摘要:

Hypertrophy of the left ventricle occurs in some but not all hypertensive patients. The present study was designed to examine the office and the 24-hour arterial pressure (AP) and heart rate (HR) recordings, and the AP response to physical stress in two age- and sex-matched hypertensive groups who differed in their left-ventricular mass (LVM). In addition, we tried to determine whether AP and HR measured at rest, under stress, or with 24-hour AP monitoring correlate with LVM. Ten hypertensive subjects with left-ventricular hypertrophy (LVH) made up the study group and 10 hypertensive subjects without LVH made up the control group. Anti-hypertensive medication was withdrawn at least four weeks prior to evaluation. The mean office AP measured during the washout period was 157 ± 13/100 ± 11 mm Hg in the study group and 157 ± 17/104 ± 7 mm Hg in the control group. However, 24-hour AP monitoring disclosed that the study group had significantly higher AP than the control group during both day and night. The control group had a significantly faster HR in the clinic and at night. The HR response to bicycle exercise was less in the control group than in the LVH group. The maximal AP and the rise in AP during bicycle exercise did not differ between groups. The LVM index did not correlate with the office AP or with maximal AP during effort, but did correlate negatively with the office HR and with the HR prior to the exercise test. The most significant correlations were found, in decreasing order, between LVM and daytime systolic AP, night systolic AP, and daytime diastolic AP. The hypertensive patients without LVH had a significantly higher ratio of office/day ambulatory mean AP than did those with LVH. In these patients without LVH, the “white coat” phenomenon may be an important cause of the elevated office AP, hence the importance of 24-hour ambulatory AP monitoring in identifying those subjects who will develop LVH.

ISSN:0002-9629    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Hypocalcemia is a major stimulus for parathyroid hormone secretion and presumably the major cause of parathyroid hyperplasia in chronic hypocalcemic syndromes. We could find no data to indicate what degree, duration, or frequency of hypocalcemia is needed to produce parathyroid hyperplasia in humans. We have monitored the effects of thrice weekly hypocalcemic parathyroid stimulation for 10 weeks. Measurements were made during a study designed to test the feasibility of carrying out a randomized, blinded trial of “chelation therapy,” a widely used but unproven method to treat atherosclerotic symptoms. Eight patients received infusions of disodium ethylenediamine-tetraacetic acid (EDTA) and six received placebo infusions thrice weekly for ten weeks. The EDTA infusions (50 mg/kg over three hours) lowered serum ionized calcium at two hours by an average of 0.20 mmol/L and trebled the immunoreactive parathyroid hormone (iPTH) value. Basal serum iPTH, ionized calcium and 1,25-dihydroxyvitamin D values, measured just before the infusion, did not change significantly after 10 weeks of treatment with either EDTA or placebo. The increment in serum iPTH produced by the EDTA-induced hypocalcemia was also unchanged. Lowering ionized serum calcium to values below the normal range three times a week for 10 weeks is not a sufficient stimulus to cause a detectable increase in basal or stimulated parathyroid function.

ISSN:0002-9629    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

A method was developed for the assay of the CF-lectin factor in amniotic fluid using samples from fetuses identified by other means as having or not having cystic fibrosis (CF). The method involves protein removal from the amniotic fluid by filtration through Centricon-10 Amicon filters, admixture of filtrate with normal serum as a source of IgM, and incubation in 5% Dextran-Sulfate with mouse red blood cells to detect specific hemagglutination. Blind samples submitted from four different laboratories were used to evaluate the ability of the assay to differentiate CF fetuses from fetuses without CF. Storage of samples from one laboratory had been quite prolonged and was associated with poor correlations. Freezing and thawing of samples were shown to deactivate the CF-lectin factor. In three of the four studies, CF lectin was detected in 77% of pregnancies identified as CF at birth, prenatally through microvillar enzyme assay or through DNA analysis of terminated pregnancies. Eighty-three percent of samples identified as normal were confirmed as such by a lack of CF-lectin activity. These data suggest that CF fetuses produce, and are exposed to, the CF-lectin factor at least as early as the second trimester of gestation.

ISSN:0002-9629    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The final step in neutrophil bacterial killing is formation of a toxic halide complex. For this reason, we studied neutrophil function in children receiving bromide anticon-vulsant therapy. Whole blood and serum were obtained from 7 patients with seizure disorders treated orally with triple bromide elixir to examine neutrophil function as measured by luminol enhanced chemiluminescence (CL). Serum bromide concentrations [Br−] were determined concomitantly. There was a direct correlation between [Br−] and CL activity of neutrophils (r = 0.87) with peak CL responses significantly higher than controls when [Br−] were in the therapeutic range (10–20 mM). With [Br−] above 25 mM, CL activity was reduced. Serum from patients also enhanced CL of control neutrophils with a similar relationship to measured [Br−].To confirm that enhanced neutrophil activity was attributable to [Br−] use, [Br−] ranging from 0—50 mM were added to control neutrophils in otherwise normal physiologic conditions and the CL assay was performed. Results expressed as percent of control values were as follows: [Br−] 5 mM, 110%; 10 mM, 158%; 15 mM, 194%; 20 mM, 252%; 25 mM, 136%; 30 mM, 364%; and 50 mM, 205%.These data demonstrate that Br−enhances phagocytic and bactericidal activity of neutrophils and suggest that Br−therapy may augment host defense capabilities.

ISSN:0002-9629    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The hypothesis that β2-sympathomimetics augment digitalis-induced arrhythmias and antagonize its positive inotropic action was tested in isolated, electrically driven guinea-pig left atria. Alone, O.3 mM terbutaline enhanced myocardial force generation but did not induce dysrhythmia. Terbutaline shortened the time to the onset of 3 µM ouabain-induced arrhythmia by approximately 75% from 19.7 ± 3.2 minutes to 5.7 ± 1.2 minutes (p < 0.005). The enhancement of arrhythmias appeared to be the result of triggering ouabain-induced delayed afterdepo-larizations (DAD) into overt arrhythmia. The effect of terbutaline was antagonized by blocking cardiac β-adrenoceptors with propranolol. Terbutaline did not affect the ability of ouabain to increase myocardial contractility.

ISSN:0002-9629    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

A 41-year-old woman with acute myelomonocytic leukemia in remission died of a rapidly progressive necrotizing pneumonia while in the recovery phase following consolidation chemotherapy. Autopsy revealed disseminated toxoplasmosis. Although this syndrome has been well described to present as a neurologic complication in certain immunocompromised patients, it is rare in acute leukemia, and non-neurologic presentations are even more unusual. This case emphasizes the need to be suspicious of toxoplasmosis in immunocompromised patients even in the absence of neurologic signs or symptoms.

ISSN:0002-9629    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

We report a case of an HIV-infected adult with Chlamydia pneumoniae. Our patient presented with a clinical picture suggestive of Pneumocystis carinii pneumonia (PCP), but did not respond to empiric anti-PCP therapy. The diagnosis was eventually confirmed by bron-choscopy and serology. C. pneumoniae pneumonia should be considered in the differential of pathogens that cause interstitial infiltrates in HIV-infected persons.

ISSN:0002-9629    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The expression of the metallopro-teinase stromelysin correlates with the progression of chemically induced squamous cell carcinomas. We demonstrate that the expression of activated stromelysin in papilloma-derived cells enhances in vitro cell invasion. We also demonstrate that the Ha-ras oncogene induces the transcription of the stromelysin gene through an AP-1 dependent pathway. The hypothesis is that alterations in oncogenes and suppressor genes influence stromelysin expression and thus influence subsequent steps of tumor invasion and metastasis.

ISSN:0002-9629    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The proenzyme fragment of the 72 kDa type IV collagenase contains a conserved amino acid sequence, MRKPRCGN(V)PDV, that is shared with other members of the matrix metalloproteinase family, such as interstitial collagenase and stromelysin. This sequence is lost upon the autocatalytic removal of the 80—84 amino acids from the amino terminus of these proenzymes following enzyme activation. The loss of this profragment converts the latent proenzyme species into a stable active enzyme species. In the present study, we demonstrate that this conserved prosegment sequence is an inhibitor of these enzymes and plays a critical role in maintenance of the latent state of the matrix metalloproteinases.Peptides containing the conserved sequence, MRKPRCGNPDV, were capable of inhibiting activated enzyme. Free cysteine was also an effective inhibitor, whereas reduced glutathione was a less effective inhibitor. Oxidized glutathione was not inhibitory. The 72 kDa type IV collagenase holoproenzyme preparations did not contain a free cysteinyl side chain that reacted with the sulfhydryl substitution reagent 5, 5'-dithiobis(2-nitrobenzoic acid) (Ellman's reagent). However, addition of ethylenediaminetetraacetic acid to the reaction mixture to generate the apoenzyme form resulted in the detection of titrable sulfhydryl side chains. Based on these data, we postulate that in the latent enzyme state the conserved profragment sequence interacts with the metal atom at the active site through a sulfhydryl-metal atom coordination that is further stabilized by the amino acyl residues surrounding the essential73Cys residue. Disturbance of this interaction results in enzyme activation. This provides an explanation for the activation mechanism of enzymes of the collagenase family.

ISSN:0002-9629    

出版商:OVID    

年代:1991

数据来源: OVID

ISSN:0002-9629    

出版商:OVID    

年代:1991

数据来源: OVID