Intramedullary spinal tuberculomas during treatment of tuberculous meningitis

A case of multiple intramedullary spinal tuberculomas developing paradoxically during effective treatment of tuberculous meningitis is described. Serial MR imagings with Gd-DTPA enhancement studies showed initial homogeneous enhanced lesion representing myelitis or the early tuberculoma stage, which evolved to show ring enhancement with hypointense center later. Their appearance was similar to those described in brain tuberculoma. Gd-DTPA enhancement MR imaging is more sensitive than MR imaging without enhancement in demonstrating the lesions of tuberculoma and arachnoiditis. Antituberculous medication was effective with marked clinical improvement.

Apolipoproteins and ischaemic heart disease: implications for screening

Apolipoproteins and lipids are established risk factors of ischaemic heart disease (IHD) but their efficacy as screening tests is not known. We therefore examined the mortality from IHD and serum concentrations of lipids and apolipoproteins in a prospective study of 21,520 men aged 35-64 years. Serum apo B was the apolipoprotein most strongly associated with IHD risk; a decrease in apo B of 10% was associated with 22% lower risk of IHD. However, measurement of apo B alone detected only 17% of all IHD deaths at the cost of a 5% false-positive rate. Combining apo B with apo AI and apo (a) increased the detection rate to 19%. With systolic blood pressure, smoking, and family history of IHD the detection rate increased to 28%. We conclude that screening for IHD by measuring apo B alone or with apo AI and apo (a) is too poor to discriminate between recommending drug therapy or lifestyle change for some and not others. It is not advisable to screen for IHD by measuring any combination of cholesterol, apo B, apo AI, apo (a) and the other risk factors. The primary aim in prevention of ischaemic heart disease should be to lower the risk factors in the population.

The limits of template-directed synthesis with nucleoside-5'-phosphoro(2-methyl)imidazolides

In earlier work we have shown that C-rich templates containing isolated A, T or G residues and short oligo(G) sequences can be copied effectively using nucleoside-5'-phosphoro(2-methyl)imidazolides as substrates. We now show that isolated A or T residues within an oligo(G) sequence are a complete block to copying and that an isolated C residue is copied inefficiently. Replication is possible only if there are two complementary oligonucleotides each of which acts as a template to facilitate the synthesis of the other. We emphasize the severity of the problems that need to be overcome to make possible non-enzymatic replication in homogeneous aqueous solution. We conclude that an efficient catalyst was involved in the origin of polynucleotide replication.

Map-based cloning of a protein kinase gene conferring disease resistance in tomato

The Pto gene in tomato confers resistance to races of Pseudomonas syringae pv. tomato that carry the avirulence gene avrPto. A yeast artificial chromosome clone that spans the Pto region was identified and used to probe a leaf complementary DNA (cDNA) library. A cDNA clone was isolated that represents a gene family, at least six members of which genetically cosegregate with Pto. When susceptible tomato plants were transformed with a cDNA from this family, they were resistant to the pathogen. Analysis of the amino acid sequence revealed similarity to serine-threonine protein kinases, suggesting a role for Pto in a signal transduction pathway.

[Plasmid profiles of 120 strains of Pseudomonas aeruginosa]

The plasmid profiles of 120 clinical isolates of Pseudomonas Aeruginosa (PA) from Nanjing City were determined by the Kado and Liu method and the technique was compared with other epidemiological typing schemes based on serotype. Only 24.2% of these strains harbored plasmids. A total of 13 different plasmid profiles were observed. Plasmids varied in size from 1.91 to 45.14 MDa. The serotypability was 95.00%. A comparison between the plasmid profiles and the serotypes might be of value in the epidemiologic fingerprinting of clinical isolates of PA.

[The isolation and identification of a Clostridium botulinum serotype A strain]

319 soil specimens were collected from different places of China for isolating Clostridium botulinum. A strain of Clostridium botulinum was isolated from a culture of soil specimens in Ruoergai of Sichuan Province, the strain was called As-3. The As-3 was identified as Clostridium botulinum serotype A according to its biological properties, biochemical serological and toxicological characteristics and DNA determination. Its DNA G + C mol is 24.9%. The toxin produced by As-3 strain can only be neutralized by type A antiserum.

Differential diagnosis between fibrodysplasia ossificans progressiva and childhood dermatomyositis with calcinosis

Both fibrodysplasia ossificans progressiva (FOP) and childhood dermatomyositis with calcinosis are rare diseases, and present with ossifying or calcifying processes. Six cases of FOP and one case of childhood dermatomyositis with calcinosis are studied. All six FOP patients had the typical digital anomalies and the characteristic ectopic bone formation starting from the trunk. Calcification in the case of childhood dermatomyositis occurred in the limbs. A carefully differentiated diagnosis between these two diseases is needed, because they share common clinical and radiologic features, but require different management. Delay in the diagnosis of FOP is common, although early recognition of FOP prevents a child from accidental or iatrogenic injury, which can precipitate ectopic ossification. Surgical removal of the ectopic bone or release of the contracture in three FOP patients was followed by rapid recurrence. Entrapment neuropathy and a mild myopathic pattern in two FOP patients, who underwent nerve conduction and electromyographic studies, were secondary to ectopic bone formation. One FOP patient received a computed tomography examination which showed basal ganglia calcification. No coexistence of FOP and childhood dermatomyositis with calcinosis was found.

MRI and CT features of cerebellar degeneration

The many conventional classifications of cerebellar degeneration are usually based on information obtained in post-mortem examinations. On the other hand, neuroimagings, particularly with follow-up imaging studies, can demonstrate morphologic changes at various stages of disease evolution in living patients, thus providing a better understanding and evaluation of the disease processes, leading towards an earlier and more accurate diagnosis. Obviously, some patients require determination of a biochemical marker or markers in the final diagnosis. In Friedreich's ataxia, major changes are severe atrophy of the spinal cord with flattening of its posterior aspect. The medulla oblongata becomes smaller and the vermian and paravermian structures adjacent to the primary fissures become mildly atrophic. In hexosaminidase deficiency, there is pancerebellar atrophy with marked dilatation of the fourth ventricle. Cerebellar atrophy is more marked in the hemispheres than in the vermis, while the brain stem shows little change. The frontal and parietal sulci are usually slightly prominent. In cerebello-olivary atrophy (also called cortical cerebellar degeneration), there is atrophy of the superior vermis, especially the declive, folium and tuber. There is also atrophy of the lateral part of the cerebellar hemispheres, giving an appearance of the "fish-mouth deformity" on parasagittal sections. The fourth ventricle may be greatly enlarged. In dominant olivopontocerebellar atrophy (OPCA), the Menzel type is characterized by cerebellar atrophy of the "fine comb" type with the greatest involvement in the anterior lobe and in the upper part of the middle lobe. The hemispheres are more involved than the vermis. The brainstem, especially the pons, and the brachia pontis are also atrophic. In severe cases, the changes are very marked. Although the fourth ventricle is large, it lacks the ballooning characteristic of OPCA with slow saccades. In OPCA with slow saccades with or without retinal degeneration, the most pathognomonic features are "ballooning of the fourth ventricle" due to excavation of its floor and the "molar tooth deformity" secondary to severe atrophy of the pons, brachia pontis and conjunctiva. The cerebellum usually shows pancerebellar atrophy of the "fine comb" type. In recessive OPCA, cerebellar atrophy is most marked in the lateral part of the cerebellar hemispheres with "fish mouth deformity" secondary to drop-out of the tertiary and secondary folia from the primary folia. This feature is less marked in cases of atypical cerebello-olivary atrophy. In late-onset sporadic OPCA with autonomic failure, the cerebellum, especially its lateral portions and the brainstem, are variably involved in the atrophic processes, ranging from very mild to severe involvement.(ABSTRACT TRUNCATED AT 250 WORDS)

Spectral measurements of NH(3) absorption lines by a 1.5-microm grating-external-cavity semiconductor laser

Forty-four NH(3) absorption spectral lines of the combination tones of the vibration-rotation transitions were observed at 1.4988-1.5520 microm with a 1.5-microm grating-external-cavity semiconductor laser. The linewidth and absorption rate of NH(3) absorption spectral lines were measured. Also, the changes of center frequency and linewidth of the NH(3) absorption spectral line with the our knowledge the first time.

Production of eicosanoids in response to endothelin-1 and identification of specific endothelin-1 binding sites in airway epithelial cells

The effect of endothelin-1 (ET-1) on arachidonate metabolism in the respiratory epithelium was investigated in primary cultures of feline tracheal epithelial cells. Subconfluent epithelial cell cultures were stimulated by ET-1, and eicosanoid generation was determined by high performance liquid chromatography (HLPC) of 3H-labeled arachidonic acid (AA) metabolites and by radioimmunoassay (RIA) of corresponding nonradiolabeled HPLC elution. The HPLC chromatograms of [3H]AA-prelabeled samples revealed that ET-1 (10(-5) M) augmented the release of prostaglandin (PG) E2, 12-hydroxyeicosatetraenoic acid (HETE), PGF2 alpha, and AA. RIA of corresponding nonradiolabeled HPLC elution demonstrated a significantly increased release of PGE2, PGF2 alpha, and 12-HETE as well as 5-HETE in response to ET-1 stimulation. 5-HETE release from ET-1-stimulated cells was further identified by gas chromatography/mass spectrometry (GC/MS). The stimulating effect of ET-1 on AA metabolism was dose dependent (10(-5) to 10(-7) M) and peaked within 1 h with a progressive decline over the subsequent hours. Using 125I-labeled ET-1 as radioligand, the presence of specific binding sites for ET-1 was demonstrated in cultured feline tracheal epithelial cells. ET-1 binding reached equilibrium within 1 h at 37 degrees C. Scatchard analysis suggested the existence of two saturable binding sites, with the estimated equilibrium dissociation constant (Kd) of 35.3 pM and maximal binding capacity (Bmax) of 15.0 fmol/10(7) cells for the higher affinity binding site and Kd of 205.9 pM and Bmax of 35.0 fmol/10(7) cells for the lower affinity binding site.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonenzymatic template-directed synthesis on hairpin oligonucleotides. 3. Incorporation of adenosine and uridine residues

We have used [32P]-labeled hairpin oligonucleotides to study template-directed synthesis on templates containing one or more A or T residues within a run of C residues. When nucleoside-5'-phosphoro(2-methyl)imidazolides are used as substrates, isolated A and T residues function efficiently in facilitating the incorporation of U and A, respectively. The reactions are regiospecific, producing mainly 3'-5'-phosphodiester bonds. Pairs of consecutive non-C residues are copied much less efficiently. Limited synthesis of CA and AC sequences on templates containing TG and GT sequences was observed along with some synthesis of the AA sequences on templates containing TT sequences. The other dimer sequences investigated, AA, AG, GA, TA, and AT, could not be copied. If A is absent from the reaction mixture, misincorporation of G residues is a significant reaction on templates containing an isolated T residue or two consecutive T residues. However, if both A and G are present, A is incorporated to a much greater extent than G. We believe that wobble-pairing between T and G is responsible for misincorporation when only G is present.

Effects of exogenous gamma-aminobutyric acid on experimental arrhythmias

The effects of exogenous gamma-aminobutyric acid (GABA) 10 mg.kg-1 iv in preventing arrhythmias induced by drugs and ischemia were studied in mice, rats, and guinea pigs. It was found that the threshold dose of aconitine inducing arrhythmia in mice and the recovery rate to normal sinus rhythm increased significantly, ED50 of GABA was 5.4-5.8 mg.kg-1. The duration of ventricular tachycardia (VT) induced by aconitine in rats was shortened (P < 0.01). The incidence and the mortality of ventricular fibrillation (VF) in GABA group were decreased to 0/10 vs 6/10 and 5/10 in control, respectively (P < 0.05). The doses of ouabain to induce ectopic beats (EB), VT, VF, and cardiac arrest (CA) in guinea pigs were increased (P < 0.01). The incidence of VF induced by coronary artery ligation in rats was decreased to 0/5 in GABA group vs 4/5 in control group (P < 0.01). The total amount of EB, total time of VT, and VF were 66%, 41%, and 0% of the control group, respectively. The anti-arrhythmic effects of GABA were dose-dependent and as potent as procainamide (10 or 5 mg.kg-1, iv). The results suggest GABA (10 mg.kg-1, iv) may be useful for the prevention of VT and VF.

Experimental Trichosporon infection in persistently granulocytopenic rabbits: implications for pathogenesis, diagnosis, and treatment of an emerging opportunistic mycosis

Disseminated Trichosporon infection, an uncommon but emerging opportunistic mycosis due to Trichosporon beigelii, is frequently difficult to diagnose, refractory to treatment, and associated with a high attributable mortality. Models of disseminated and gastrointestinal Trichosporon infection were developed in persistently granulocytopenic rabbits. The patterns of infection resembled those of clinical disease, including cutaneous lesions, chorioretinitis, renal infection, pulmonary infection, and antigenemia cross-reactive with cryptococcal capsular polysaccharide. Antigenemia, an early manifestation of disseminated Trichosporon infection, originated in vivo from a fibrillar extracellular matrix. Trichosporon organisms disseminated from the gastrointestinal tract to visceral tissue in colonized immunosuppressed rabbits, whereas there was no dissemination from the gastrointestinal tract of otherwise normal rabbits. The antifungal triazoles, fluconazole and SCH 39304, were most active; maximum tolerated doses of amphotericin B and liposomal amphotericin B were ineffective. Trichosporon antigenemia declined in response to antifungal therapy. These findings contribute to improved understanding of the pathogenesis, diagnosis, and treatment of disseminated Trichosporon infection.

A novel repetitive DNA sequence in the genus Oryza

Repetitive DNA sequences in the genus Oryza (rice) represent a large fraction of the nuclear DNA. The isolation and characterization of major repetitive DNA sequences will lead to a better understanding of rice genome organization and evolution. Here we report the characterization of a novel repetitive sequence, CC-1, from the CC genome. This repetitive sequence is present as long tandem arrays with a repeat unit 194 bp in length in the CC-diploid genome but 172 bp in length in the BBCC and CCDD tetraploid genomes. This repetitive sequence is also present, though at lower copy numbers, in the AA and BB genomes, but is absent in the EE and FF genomes. Hybridization experiments revealed considerable differences both in copy numbers and in restriction fragment patterns of CC-1 both between and within rice species. The results support the hypothesis that the CC genome is more closely related to the AA genome than to the BB genome, and most distantly related to the EE and FF genomes.

Airway epithelial cell mucin release: immunologic quantitation and response to platelet-activating factor

Mucus production is an integral component of airway mucosal inflammation. Platelet-activating factor (PAF) is a phospholipid mediator implicated in the pathogenesis of many inflammatory processes, including airway inflammation. PAF functions as a mucus secretagogue when mucus is quantitated as radiolabeled glycoconjugates released from airway organ cultures. To more directly assess the interaction of PAF and airway epithelial mucous cell secretion, we used primary feline tracheal epithelial cell cultures and an immunoassay for a specific mucous cell secretory vesicle component. Cultured tracheal epithelial cells were shown to synthesize and secrete glycoconjugates with mucin characteristics. These mucin-type glycoconjugates were immunoreactive with a mucous cell-specific antibody. Localization of this antibody to components of the secretory vesicles of cultured epithelial cells was confirmed by electron microscopic immunogold labeling. Using this monoclonal antibody, an immunoassay was developed to quantitate release of immunoreactive material into cell culture media. Exposure of cultures to PAF produced a concentration-dependent, prompt release of immunoreactive material. Concentration-dependent inhibition of this effect was demonstrated by coincubation with the PAF receptor antagonists, WEB 2086 and Ro 19-3704. A component of the signal transduction pathway for PAF effects was studied in cultured tracheal epithelial cells by coincubation of PAF with nordihydroguaiaretic acid (NDGA), a combined lipoxygenase and cyclooxygenase inhibitor, or p-bromophenacyl bromide (BPB), an inhibitor of cellular arachidonic acid release. Both NDGA and BPB blocked PAF-stimulated mucin release in a concentration-dependent manner. These studies demonstrate a direct airway epithelial mucous cell secretagogue effect that appears to be dependent upon airway epithelial PAF receptors and altered cellular lipid metabolism. These findings suggest a direct and potent mechanism for goblet cell secretion during airway inflammation.

Endothelin-1 stimulates eicosanoid production in cultured human nasal mucosa

Endothelin (ET) has been shown to contract both vascular and nonvascular smooth muscle and to stimulate human nasal glandular secretion of serous and mucous cell products. Some effects of ET are thought to be mediated by eicosanoid production. To explore the direct effect of ET on arachidonate metabolism in cultured human nasal mucosal explants, eicosanoids were measured after ET-1 stimulation. After labeling the explants with [3H]arachidonic acid (AA), supernatant from control and ET-1-treated explants were fractionated by reverse-phase high-performance liquid chromatography (HPLC). The resulting elution pattern suggested the release of prostaglandin (PG) E2 and AA in response to ET-1 stimulation. Radioimmunoassay after HPLC resolution confirmed that ET-1 induced a significantly increased release of PGE2 as well as PGD2, PGF2 alpha, thromboxane B2, and 15-hydroxyeicosatetraenoic acid (15-HETE). Although significant amounts of 15-HETE were generated, cyclooxygenase product generation was most remarkable. Eicosanoid release after ET-1 exposure (10 to 0.1 microM) is concentration dependent and occurs within 1 h. Whereas 15-HETE release was maximal at 4 h, prostanoid production was maximal 1 h after exposure to ET-1. Other assayed AA metabolites, including the peptidoleukotrienes, did not significantly change after ET-1 stimulation. We conclude that ET-1 induces the release of predominantly cyclooxygenase products from cultured human nasal mucosal explants.

[Influence of neural regulation on anti-arrhythmic effects of GABA in rats]

In anesthetized rats, GABA 10 mg.kg-1 iv delayed the onset of ventricular premature (VP) (P less than 0.01) and ventricular tachycardia (VT) (P less than 0.01) and reduced the incidence of ventricular fibrillation (VF) (P less than 0.05). The anti-arrhythmic effects of GABA remained after cervical vagotomy, iv hexamethonium 10 mg.kg-1 or destruction of CNS. It was also seen on pithed rats. In Langendorff heart, GABA 100 mg.L-1 elevated the threshold doses of aconitine required to induce VT (P less than 0.01), VF (P less than 0.01), and heart stop (HS) (P less than 0.01). These results suggest that iv GABA counteracts aconitine-induced arrhythmia directly on the heart, not related to the neural regulation.

Effect of protein kinase C activating agents on respiratory glycoconjugate release from feline airways

Abnormal regulation of airway glycoprotein secretion may underlie many respiratory diseases. Experimental activation of the protein kinase C (PKC) family of cytosolic enzymes has been shown to induce a secretory response in many tissues. To estimate the effect of PKC activation on airway secretion, alteration in the amount of radiolabeled respiratory glycoconjugate (RGC) released into culture media was determined following feline airway explant exposure to PKC activating agents. Exposure to two known activators of PKC, phorbol 12-myristate 13-acetate (PMA) and mezerein (MEZ), resulted in profound increases in respiratory glycoconjugate release over a seven day experimental period. The response evolved over several hours and was dose dependent. Maximal RGC release, 90% above control, occurred 2 days after exposure to either PMA or MEZ. Pharmacological inhibition of the PKC effect using two PKC inhibitors, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine and sphingosine, resulted in dose-dependent antagonism of the maximal PMA (10(-7) M)-stimulated RGC release, suggesting altered PKC activity was responsible for augmenting RGC release. Since altered arachidonic acid metabolism has been implicated in mediating some PKC effects, eicosanoids were assayed in airway explant supernatants following PMA exposure. Enhanced release of both cyclooxygenase and lipoxygenase pathway products was detected by radioimmunoassay. Cotreatment of explants with PMA and an inhibitor of oxidative arachidonic acid metabolism, nordihydroguaiaretic acid, blocked RGC release. These data demonstrate prolonged augmentation of respiratory glycoconjugate release from airway explants following exposure to PKC-activating agents.

Platelet-activating factor stimulates eicosanoid production in cultured feline tracheal explants

Eicosanoids have been shown to be major mediators of airway inflammation. Platelet-activating factor (PAF), a potent bronchoconstrictor and stimulator of respiratory mucous secretion, may mediate some of its effects via eicosanoid production. To explore eicosanoid generation by cultured feline tracheal explants, eicosanoids were measured following PAF stimulation. After labeling the explants with [3H]arachidonic acid, supernatant from control and PAF treated explants was fractionated by reverse phase high-performance liquid chromatography (HPLC). The resulting elution pattern suggested the release of arachidonic acid (AA), 15-hydroxyeicosatetraenoic acid (HETE), leukotriene (LT)B4, C4, prostaglandin (PG) D2/E2/F2 alpha, and 6-keto-PGF1 alpha. Radioimmunoassay (RIA) following HPLC resolution confirmed that PAF induced a significantly increased release of peptido-leukotrienes, PGD2, PGE2, PGF2 alpha, LTB4, and 5-HETE, as well as thromboxane (TX) B2. The most remarkable increase was LTC4/D4/E4 (15 x control) and PGD2 (4 x control). The PAF antagonist Ro 19-3704 had an inhibitory effect on the PAF-stimulated release of peptido-leukotrienes. We conclude that PAF stimulates the production of a variety of lipoxygenase and cyclooxygenase pathway metabolites in feline airways.

[A new resinifying solution without the effect of discoloring teeth]

In order to solve the problem of tooth stain caused by phenolformaldehyde resinifying therapy, we have, on basis of theory of the resinifying therapy, prepared a colourless resinifying solution RF-109. Experiments on its chemical and physical properties, ability of becteriostasis, animal tissues reaction including ultra-structure observation after resinified muscles of rats, rabbits and dogs as well as imitate root canal filling have been performed. Results proved that RF-109 is desirable for resinifying therapy. Its peculiarity is that after pulp therapy, the tooth will not be stained. And besides, it is much simpler in preparation, and lower in cost than that of phenol-aldehyde resin. Its preservation is also much easier. The long-term results of RF-109 is satisfactory in 91.30% of 174 cases followed-up for three years.

Leptotrichia buccalis bacteremia in patients with cancer: report of four cases and review

Leptotrichia buccalis, an anaerobic gram-negative rod, is part of the normal oral flora and has rarely been isolated from clinical material. We describe four patients with neutropenia and progressive malignancy who had symptomatic L. buccalis bacteremia, and we review an additional four cases from the literature. The mean age of the patients was 31 years (range, 7-73 years), with an equal number of males and females. The number of positive blood cultures in each case ranged from one to four (mean, two); these cultures became positive after 48-120 hours (median, 54 hours). All tested isolates were sensitive to the beta-lactam agents, clindamycin, tetracycline, and metronidazole; five of seven were sensitive to chloramphenicol; and not one was sensitive to the aminoglycosides, vancomycin, ciprofloxacin, or erythromycin. Seven patients had one or more possible portals of entry for bacteremia, including mucositis (four patients), mucositis plus esophageal lesions (two), and possible mucositis plus diverticulitis (one). L. buccalis should be considered a potential pathogen in neutropenic patients, especially when breaks in the mucosal breaks in the mucosal barriers are present.

[Determination of berberine hydrochloride in traditional Chinese medicines containing Coptis chinensis Franch by reversed phase high performance liquid chromatography]

This paper reports a reversed phase high performance liquid chromatography method to determine berberine hydrochloride in Coptis chinensis Franch and in the traditional Chinese medicine containing Coptis chinensis Franch. The result shows that the mobile phase of 0.4mol/L ammonium nitratemethanol (52:48) can give a satisfactory separation. The extraction of sample with 1% H2SO4 solution using the ultrasonic vibration method is simple and easy to operate.

Duration of immunity following immunization with live measles vaccine: 15 years of observation in Zhejiang Province, China

The duration of immunity following measles vaccination of 2882 immunized children has been investigated in a closed region of China for 15 years. A total of 1002 of the children were treated as primary immunization subjects, and 1547 as reimmunization subjects. These two cohorts were not in contact with known wild measles virus over the whole observation period, and the results obtained probably reflected the antibody responses to measles vaccine alone. The remaining 333 vaccinees came into contact with wild measles virus, and this permitted evaluation of the protective effect of the measles vaccines tested: 4 children experienced very mild clinical measles, and 329 experienced subclinical infection, including 12 who had had undetectable haemagglutination-inhibition antibodies for 9-10 years. These results indicate that the immunity induced by successful primary immunization may persist for at least 15 years. Within this period, a second dose of vaccine only induces low antibody responses which decrease rapidly to their original levels. This provides strong evidence that the immunity produced by primary immunization is long-lasting. However, there were some indications that reimmunization might produce better effects if live attenuated measles virus were used with a longer interval between doses.

[Changes in cardiac function at rest and during exercise in mountaineers at an extreme altitude]

At extreme altitude of 5,620 m, cardiac function was examined with electrical impedance at rest and during exercise. Mountaineers as subjects of experiment were divided into two groups: 15 subjects were Tibetan natives, and 10 subjects were Han visitors of expedition (both were young healthy males). The results showed that no significant difference was seen between the two groups in cardiac pump function at rest. In the Han visitors during exercise, HR increase was restricted, SV and CO were decreased, and PEP/LVET ratio was increased. In the Tibetan natives, HR increased gradually with increased work load, SV tended to be stable CO increased significantly under higher work load, and PEP/LVET ratio decreased gradually. These results suggest that the Tibetan natives were adapted to hypoxic environment much better than the immigrants because their cardiac reserve capacity and maximal oxygen uptake were better than the immigrants at extreme altitude.