Hypoxic ventilatory responsiveness in Tibetan compared with Han residents of 3,658 m

Lifelong high-altitude residents of North and South America acquire blunted hypoxic ventilatory responses and exhibit decreased ventilation compared with acclimatized newcomers. The ventilatory characteristics of Himalayan high-altitude residents are of interest in the light of their reportedly lower hemoglobin levels and legendary exercise performance. Until recently, Sherpas have been the only Himalayan population available for study. To determine whether Tibetans exhibited levels of ventilation and hypoxic ventilatory drives that were as great as acclimatized newcomers, we compared 27 lifelong Tibetan residents of Lhasa, Tibet, China (3,658 m) with 30 acclimatized Han ("Chinese") newcomers matched for age, body size, and extent of exercise training. During room air breathing, minute ventilation was greater in the Tibetan than in the Han young men because of an increased respiratory frequency, but arterial O2 saturation and end-tidal PCO2 did not differ, indicating similar levels of effective alveolar ventilation. The Tibetan subjects had higher hypoxic ventilatory response shape parameter A values and hypercapnic ventilatory responsiveness than the Han subjects. Among the Han subjects, duration of high-altitude residence correlated with the degree of blunting of the hypoxic ventilatory drive. Paradoxically, hyperoxia (inspired O2 fraction 0.70) increased minute ventilation and decreased end-tidal PCO2 in the Tibetan but not in the Han men. We concluded that lifelong Tibetan residents of high altitude neither hypoventilated nor exhibited blunted hypoxic ventilatory responses compared with acclimatized Han newcomers, suggesting that the effects of lifelong high-altitude residence on ventilation and ventilatory response to hypoxia differ in Tibetan compared with other high-altitude populations.     

Effect of chronic resistive loading on hypoxic ventilatory responsiveness

Depression of ventilation mediated by endogenous opioids has been observed acutely after resistive airway loading. We evaluated the effects of chronically increased airway resistance on hypoxic ventilatory responsiveness shortly after load imposition and 6 wk later. A circumferential tracheal band was placed in 200-g rats, tripling tracheal resistance. Sham surgery was performed in controls. Ventilation and the ventilatory response to hypoxia were measured by using barometric plethysmography at 2 days and 6 wk postsurgery in unanesthetized rats during exposure to room air and to 12% O2-5% CO2-balance N2. Trials were performed with and without naloxone (1 mg/kg i.p.). Room air arterial blood gases demonstrated hypercapnia with normoxia in obstructed rats at 2 days and 6 wk postsurgery. During hypoxia, a 30-Torr fall in PO2 occurred with no change in PCO2. Hypoxic ventilatory responsiveness was suppressed in obstructed rats at 2 days postloading. Naloxone partially reversed this suppression. However, hypoxic responsiveness at 6 wk was not different from control levels. Naloxone had a small effect on ventilatory pattern at this time with no overall effect on hypoxic responsiveness. This was in contrast to previously demonstrated long-term suppression of CO2 sensitivity in this model, which was partially reversible by naloxone only during the immediate period after load imposition. Endogenous opioids apparently modulate ventilatory control acutely after load imposition. Their effect wanes with time despite persistence of depressed CO2 sensitivity.     

Metabolism and acid-base status during hypoxic ventilatory depression

In the present study, leukocyte DNA from 143 patients with familial clustering of breast and/or ovarian cancer and tumour DNA from 96 breast carcinomas were screened for base mutations in the estrogen receptor gene (ESR). Three patients with a family history of cancer were carrying a Gly160Cys germline substitution. This alteration was also detected in eight (four females and four males) of 729 controls (366 female, 363 males), indicating that the substitution probably represents a polymorphism. However, in the 229 female controls in whom family history of cancer was known, one of two who had a sister with breast cancer was carrying the variant allele. Hence, a possible clinical significance of the glycine into cysteine cannot be completely ruled out and should be further investigated. Somatic mutations were not detected in any of the tumours studied, and the present data do not provide support for somatic ESR base mutations as an important mechanism for hormonal therapy resistance in estrogen receptor-positive breast carcinomas.     

Prematurity alters hypoxic and hypercapnic ventilatory responses in developing lambs

We have determined the effects of preterm birth on the postnatal development of ventilatory responses to progressive hypoxia and hypercapnia in awake lambs. Hypoxic and hypercapnic rebreathing tests were performed at weekly intervals in 5 preterm (born at 135 +/- 0.5 d) and 5 term (born at 146 +/- 0.2 d) lambs up to 6-7 weeks after birth. Term lambs were also studied at 25 weeks after birth. During rebreathing tests, we measured arterial PO2 and PCO2 and related them to minute ventilation (VI). Owing to variability in resting PAO2, hypoxic sensitivity was defined as the percentage increase in VI when PaO2 fell to 60% of resting values. Hypoxic sensitivities of preterm lambs did not change with age (68.9 +/- 24.4%), whereas values for term lambs more than doubled over the first 6 weeks (day 2, 73.9 +/- 15.8%; week 6, 227.4 +/- 24.9%) but returned to early postnatal values by week 25 (87.0 +/- 21.2%). Hypercapnic sensitivities (ml min-1 kg-1 mmHg CO2(-1) of preterm lambs were lower than those of term lambs between day 2 and week 2, but reached values in term lambs thereafter. We conclude that preterm birth abolishes the normal postnatal maturation of hypoxic ventilatory sensitivity, and temporarily depresses hypercapnic sensitivity.     

A new aspect of the carotid body function controlling hypoxic ventilatory decline in humans

Ventilatory response to eucapnic sustained mild hypoxia was measured in one patient with unilateral and three patients with bilateral carotid body (CB) resection (defined UR and BR, respectively). The profile of ventilatory response in UR patient was initially augmented then gradually declined (biphasic pattern) as generally seen in normal subjects although the absolute magnitude was substantially low. On the other hand, biphasic pattern was disappeared in all three BRs. Lack of hypoxic ventilatory decline (HVD) in the late period of sustained hypoxia was in marked contrast to that reported in the anaesthetized and CB-denervated animals whose ventilation was severely depressed lower than the pre-hypoxic control level. In view of recent knowledge that the analogous mild hypoxia in normal animals and humans elicits an useful adaptation to economize energy expenditure with maintaining reversible excitability in control of respiration, BR patients were considered to have lost this ability. We conclude that in awake humans the CB not only stimulates ventilation but also controls the degree of subsequent HVD during sustained hypoxia.     

Long-lasting treatment with adenosine receptor antagonists: effects on hypoxic tolerance and vascular responsiveness

In electrically driven myocardial preparations obtained from chronically methylxanthine-[aminophylline (APH) and 8-phenyltheophylline (8-PT)] or solvent(DMSO)-treated guinea pigs no differences were found in alteration of mechanical activity under hypoxia and reoxygenation. The vasoconstrictor effects observed after in vitro exposure of pulmonary arterial preparations (excised from either methylxanthine- or solvent-treated guinea pigs) to both noradrenaline and PGF2 alpha were also similar. In methylxanthine-treated vascular tissues, however, nitroglycerin and NO exerted more pronounced vasorelaxant effect than in specimens prepared from solvent-treated guinea pigs.     

Unilateral bronchography at a young age and ventilatory function

In 21 males, aged about 20, 18 out of them with chronic bronchopulmonary diseases (bronchiectases, focal fibrosis, deforming bronchitis) and three healthy--VC, FEFR1, FVC, MMV50, MEFR200-1200, MAEFR, MAEFR25-75 and MEFR50 and MEFR90 were spirographically investigated prior to, two hours afert and 24 hours after unilateral bronchography; the three of the investigations were combined with a subsequent inhalation bronchodilatation test with orziprenalin--aersol (alupent). A mixed (restrictive-obstructive) ventilation syndrome with bronchospasm was established to develop after the bronchography. The restrictive syndrome is prevailing and that is conditioned by the absence of a definite manifestation of the obstruction at the level of the flow rates with small pulmonary volmes. The restrictive syndrome is admitted to be conditioned by "fear of coughing and the obstructuve-by the opaque medium and bronchospasm after the injection of the opaque substance.     

Modulation of the hypoxic ventilatory response by Ca2+-dependent and Ca2+-independent protein kinase C in the dorsocaudal brainstem of conscious rats

Over the last decade, nursing in the United Kingdom has witnessed a major development and expansion in the number of Clinical Nurse Specialists. These nurses are considered to be experts in their own specialities, have in-depth knowledge and provide a service for patients, relatives and staff. There is, however, a paucity of literature relating to role transition from experienced Staff Nurse to Clinical Nurse Specialist. Using Nicholson's (1984) model of work-role transition and Wanous' (1992) four-stage model of organizational socialization, this study explores the transition of two nurses from experienced Staff Nurses to novice Clinical Nurse Specialists.     

莱钢1880m^3高炉稳定高效生产实践

通过对莱钢两座1880m^3高炉从投产到实现高效顺行的实践进行学法,提出原料、操作、设备管理等几个方面是实现高炉稳定高效顺行的重要因素。     

Reduced performance of male and female athletes at 580 m altitude

Patients with craniocervical mandibular (TMD) disorders can present with tinnitus as a primary or secondary complaint. The embryology and functional anatomy of the middle ear, temporomandibular joint, muscles of mastication and associated tendons, ligaments, blood vessels, nerves and lymphatics was found to be helpful in establishing etiologic concepts which relate tinnitus to these temporomandibular disorders. In addition to etiologic concepts, treatment modalities are described. The authors relate their experiences as well as those of others with different patient populations.     

安钢2200 m3高炉开炉与达产实践

对安钢2200m^3高炉开炉及达产的生产操作经验进行了总结。安钢2200m^3高炉采用PW串罐无料钟炉顶、铜冷却壁、联合软水密闭循环系统、“陶瓷杯”＋水冷炭砖薄炉底炉缸结构、INBA炉渣处理系统、3座改进型高温长寿内燃式热风炉、环形缝隙洗涤塔煤气清洗工艺等多项新技术、新设备。在开炉生产中,由于选择合适的开炉料,采用全焦开炉,制定合理的操作制度,操作调剂得当,实现了顺利开炉和快速达产。     

Skeletal muscle chemoreflex and pHi in exercise ventilatory control

To determine whether skeletal muscle hydrogen ion mediates ventilatory drive in humans during exercise, 12 healthy subjects performed three bouts of isotonic submaximal quadriceps exercise on each of 2 days in a 1.5-T magnet for 31P-magnetic resonance spectroscopy (31P-MRS). Bilateral lower extremity positive pressure cuffs were inflated to 45 Torr during exercise (BLPPex) or recovery (BLPPrec) in a randomized order to accentuate a muscle chemoreflex. Simultaneous measurements were made of breath-by-breath expired gases and minute ventilation, arterialized venous blood, and by 31P-MRS of the vastus medialis, acquired from the average of 12 radio-frequency pulses at a repetition time of 2.5 s. With BLPPex, end-exercise minute ventilation was higher (53.3 +/- 3.8 vs. 37.3 +/- 2.2 l/min; P < 0.0001), arterialized PCO2 lower (33 +/- 1 vs. 36 +/- 1 Torr; P = 0.0009), and quadriceps intracellular pH (pHi) more acid (6.44 +/- 0.07 vs. 6.62 +/- 0.07; P = 0.004), compared with BLPPrec. Blood lactate was modestly increased with BLPPex but without a change in arterialized pH. For each subject, pHi was linearly related to minute ventilation during exercise but not to arterialized pH. These data suggest that skeletal muscle hydrogen ion contributes to the exercise ventilatory response.     

2000m3高炉设计与生产实践

邯钢2000m^3高炉是在引进德国二手设备的基础之上建造而成的。该高炉原有效容积1858m^3,改进后高炉有效容积2000m^3。采用了槽下过筛,焦丁与烧结矿混装入炉,无料钟炉顶,软水闭路循环和薄壁炉衬的长寿炉体,双预热热风炉,底滤法水冲渣,富氧大喷吹,高炉煤气燃气轮机鼓风机,比绍夫煤气清洗系统,高炉煤气炉顶余压发电,计算机自动控制等先进技术。投产近4年来,各项指标均达到和超过了设计水平。     

宝钢5 m宽厚板轧机工艺装备及试生产实践

为满足中国造船工业的发展及石油天然气输送管道建设大量高等级宽厚板的需求,宝钢决定建设5 m宽厚板轧机.该轧机采用了高性能设备参数,采用计算机控制,一期建设1架精轧机,设计年产量140万t,现在已顺利实现月达产.介绍了该宽厚板轧机平面布置、生产工艺,并论述了所采用的技术,包括控轧控冷(TMCP)技术、厚度控制技术、平面形状控制技术、板形控制技术,同时介绍了热负荷调试进程及试生产结果.     

Neuromodulators and hypoxic hypothermia in the rat

We report the cloning of the mouse ortholog of the human GPR37 gene, which encodes an orphan G-protein-coupled receptor highly expressed in brain tissues and homologous to neuropeptide-specific receptors (D. Marazziti et al., 1997, Genomics 45: 68-77; Z. Zeng et al., 1997, Biochem. Biophys. Res. Commun. 233: 559-567). The genomic organization of the GPR37 gene is conserved in both mouse and human species with a single intron interrupting the receptor-coding sequence within the presumed third transmembrane domain. Comparative genetic mapping of the GPR37 gene showed that it maps to a conserved chromosomal segment on proximal mouse chromosome 6 and human chromosome 7q31. The mouse Gpr37 gene contains an open reading frame coding for a 600-amino-acid protein 83% identical to the human GPR37 gene product. The predicted mouse GPR37 protein contains seven putative hydrophobic transmembrane domains, as well as a long (249 amino acid residues), arginine- and proline-rich amino-terminal extracellular domain, which is also a distinctive feature of the human GPR37 receptor. Northern blot analysis of mouse tissues with Gpr37-specific probes revealed a main 3.8-kb mRNA and a much less abundant 8-kb mRNA, both expressed in the brain. A 3-kb mRNA is also expressed in the testis. Both the mouse and the human GPR37 genes may belong to a class of highly conserved mammalian genes encoding a novel type of G-protein-coupled receptor predominantly expressed in the brain.     

Exercise-related ventilatory abnormalities and survival in congestive heart failure

This retrospective study of 104 New York Heart Association class 1 to 4 heart failure patients undergoing exercise stress testing with gas exchange analysis demonstrated that the ventilatory equivalent for carbon dioxide at anaerobic threshold is useful in determining prognosis in patients with severe congestive heart failure, particularly when used in combination with peak exercise oxygen consumption. A ventilatory equivalent for carbon dioxide >50 and peak oxygen consumption < or =15.0 ml/kg/min defines a very high-risk patient group who should be prioritized for transplantation.     

Intellectuality and emotionality in psychiatric residents

The fully trained psychiatrist must be able to integrate vast amounts of phenomenological data as well as to empathically share feeling states in patients. Beginning psychiatric residents often lean either towards intellectuality or towards emotionality, tendencies which potentially reinforce splitting within the profession. Cognitive styles may correlate with neurophysiological indicators, such as hemispheric dominance and the augmenting-reducing dimension. There may also be sex differences in cognition; if so, they would have to be taken into account as more women enter psychiatric training. A theoretical understanding of individual differences in students provides a basis for the pedagogical correction of biases. Overly intellectual residents may be organically or psychodynamically oriented. In either case they favour theory over concrete experience, and there are difficulties in mobilizing their empathic capacities. Identification with empathic teachers and a focus in supervision on the perception and integration of more stimuli, especially nonverbal cues, are important correctives. Overly emotional residents identify excessively with their patients and tend to have problems with boundaries. An augmenting tendency, leading to stimulus overload, can be controlled by teaching residents how to structure and set limits. Identification with the supervisor is sided by clear boundaries in the supervisory relationship. In both cases the resident's strengths must not be denigrated while correcting his weaknesses. Examples of learning problems in both kinds of residents are given, with discussion of supervisory pitfalls.