the local clinics near by. The median time from the cardiac attack to the first medical care, hospital arrival and CCU admission was 2, 3.6 and 6.3 hours respectively. The management on the scene was not efficient and effective in many patients. The rate of successful resuscitation in patients who had cardiac arrest out of hospital was only 7.7%. We are impressed that the mortality of patients with AMI is mainly in the early stage after appearance of symptoms. The initiation of emergency cardiac care is very necessary. The current status of prehospital cardiac care needs to be improved immediately, some suggestions are made for this purpose.

[Hemodynamic study of a single oral dose of enalapril in patients with heart failure]

Clinical and hemodynamic studies were carried out for the purpose of evaluating the effects of enalapril in the treatment of chronic heart failure. Enalapril 10-20 mg was given once to 10 patients with moderate to severe congestive heart failure (coronary 6, hypertensive heart disease 2 and idiopathic congestive cardiomyopathy). Hemodynamic studies were done on the first day after drug administration and the same dose was maintained for 2 weeks. The results showed a decrease of mean BP of 18.29% (P less than 0.01), CVP 40.4% mPAP 23.9%, PCWP 41.2%, SVR 39.9% and PVR 41.3% respectively (P less than 0.001). Cardiac index increased 44.16% (P less than 0.001). The therapeutic action lasted more than 24 hours after a single dose. No further drop of BP was found weeks later, 6 patients in NYHA class III and 2 in class IV improved to class II. No severe side effects were found. The results showed that enalapril is well tolerated after a single dose and its therapeutic action lasts 2 weeks with improvement both in hemodynamics and subjective symptoms.

[Cyclic AMP levels in the plasma and ischemic myocardium and free fatty-acid levels in the serum following coronary artery ligation in dogs: relation to ventricular fibrillation]

This study was designed to shed light on the biochemical causes of serious ventricular arrhythmias in the early stage of acute myocardial infarction (AMI). Fourteen mongrel dogs were divided into 2 groups. One group was subjected to coronary ligation by placing silk sutures around the LAD coronary artery about 1.5 cm from its origin. All the dogs of this group were found to have ventricular tachycardia and fibrillation, starting approximately 18 min. After ligation, associated with regional accumulation of myocardial cAMP in the ischaemic zone. The increase of cAMP started about 10-15 min. before the onset of the arrhythmia. In contrast, the control group had only sutures placed without ligation and was not found to have change in myocardial cAMP within 35 min and arrhythmias at the same time. Both plasma cAMP and serum FFA were studied, but no significant changes were found. It is concluded that myocardial cAMP may play an important role in the genesis of ventricular arrhythmias in the acute ischaemic heart and it may be one of the arrhythmogenic factors to evoke ventricular arrhythmias.

A preliminary study on the therapeutic effects of a calcium antagonist (diltiazem) on primary congestive cardiomyopathy. A clinical survey of 15 cases

The clinical effects of diltiazem in 15 patients with congestive cardiomyopathy were observed. Symptoms were controlled in 66% and cardiac enlargement improved in 73.3%. There was a decrease in cardiac silhouette on X-ray in 18.82 +/- 3.2% (p less than 0.01), with an increase of EF(%), CO, CI and a decrease of TPR on two-dimensional (2-D) echocardiogram (p less than 0.01). Prior to treatment, the cardiac status of 8 cases was grade III and 7 cases grade IV; after treatment 1 case was grade I, 8 grade II, 5 grade III and 1 grade IV. This improvement might be due to the blockade of calcium channels and the fact that diltiazem has the least negative inotropic effect among the calcium antagonists. The dosage, route of administration, and prevention of side effects are discussed.

The relationship between cations and blood pressure in the People's Republic of China

Blood pressure was measured in the north and in the south of the People's Republic of China in 1002 men and 1006 women. The 24-hour urinary excretion of sodium, potassium, calcium, magnesium, and creatinine was measured, and the relationship between urinary cations and blood pressure was studied. Blood pressure and 24-hour sodium excretion were higher in northern China than in southern China. With some exceptions, a positive correlation was found between urinary sodium and blood pressure and a negative one between 24-hour urinary potassium excretion and blood pressure. Urinary calcium correlated negatively and urinary magnesium did not correlate significantly with blood pressure. The sodium/potassium ratio correlated positively with blood pressure, and the calcium/magnesium ratio, negatively. This study confirms the positive within-population relationship between sodium intake and blood pressure in Oriental populations.

Cardiac free wall rupture after acute myocardial infarction. Clinical and pathological analysis

Clinical and pathological findings in 15 autopsy cases, 13 males and 2 females, confirming cardiac free wall rupture after AMI were reported. The incidence is 30.6% of all autopsy cases of AMI in Chinese PLA General Hospital from 1958 to 1979. The ages ranged from 46 to 79 years, 10 being above 60 years. For 73.3% it was the first AMI and 66.7% of the patients had a history of hypertension. Thirteen of the 15 patients died within 5 days after the onset of AMI and another 2 within 7 days. When the cardiac rupture occurred, the ECG generally showed bradycardia, AV-junctional rhythm, III degrees AV block or isorhythmic ventricular rhythm and cardiac arrest. Both the gross and microscopic AMI were examined in 13 cases. All of them had a septal infarct, but only 2 had an ECG diagnosis. Of the 6 patients with inferior MI on ECG, 5 had right and left coronary lesions worse than grade III. The effective prevention of cardiac rupture consists of early diagnosis, control of chest pain and vomiting, prevention or treatment of hypertension or hypotension and 1 to 2 weeks of bed rest after the onset of AMI.

Serum lipids in the People's Republic of China. Comparison of Western and Eastern populations

Serum cholesterol and HDL cholesterol levels were measured in an urban and a rural population of the People's Republic of China and compared with cholesterol values obtained in Belgium and in the Republic of Korea, with use of the same methodology. Total cholesterol levels were markedly lower in the People's Republic of China than in Belgium and generally lower than in Korea, both in male and female subjects. However, the differences in HDL cholesterol levels among the three populations were small in males and only significantly higher in Belgium in the age classes below 34 years. In women of all age groups, HDL cholesterol values were significantly higher in Belgium than in China and Korea. Total cholesterol levels below 100 mg/dl were found in the People's Republic of China in about 2% of the participants. Apolipoprotein B was significantly lower, and the apolipoprotein A1/B ratio was significantly higher, in China and Korea compared to Belgium.