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Biomedical subjects

Y M Chen

Publications and source records attributed to Y M Chen.

At least 163 records · Page 9Linked to original sources
PubMed1993

Differences in dynamic autoregulation of renal blood flow between SHR and WKY rats.

In halothane-anesthetized Wistar-Kyoto (WKY) rats the single-nephron blood flow and the proximal tubule pressure oscillate at a frequency of 35-50 mHz because of the operation of the tubuloglomerular feedback (TGF) mechanism. In spontaneously hypertensive rats (SHR) the oscillations are replaced by chaotic fluctuations. We sought to determine whether this change was associated with a change in the dynamic autoregulation of renal blood flow. In halothane-anesthetized 250- to 320-g SHR and WKY rats, renal blood flow was measured during "white noise" forcing of arterial blood pressure. The frequency response of renal vascular admittance was estimated by the method of autoregressive-moving averages. In the frequency band below 60-70 mHz there was a significant difference in the transfer functions between the two strains of rats. This was due mainly to an increased phase difference, but also to a decreased magnitude of the admittance in SHR at frequencies below 20-30 mHz. Above 70 mHz there was no significant difference in the transfer functions. Because TGF is active in the low frequency band (below approximately 100 mHz), whereas the myogenic mechanism also acts in the higher frequency band, we conclude that the change in the dynamics of TGF leads to a change in the dynamic autoregulation of renal blood flow between SHR and WKY rats. This change results in a more efficient dynamic autoregulation of renal blood flow in the SHR compared with the WKY rats. The functional consequences of this, in terms of the regulation of salt and water excretion, are not presently known.

Animals↗
PubMed1993

Silicone fluid-induced pulmonary embolism.

Silicone fluid injection for mammary augmentation is a well-known illegal procedure. It has been associated with many complications, including local tissue granulomatous reaction, chronic infection, and sclerosis, but pulmonary involvement in human beings has been documented in only six cases. We describe three more such cases of pulmonary embolism. These three patients were all female, young, and previously healthy. They received the procedures only for cosmetic reasons. Unfortunately, one of them died and another lived with the sequelae of pulmonary fibrosis. The mortality rate of the nine total patients with pulmonary embolism induced by silicone fluid, including our three cases, is 33%. Because of this high mortality rate and long-term sequelae of pulmonary fibrosis, no silicone fluid injection should be given for cosmetic reasons, especially in mammary augmentation in which a large volume of silicone fluid is more likely to be used, and the early use of corticosteroid therapy may be helpful.

Adult↗
PubMed1993

Atrial natriuretic peptide and blood pressure responses during acute sodium loading in patients with essential hypertension.

Atrial natriuretic peptide (ANP) response during acute saline loading and its relationship to changes in blood pressure (BP) and sodium excretion were studied in 21 patients with essential hypertension (EH) and nine normotensive volunteers. Following 2 liters of isotonic saline infusion at a rate of 500 mL/hour, plasma ANP concentrations in patients with EH increased significantly from 69.9 +/- 6.0 (mean +/- SEM) to 103.6 +/- 17.1 pg/mL (p < 0.05) in the first hour and peaked at the second hour. In normal subjects, the increase in plasma ANP was not significant until the third hour of infusion (64.6 +/- 6.2 to 82.0 +/- 7.5 pg/mL, p < 0.05). Mean BP (MBP) remained stable and the natriuretic responses were similar in the two groups. However, hypertensive patients with a prompt rise in ANP during the initial two hours of infusion (fast responders) maintained a BP balance more efficiently than those with a delayed rise in ANP (slow responders), as the latter displayed a significant increase in MBP two hours after saline loading (126 +/- 5 to 133 +/- 5 mmHg, p < 0.05). Fast responders also had a greater percent of suppression of plasma aldosterone (-49.7 +/- 9.2 vs 15.9 +/- 42.0%, p = 0.05) one hour after saline loading, and a higher increment of natriuresis (263.9 +/- 43.8 vs 97.5 +/- 27.4%, p < 0.025) in the second hour of infusion than slow responders. Our results indicate that during acute saline loading, patients with EH have a faster and greater rise in plasma ANP than normotensives.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Heterogeneous blood pressure response to furosemide and captopril in primary aldosteronism.

The hypertension associated with primary aldosteronism (PA) is often regarded as volume dependent/salt-sensitive. However, not all patients sustain an increase in blood pressure upon sodium loading. In order to examine the sodium sensitivity in PA, 21 patients with aldosteronoma were tested for acute hypotensive response to intravenous furosemide and oral captopril. Ten patients having a decrease in mean blood pressure (MBP) exceeding 5% at the second hour after a 20 mg furosemide injection were defined as diuretic-responders (DR), while the remainder were defined as diuretic-non-responders (DN). The DR group had a higher baseline MBP (135 +/- 6 [mean +/- SE] vs 121 +/- 4 mmHg, p < 0.05) and serum sodium concentration (145.7 +/- 1.4 vs 143.0 +/- 0.7 mmol/L, p < 0.05) than the DN group. The extent of natriuresis induced by furosemide was not different between the two subgroups. Following 100 mg of captopril administered orally, the DR group had a smaller change in MBP (%) than the DN group (3.08 +/- 5.14 vs -7.78 +/- 3.37, p < 0.05). According to the different BP responses to furosemide and captopril, we conclude that PA patients may be further divided into DR and DN. The DR group had a good response to diuretics whereas the DN group responded better to converting enzyme inhibitors. This classification of PA in terms of blood pressure response to furosemide may have therapeutic implications.

Adult↗
PubMed1993

Correlation between renin responsiveness to furosemide and antihypertensive effect of captopril in patients with normal-renin essential hypertension.

The relationship between renin responsiveness to furosemide and the antihypertensive effect of captopril in patients with normal-renin essential hypertension were studied in 23 patients including nine men (mean age, 41 years) and 14 women (mean age, 40 years). Those who had an increment of more than 50% in plasma renin activity (PRA) two hours after an intravenous injection of 20 mg furosemide were classified as group A (n = 13) and the others were classified as group B (n = 10). Baseline PRA, plasma aldosterone and mean blood pressure (MBP) were not different between the two groups. Both groups showed no significant difference in natriuresis following furosemide administration. Significant change in MBP was observed after an oral dose of 100 mg captopril within four hours in group A, but not in group B. These data suggest that renin responsiveness to a single intravenous dose of furosemide can be a useful test for predicting the therapeutic response to captopril in patients with normal-renin essential hypertension. The furosemide test had a sensitivity of 75%, a specificity of 64%, a positive predictive value of 69% and a negative predictive value of 70%.

Adult↗
PubMed1993

Blood pressure response to angiotensin converting enzyme inhibitor in essential hypertension: its relation to the renin status and natriuresis during acute sodium loading.

We examined the antihypertensive response to enalapril and its relation to the changes of the renin-angiotensin-aldosterone axis (RAA) in essential hypertensive patients. The responders, whose blood pressure reduced after enalapril administration, had significant elevation of plasma renin activity after enalapril (7.5 +/- 4.0 to 31.9 +/- 10 ng/mL/h, p < 0.05). There was no significant change in the plasma renin activity of the nonresponders (3.0 +/- 1.0 to 5.6 +/- 1.9 ng/mL/h). Natriuretic response to acute salt loading was compared between the two subgroups. The natriuresis on acute salt loading of nonresponders was better than that of the responders (82.9 +/- 13.2 vs 44.5 +/- 5.7 mmol/4h, p < 0.05). These results imply that the RAA and extracellular fluid volume both contribute in different ways to the maintenance of high blood pressure in different subgroups of essential hypertension.

Adult↗
PubMed1993

Renin suppressibility and blood pressure response during acute sodium loading in patients with essential hypertension.

Sequential changes in renin-aldosterone secretions and blood pressure (BP) response during acute sodium (Na) loading were studied in 50 patients with essential hypertension (EH) and nine normotensive volunteers. Following an infusion of 2 L of isotonic saline at a rate of 500 mL/h, plasma renin activity (PRA) and the plasma aldosterone concentration (PAC) were similarly suppressed, while sodium excretion appreciably increased in hypertensive as well as normotensive subjects. When patients were divided into two subgroups according to the extent of renin suppression, 26 were classified as adequate responders with the proportion of decrement of PRA at the end of the infusion exceeding 50% of the baseline values, while 24 were inadequate responders with a decrement of less than 50%. The extent of renin suppression was consistently greater in adequate responders than in inadequate responders throughout the course of infusion. Adequate responders also had a higher pre-saline PRA and attained a smaller post-saline natriuretic response than inadequate responders. Although the mean BP in both subgroups remained stable at all periods, inadequate responders had a minor but significantly higher percent of increment of MBP at the end of the infusion than adequate responders (3.6 +/- 2.0 vs -1.7 +/- 1.4%, p < 0.05). These results suggest that renin suppressibility during acute Na loading may be either linked with maintenance of BP homeostasis or may merely reflect the sodium-volume status of essential hypertension, with patients with greater suppression of renin being more Na-volume resistant than those with less inhibition.

Adult↗
PubMed1993

Cardiovascular autonomic dysfunction in non-insulin-dependent diabetes mellitus and its relation to renal dysfunction.

To investigate the relationship between cardiovascular autonomic neuropathy and nephropathy in patients with non-insulin-dependent diabetes mellitus (NIDDM), 45 patients underwent noninvasive cardiovascular reflex tests, including the Valsalva ratio, the 30:15 ratio and postural changes in systolic blood pressure (delta SBP), along with measurement of creatinine clearance (CCr) and daily protein excretion (DPE). Clinical symptoms in 30 patients were also noted and correlated with the results of the autonomic function tests. Thirty-four normal subjects underwent the same cardiovascular reflex tests and served as controls. The results showed that NIDDM patients had a significantly lower 30:15 ratio than normal subjects. However, no significant difference in either the Valsalva ratio or delta SBP was found between diabetic patients and controls. A positive correlation between the 30:15 ratio and CCr, but not DPE, was noted in diabetics. Although abnormal cardiovascular reflex tests appeared in patients who had no autonomic symptoms, abnormal test results were not parallel with the severity of symptoms. These results show that NIDDM patients have poorer cardiovascular autonomic function which may precede the appearance of autonomic symptoms. The 30:15 ratio was weakly correlated with CCr and this suggests that the incidence of cardiovascular dysfunction increases as the renal functional reserve decreases.

Adult↗
PubMed1993

Changes in renin activity, aldosterone level and electrolytes in pregnancy-induced hypertension.

In order to observe the sequential changes in the renin-angiotensin-aldosterone system (RAAS) in hypertensive pregnancies, blood and urine samples of pregnant women were collected every four weeks from the 20th week of gestation to the fourth week after delivery in a consecutive and prospective study. Nine subjects developed pregnancy-induced hypertension in later gestation, and six of them with proteinuria were classified as having preeclampsia. The gestational ages at the onset of hypertension were the 28th week for one patient, the 32nd week for three patients and the 36th week for five patients. Plasma renin activity in most of the cases decreased to non-pregnant levels after hypertension was established, while the plasma aldosterone level did not. Marked variations in daily sodium and potassium excretion were observed at the various gestational weeks, while serum concentrations of these electrolytes changed only within a narrow range. No correlation between the changes in RAAS and electrolytes were shown in our cases.

Adult↗
PubMed1993

Chromosome studies in HTLV-I, -II, and HIV-1, -2 cell lines infected in vivo and in vitro.

HTLV-I, II and HIV-1, 2 are T-cell tropic viruses, all belonging to the retrovirus family. These viruses are transmitted horizontally by intimate contact or through blood products. The study of chromosomal changes in these T cells may enhance our understanding of the nature and mechanism of these viral infections. However, because of the cytopathic effect of these viruses on T cells, the direct observation of abnormalities in these cells is sometimes difficult. We performed chromosomal analysis on six HTLV-I cell lines from patients with HTLV-I-positive leukemia/lymphoma, one HTLV-I variant cell line, and two HTLV-II-positive cell lines. The results of these studies were compared with the findings in an earlier (published) study of direct preparations and short-term cultures of cells from 11 HTLV-I-positive NIH patients. Our study also included cytogenetic analysis of seven established cell lines and six normal peripheral bloods infected in vitro with the HTLV-IIIB strain of HIV-1 (five cell lines and six bloods) or HIV-2 (two lines); all were studied both before and after viral infection. The results showed that all six HTLV-I cell lines and the variant cell line had multiple chromosomal changes: three lines had deletions of chromosome 6, with breakpoints between q21 and q25. Nine of the 11 NIH patients with HTLV-I had clonal abnormalities, and six of these nine had chromosome 6 deletions with breakpoints ranging from band q11 to band q23. The high incidence of 6q involvement may be of considerable significance in this clinical subgroup of HTLV-I patients. The two HTLV-II cell lines were established from patients suffering from HTLV-II infection. Both of these cell lines had translocations of chromosome 21 at p11, and both had extra copies of chromosome 20; no known oncogenes or receptors are located on these two chromosomes. Chromosome 17 was the chromosome most frequently involved (three lines) in the five HIV-1-infected cell lines, followed by chromosomes 3 and 21; it is of interest that NGL (also known as C-ERBB2 or NEU oncogene), CD7 (a lymphocyte antigen), HTLV-1 receptor, NGFR (nerve growth factor receptor), and MIC6 are all cell surface antigens coded by genes on chromosome 17q. No specific chromosome abnormalities were found in the normal blood samples infected with HIV-1, and no unique chromosome changes were noted in the two cell lines infected with HIV-2; however, the infected H9 line had a chromosome 17 abnormality, a translocation involving band 17p11.

Cell Line↗
PubMed1993

[Staffing levels and patient needs in the intensive care unit].

The current study sought to utilize a patient classification system to investigate staffing and patient needs along with nursing care distribution in our intensive care units. The study employed a factor type analysis to design a patient need checklist (for our six ICUs) in order to determine staff load and nursing requirements. Snapshot observations were also taken to survey the distribution of nursing care time. The results of the two methods provide an estimate of current staffing needs, they also show that there is no significant difference between our surgical and internal medicine wards. On average, direct care accounts for 40.1% of the time schedule; indirect care, 37.3%; related care, 6.0%; and individual time, 16.6%. The average patient grade lies between I and III; and workload index, between 4.4 and 11.5. The average nursing time per patient per shift is 2.88 hours, and the average workload per person is estimated at 5.7-5.8 hours. By comparing the number of personnel currently employed and the estimated number needed, we discovered that two units are understaffed, and three are overstaffed. The understaffed units are all surgical units; the overstaffed ones, internal medicine units. To conclude the study, we examined the nature and complexity of nursing duties in the hopes of returning non-nursing responsibilities to the proper medical organizations. Our ultimate goal is to realize the full potential and improve the quality of our nursing personnel.

Female↗
PubMed1993

[Effects of anoxia and reoxygenization on the vascular contraction induced by two subtypes of alpha 1-adrenergic receptor].

The changes of the contraction induced by activation of alpha 1-adrenergic receptors during anoxia and reoxygenization were observed in isolated rat renal arteries (containing mainly alpha 1A), aortae (containing mainly alpha 1B) and pulmonary arteries (containing both alpha 1A and alpha 1B). In the renal arteries, pD2 values were increased and the maximal contractile responses were decreased during anoxia, which could be recovered 60 min after reoxygenation. In the aorta, pD2 values were decreased and the maximal responses were unchanged during anoxia, but did not return to normal 60 min after reoxygenization. The pulmonary arteries showed both the changes of renal arteries and of aorta. The results suggest that the changes during anoxia and reoxygenization are different in the different subtypes of alpha-adrenergic receptor.

Animals↗
PubMed1992

Atrial natriuretic peptide degradation by CPA47 cells: evidence for a divalent cation-independent cell-surface proteolytic activity.

Atrial natriuretic peptide (ANP) is rapidly cleared and degraded in vivo. Nonguanylate-cyclase receptors (C-ANPR) and a metalloproteinase, neutral endopeptidase (EC 3.4.24.11) (NEP 24.11), are thought to be responsible for its metabolism. We investigated the mechanisms of ANP degradation by an endothelial-derived cell line, CPA47. CPA47 cells degraded 88% of 125I-ANP after 1 h at 37 degrees C as determined by HPLC. Medium preconditioned by these cells degraded 41% of the 125I-ANP, and this activity was inhibited by a divalent cation chelator, EDTA. Furthermore, a cell-surface proteolytic activity degraded 125I-ANP in the presence of EDTA when receptor-mediated endocytosis was inhibited either by low temperature (4 degrees C) or by hyperosmolarity at 37 degrees C. The metalloproteinase, NEP 24.11, is unlikely to be the cell-surface peptidase because 125I-ANP is degraded by CPA47 cells at 4 degrees C in the presence of 5 mM EDTA. These data indicate that CPA47 cells can degrade ANP by a novel divalent cation-independent cell-surface proteolytic activity.

Atrial Natriuretic Factor↗
PubMed1992

Lymph node tuberculosis: 7-year experience in Veterans General Hospital, Taipei, Taiwan.

We retrospectively studied 71 cases of lymph node tuberculosis confirmed by culture or pathology from 1983 to 1989. Young adults were most frequently involved and the female to male ratio was 3:2. of 71 patients, three-quarters presented with palpable masses and two-thirds were asymptomatic. The cervical nodes were most frequently involved. Roentgenographic evidence of pulmonary tuberculosis was detected in 42% of patients and sputum culture-positive tuberculosis occurred in 7%. Tuberculin skin testing is less useful in our country due to routine BCG vaccination during infancy and early childhood. Selective excisional biopsy in addition to clinical information was necessary for differential diagnosis. 48 patients received regular treatment and were followed up for at least 1 year. Fresh nodes or enlargement of existing nodes developed in 10% of patients during treatment. Residual nodes were present in 10% of patients at the end of 9-month treatment with rifampicin, isoniazid and ethambutol, including prolonged or modified regimens in some individuals. In conclusion, in areas with a high frequency of tuberculous strains presenting a primary resistance to isoniazid, a 9-month regimen of rifampicin, isoniazid and ethambutol is recommended for lymph node tuberculosis.

Adult↗
PubMed1992

HTLV among Israeli intravenous drug abusers.

Since human T lymphotropic virus (HTLV) infection was recently described in Israel and other Middle Eastern countries, we have investigated the presence of HTLV type 1 and type 2 in a group of 299 intravenous (IV) drug abusers who were seen at a large methadone clinic in the Tel Aviv area in 1986-1987. We found that 1.3% were seropositive to HTLV. Further testing revealed that HTLV1 was the only HTLV serotype. In addition, no coinfection HIV1/HTLV1 and no HIV2 infection were detected. Since all HTLV seropositives were born in Middle Eastern countries, did not travel outside Israel and were not infected by HIV1 or by HTLV type 2, it is possible that the source of HTLV1 infection in that group was in an endemic reservoir of HTLV1 in Israel. The detection of HTLV1 among IV drug abusers and among other groups in Israel necessitates more extensive HTLV testing in at-risk populations.

Adult↗