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Biomedical subjects

C W Lam

Publications and source records attributed to C W Lam.

At least 127 records · Page 7Linked to original sources
PubMed1997

Dialysate cell population and cancer antigen 125 in stable continuous ambulatory peritoneal dialysis patients: their relationship with transport parameters.

We investigated the total cell count and cell population of the overnight peritoneal dialysis effluent (PDE) by flow cytometry in 76 stable continuous ambulatory peritoneal dialysis (CAPD) patients. The mean percentage of mesothelial cells and macrophages was 4.4% and 57%, respectively. A higher percentage of dead cells among the mesothelial cells compared with other cell populations in the PDE was observed. Peritoneal transport properties were studied in every patient by determining the dialysate to plasma ratio of creatinine concentration (D/P) at the fourth hour of the peritoneal equilibration test, and the mass transfer area coefficient of creatinine (MTACCr) or glucose. Cancer antigen 125 (CA125), suggested as a bulk marker for the mesothelial mass in stable peritoneal dialysis patients, was determined in the PDE. No correlation was demonstrated between CA125 and the number of mesothelial cells, lymphocytes, or macrophages in the PDE. A significant correlation was observed between CA125 and different parameters of peritoneal transport (D/P and MTACCr). On the contrary, neither the history of peritonitis nor the duration of CAPD appeared to affect the CA125 concentration in the PDE. The lack of correlation between CA125 in the PDE and the duration of CAPD may be related to the early loss of peritoneal transport properties as a result of the use of hypertonic dialysate in the majority of our patients with small-volume CAPD (3 x 2 L daily exchange). Our findings suggest that CA125 may not necessarily correlate well with the number of mesothelial cells in PDE. In patients with vanishing of the mesothelial layer, the measurement of CA125 (as a bulk marker for the mesothelial mass in the peritoneum) may reflect the change of peritoneal transport properties.

Adult↗
PubMed1997

Chinese adults are less susceptible than whites to age-related endothelial dysfunction.

OBJECTIVES: We sought to assess the effects of aging on the endothelial physiology of a group of Chinese adults. BACKGROUND: Several studies have documented an association between aging and progressive arterial endothelial dysfunction in white subjects. We hypothesized that age-related endothelial dysfunction, an important event in atherosclerosis, might be less marked in southern Chinese subjects, in whom the prevalence of coronary heart disease is only approximately 20% of that in industrialized countries. METHODS: We studied endothelial function in 76 healthy adults aged 16 to 70 years: 38 Chinese from a village of 3,000 people in southern China and 38 white subjects from Sydney, Australia. In each ethnic group, there were 19 younger persons (16 to 40 years) and 19 older adults (55 to 70 years). None had evidence of diabetes, hypertension or clinical vascular disease or had ever been regular cigarette smokers. With the use of high resolution external vascular ultrasound, brachial artery diameter was measured at rest, after flow increase (causing endothelium-dependent dilation) and after sublingual nitroglycerin (an endothelium-independent dilator). RESULTS: Endothelium-dependent dilation was similar in young Chinese (mean +/- SD 8.3 +/- 2.5%), young whites (7.9 +/- 2.0%) and older Chinese (6.8 +/- 2.9%), but it was significantly impaired in older whites (1.8 +/- 2.5%, p < 0.001 by analysis of variance). On multivariate analysis, older age was associated with impaired endothelium-dependent dilation (p < 0.001) (independent of the effects of serum cholesterol, gender and vessel size) in the white but not in the Chinese subjects (p = 0.83). Nitroglycerin-induced dilation was not significantly different with aging in either ethnic group. CONCLUSIONS: Endothelium-dependent dilation is similar in the arteries of healthy young Chinese and white adults. With older age, however, Chinese subjects are less susceptible to impaired endothelial function.

Adolescent↗
PubMed1997

Interference of creatinine measurement in CAPD fluid is dependent on glucose and creatinine concentrations.

BACKGROUND: High glucose concentration in CAPD fluid is known to interfere with creatinine measurement, which is required for assessment of peritoneal membrane permeability and adequacy of dialysis. Correction formulae have been proposed but they may be method/analyser-dependent. We studied such interference in detail. METHODS: CAPD fluid was diluted to prepare six specimens with glucose concentrations ranging from 9.1 to 154.4 mmol/l. To each specimen, creatinine standard was added to give five different concentrations from 50 to 800 mumol/l. The 30 specimens were assayed for creatinine with six routine clinical chemistry analysers (Hitachi 911 and 747, Technicon RAXT and SMAC3, Beckman CX7, and Kodak Ektachem 700). Creatinine interference was calculated by subtracting the apparent creatinine concentration with corresponding baseline creatinine concentration (measured at glucose = 9.1 mmol/l) in the same series. RESULTS: At constant creatinine concentration, interference increased with increasing glucose concentration to varying extents (up to 200%) amongst the six analysers. At constant glucose concentration, interference decreased with increasing creatinine concentration in analysers using the alkaline picrate reaction but increased in the Kodak analyser using enzymatic assay. CONCLUSION: Interference of creatinine measurement in CAPD fluid is dependent on glucose and creatinine concentrations, and each centre should derive specific correction formulae for its analytical system.

Ascitic Fluid↗
PubMed1997

A characteristic dissection microscopy appearance of a renal biopsy of a Fabry heterozygote.

We report a 15-year-old Fabry heterozygote presenting to us with asymptomatic proteinuria. During the dissection-microscopic examination, the glomeruli exhibited a characteristic swollen, glistening and white appearance. They were swollen and bulged out from the surface of the renal core. The glomerular tufts appeared to be filled with opaque and whitish material giving them a pale white discoloration. This appearance is due to the accumulation of glycosphingolipids in visceral epithelial cells of the kidney. This feature is important for the investigation of female patients with asymptomatic proteinuria, as in two thirds of Fabry heterozygotes the characteristic skin lesions are absent, and thus heterozygous Fabry disease may not be considered. We suggest that this easily demonstrable appearance can be the first evidence for the disease and pathologists should be aware of it in future.

Adolescent↗
PubMed1997

Pituitary-adrenal response in preterm very low birth weight infants after treatment with antenatal corticosteroids.

Antenatal corticosteroids have been widely used for the prevention of respiratory distress syndrome in preterm neonates, yet little is known about their effects on the hypothalamic-pituitary-adrenal axis in these infants. We prospectively evaluated pituitary-adrenal function in 61 preterm (< 32 gestational weeks), very low birth weight (< 1500 g) infants on days 7 and 14 of life using the human CRH stimulation test. The baseline and poststimulation plasma ACTH and serum cortisol concentrations did not differ significantly between infants whose mothers received no antenatal corticosteroids, and those whose mothers received 1-2 doses or > 2 doses (mean 7.2 doses) of prenatal dexamethasone (P = > 0.12). The number of doses of dexamethasone and the time intervals between the last dose of drug and delivery did not significantly affect the pituitary-adrenal responsiveness on days 7 and 14 of life. Among infants who did not require mechanical ventilation at the time of the human CRH test, significantly higher plasma ACTH (P < 0.014) and lower serum cortisol concentrations (P < 0.02) were found on day 14 than on day 7. In contrast, none of the poststimulation hormone concentrations were significantly different in ventilated infants between days 7 and 14. The relationship between the blood hormone concentrations in each time epoch (day 7 and day 14) and possible confounding factors including gestational and postconceptional age, birth weight, sex, Apgar scores, mode of delivery, single or higher order births, and mode of ventilation were determined. Plasma ACTH concentrations on day 7 were found to be significantly higher in ventilated than in nonventilated infants (P = 0.006). However, none of the aforementioned factors correlated significantly with plasma ACTH concentrations on day 14. Serum cortisol concentrations on day 7 were significantly higher in infants of greater gestational age (P = 0.039) and birth weight (P = 0.013), with lower Apgar scores at 1 and 5 min (P = 0.021 and P = 0.049, respectively), and in those delivered vaginally (P = 0.047). Similarly, serum cortisol concentrations on day 14 were found to be significantly higher in infants with lower Apgar scores at 1 and 5 min (P = 0.011 and P = 0.014, respectively) and in infants requiring mechanical ventilation (P = 0.014). Our results suggest that single or multiple courses of antenatal dexamethasone have no long-lasting suppressive effects on pituitary-adrenal function in preterm, very low birth weight infants. Maturation of pituitary function appears to be more advanced than adrenal function. The organ's ability to respond appropriately to various stressful stimuli indicates that the pituitary-adrenal axis is highly responsive at these early gestational ages.

Adrenal Cortex Hormones↗
PubMed1997

The pituitary-adrenal responses to exogenous human corticotropin-releasing hormone in preterm, very low birth weight infants.

To evaluate the pituitary-adrenal reserve and to standardize the methodology of performing the human CRH (hCRH) stimulation test, we performed the hCRH test on 14 preterm (< 32 gestational weeks), very low birth weight infants, who did not receive antenatal or postnatal corticosteroid treatment, on days 7 and 14 of life. Blood samples were obtained 0 (baseline), 15, 30, and 60 min after an iv dose of hCRH (1 microgram/kg). The plasma ACTH concentration rose from a basal value of 5.7 +/- 0.6 pmol/L (mean +/- SEM) to 11.9 +/- 2.1 pmol/L (P < 0.005), 9.2 +/- 1.2 pmol/L (P < 0.005), and 7.7 +/- 0.8 pmol/L (P < 0.005) at 15, 30, and 60 min, respectively. The corresponding rises in serum cortisol from a basal concentration of 396 +/- 67 nmol/L were 509 +/- 71 nmol/L (P < 0.0001), 647 +/- 62 nmol/L (P < 0.0001), and 578 +/- 60 nmol/L (P < 0.0001). The plasma ACTH concentration consistently peaked early at 15 min, whereas the maximum cortisol response occurred 30 min post-hCRH stimulation. No significant differences were detected between the hCRH tests performed on days 7 and 14 (P > 0.15). Mechanical ventilation, infant gender, and mode of delivery did not significantly influence the hormonal responses (P > 0.25). We have defined in this study the pattern, the magnitude of the pituitary-adrenal response, and the timing of the peak concentrations of plasma ACTH and serum cortisol in relation to a standard iv dose of hCRH. The hCRH test in very low birth weight infants appears to be safe and reproducible, and produces a pituitary-adrenal response comparable to that seen in older children and adults, indicating that pituitary-adrenal function is mature at these early stages of gestation.

Adrenocorticotropic Hormone↗
PubMed1997

Pituitary-adrenal suppression and recovery in preterm very low birth weight infants after dexamethasone treatment for bronchopulmonary dysplasia.

High dose dexamethasone is frequently used for the treatment of neonatal respiratory conditions and to facilitate weaning from mechanical ventilation in preterm, very low birth weight infants. However, very little is known about the severity, site, and duration of steroid-induced hypothalamic-pituitary-adrenal axis suppression in this category of patients. Twenty-three preterm, very low birth weight infants who received a full 3-week dose-tapering course of dexamethasone were prospectively studied, with a human CRH stimulation test performed at three different times: before the start of steroid treatment (week 0), immediately after the course (week 3), and 4 weeks after stopping dexamethasone (week 7). Plasma ACTH and serum cortisol concentrations were measured at 0 (baseline), 15, 30, and 60 min. Immediately after the steroid course (week 3), both basal and poststimulation plasma ACTH and serum cortisol concentrations were markedly suppressed. The hormone concentrations at 0, 15, 30, and 60 min in week 3 were significantly lower than their corresponding levels in week 0 (P < 0.0001 for both ACTH and cortisol) and week 7 (P < 0.0001 and P < 0.005 for ACTH and cortisol, respectively). In contrast, when the hormone levels in week 7 were compared to their corresponding concentrations in week 0, only the 60 min serum cortisol concentration in week 7 was significantly lower (P = 0.02). The currently used dosage of dexamethasone caused severe pituitary-adrenal suppression immediately after treatment, but substantial recovery of the endocrine axis was observed 4 weeks after discontinuation of therapy. Although the recovery appeared to be earlier with the pituitary center, both pituitary and adrenal glands were capable of mounting a biochemically adequate response to exogenous human CRH stimulation at this stage. Steroid replacement therapy may be desirable at a time of stress in the immediate posttreatment period, but it would seem unnecessary 1 month after stopping dexamethasone treatment.

Adrenal Gland Diseases↗
PubMed1997

Dialysis adequacy of Asian patients receiving small volume continuous ambulatory peritoneal dialysis.

The usage of three x 2 liter daily exchanges is adopted as the standard CAPD regime in Hong Kong over the last 10 years due to budgetary constraint. This dialysis prescription is considered suboptimal in Western standard. However, the necessity of maintaining Kt/V > 1.7 for CAPD dialysis adequacy is not unanimously agreed. We performed a cross-sectional study of 117 patients on CAPD. Seventy-eight percent of our patients had 3 x 2 liter daily exchange while the rest had 4 daily exchanges. Fifteen percent of patients were diabetic. Patients with Kt/V < 1.7 were similar to those with Kt/V > 1.7 in age, duration of CAPD, BUN, plasma creatinine, albumin, peritonitis rate, and incidence of hypertension. Patients with Kt/V > or = 1.7 had higher hemoglobin, higher nPCR, more residual renal function; and more of them received 4 daily exchanges. Their peritoneal permeability did not differ. Their employment and rehabilitation status was also similar. Our 5-year survival was 79% despite a lower Kt/V. Notably, the protein catabolic rate of our patients was higher than that in Western patients. This is likely due to dietary difference. Our study suggests small-volume dialysis may be acceptable in Asian population with smaller body size given the financial constraint.

Adult↗
PubMed1997

Bioavailability of Chinese rifapentine during a clinical trial in Hong Kong.

SETTING: A clinical trial of rifapentine in Hong Kong. OBJECTIVE: Assessment of the bioavailability of the Chinese rifapentine used in the trial. DESIGN: The content of rifapentine in serum samples taken from 287 patients during the administration of four batches of the drug was measured by microbiological assay. RESULTS: An initial comparison of areas under curve obtained in a random allocation to 40 patients of rifapentine either of Western or Chinese origin indicated that the bioavailability of the Chinese drug was 74% of the Western drug. The bioavailability of the second batch was found to be about 66% of the Western drug. The dose of the last two batches of rifapentine was therefore increased from the planned 600 mg to 750 mg, or briefly to 900 mg; serum concentrations were then similar to those obtained with the Western drug. Bioavailability did not change during the use of each drug batch. CONCLUSION: A comparison of the results obtained in the trial with the initial two batches and the final batches will estimate the effects of rifapentine dose size on its efficacy and toxicity.

Adult↗
PubMed1995

Effect of fluvastatin on lipoprotein profiles in treating renal transplant recipients with dyslipoproteinemia.

A single, blinded placebo-drug trial was conducted to study the efficacy and safety of fluvastatin, a new 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, in treating dyslipoproteinemia in 16 renal transplant recipients who had been on an immunosuppressive regimen that included cyclosporine (CsA). They were studied for 32 consecutive weeks, with 4 weeks of baseline treatment, 4 weeks of placebo, 12 weeks of treatment with fluvastatin 20 mg daily, and 12 weeks of fluvastatin 40 mg daily. Blood samples were obtained every 4 weeks for measurement of the lipoprotein profiles, which included total cholesterol (TC), triglyceride, low density lipoprotein (LDL)-, high density lipoprotein (HDL)-, HDL2-, HDL3- and very low density lipoprotein-cholesterol (C), apolipoprotein (Apo) A-1, Apo B, and lipoprotein(a). Fifteen patients completed the trial. After 12 weeks of treatment, fluvastatin 20 mg significantly reduced TC by 13.4% (from 6.7 +/- 0.5 [mean +/- SEM] to 5.8 +/- 0.2 mmol/L), LDL-C by 22% (from 4.1 +/- 0.3 to 3.2 +/- 0.2 mmol/L), and Apo B by 13.2% (from 159.6 +/- 8.8 to 138.6 +/- 9.2 mg/dl) (P < 0.005). The subsequent 12-week treatment of fluvastatin 40 mg significantly reduced TC by 16.4% to 5.6 +/- 0.3 mmol/L, LDL-C by 29.3% to 2.9 +/- 0.2 mmol/L, and Apo B by 18.2% to 130.6 +/- 5.5 mg/dl (P < 0.00005). There was no significant change in levels of other lipoproteins, including lipoprotein (a). There were no significant changes in the whole blood trough CsA concentrations, renal and liver function tests, and serum creatine phosphokinase level during treatment when compared with baseline and placebo. No patient complained of myalgia or failed to complete the study due to side effects of the drug. Fluvastatin appears to be safe and effective in treating dyslipoproteinemia in renal transplant recipients who are maintained on CsA.

Adult↗
PubMed1995

The prevalence and clinical significance of pulmonary infection due to non-tuberculous mycobacteria in Hong Kong.

An unexpected increase in positive sputum cultures of non-tuberculous mycobacteria (NTM) was noted in Hong Kong in 1990 compared to previous years, in contrast to a steady decline in the number of positive cultures of Mycobacterium tuberculosis. A retrospective case note study was therefore undertaken to ascertain the clinical importance of the rise in NTM isolates. A representative sample of 183 of the 675 patients with NTM isolates from sputum during 1990 was identified. Cases were assigned to groups according to whether there was evidence of progressive pulmonary disease due to NTM (group 1), persisting colonization without evidence of progressive disease (group 2) or transient isolation of NTM without evidence of progressive disease (group 3). Of 168 cases with adequate clinical and radiological records, 28 (16.7%) represented progressive disease due to NTM and 6 (3.6%) represented persisting colonization. The remainder were both transient and clinically insignificant. Most patients (71%) with progressive pulmonary disease due to NTM had pre-existing lung damage, and 50% had received anti-tuberculous therapy for documented M. tuberculosis previously. The commonest organism involved was the M avium complex. Eighty-six percent of patients with progressive disease and 83% of those with persisting colonization had at least one smear positive sputum specimen, whereas only 2% of patients with sputum contamination had a smear positive sputum sample (P < 0.0001). M. malmoense, M. xenopi and M. fortuitum all appear to be rare causes of significant NTM disease in Hong Kong. However, M. chelonei caused four cases of progressive disease within the study population, two of which were fatal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Diagnosis of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes in a Chinese family by PCR/restriction enzyme analysis.

The clinical presentation and the biochemical and molecular genetic findings are described in a 13 year old Chinese boy with MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes). The diagnosis was initially suspected because of the characteristic clinical features and the strong family history of convulsions. Using polymerase chain reaction-restriction enzyme analysis, the heteroplasmic nt3243 A-->G mutation in mtDNA of peripheral blood leucocytes and a muscle sample was demonstrated. The oligosymptomatic relatives were then screened by this method and the degree of heteroplasmy was analysed. This appears to be the first report of a MELAS family in Hong Kong with this described mutation. Molecular genetic techniques are advantageous in the diagnosis of MELAS.

Journal Article↗
PubMed1995

The interaction of fluvastatin and cyclosporin A in renal transplant patients.

A possible interaction between fluvastatin, a new HMG CoA reductase inhibitor, and cyclosporin A (CsA) was studied in 16 stable renal transplant patients with dyslipoproteinemia despite dietary control. They entered a 12-week study period: 4-week baseline, 4-week placebo and 4-week fluvastatin treatment (20 mg daily). Weekly trough whole blood CsA concentrations were measured by monoclonal antibody immunoassay. Serial renal and liver function tests and creatine phosphokinase (CPK) were monitored. The mean trough levels of CsA during fluvastatin treatment were 115.6 micrograms/l compared with 114.3 micrograms/l and 113.3 micrograms/l in the baseline and placebo period, respectively. Apart from a small decrease in serum albumin level (from a mean of 38.6 g/l to 37.9 g/l), there were no significant changes in renal and liver functions or CPK levels. No adverse effects were reported. Fluvastatin (20 mg daily) may be used safely without extra monitoring of blood CsA concentrations in renal transplant patients.

Adult↗
PubMed1994

IgD multiple myeloma with thoracic spine compression due to epidural extra-osseous tumour spread.

On initial presentation of a patient with IgD multiple myeloma there were no features to suggest an unusual variant. Two months later she developed spinal cord compression due to an IgD plasmacytoma. This complication of IgD myeloma has rarely been reported. During the course of the disease and using the routine laboratory protocol for investigating and identifying paraproteins, including IgD, the patient's results became indistinguishable from those in Bence-Jones proteinuria myeloma.

Acute Disease↗
PubMed1994

Charge distribution of IgA-lambda in IgA nephropathy.

The finding that eluted mesangial IgA and serum IgA from patients with IgA nephropathy had a restricted anionic charge contrasting with normal serum IgA prompted us to study the charge of the kappa and lambda subclasses of IgA. Serum IgA from 11 patients with IgA nephropathy and 11 controls was purified by affinity chromatography by binding to jacalin. The charges of IgA were studied by a novel method. The spectrotype of total IgA was first studied by isoelectric focusing and immunoblotting. IgA lambda and IgA kappa was further analyzed by reacting with specific monoclonal antibodies. The amount of IgA with different pIs was analyzed by computerized densitometry. The anionic:cationic (A:C) ratio of IgA using pI 5.6 as the dividing point was greater in patients (at clinical quiescence and during exacerbation) than in controls (1.67 +/- 0.31 versus 1.36 +/- 0.27, p < 0.025). IgA lambda in both groups was anionic (A:C ratio 2.22 +/- 0.77 versus 2.36 +/- 0.36) and IgA kappa was cationic (A:C ratio 1.15 +/- 0.36 versus 1.04 +/- 0.39) but no difference in the A:C ratio was demonstrated. The increased A:C ratio in total IgA in patients was due to raised serum IgA lambda (kappa/lambda ratio 1.11 +/- 0.14 in patients and 1.51 +/- 0.16 in controls, p < 0.01). We had previously shown a predominant mesangial deposition of IgA lambda in IgA nephropathy. Animal experiments have revealed the preferential mesangial deposition of immune complexes is related to their anionic charges. Our data of raised anionic IgA lambda in IgA nephropathy may be important in determining its selective mesangial binding that could contribute to the immunopathogenesis.

Adolescent↗
PubMed1994

Acute, 2-week, and 13-week inhalation toxicity studies on dimethylethoxysilane vapor in Fischer 344 rats.

Dimethylethoxysilane (DMES), a volatile liquid, is used by NASA to waterproof the heat-protective silica tiles and blankets on the Space Shuttle. Acute, 2-wk, and 13-wk inhalation exposures to DMES vapor were conducted in male and female Fischer 344 rats. In the acute study, rats were exposed to 4000, 2000, 1000, 500, or 0 (control) ppm DMES for 4 h and observed for 14 days. There were no deaths. Narcosis and ataxia were observed in rats of the two highest concentrations only. These signs disappeared within 1 h following exposure. There were no DMES-related gross or microscopic tissue lesions in rats of all exposure groups. In the 2-wk study, rats were exposed for 6 h/day, 5 days/wk to 3000, 1000, 300, 100, or 0 ppm DMES. During exposure, narcosis was observed in rats of the 3000 and 1000 ppm groups. There was a mild decrease in body weight gain in rats of the 3000 ppm group. A decrease in platelet count, an increase in bile acids, and reduced weights of the thymus, testis, and liver were observed in rats of the 3000 ppm group. Microscopically, hypospermatogenesis and spermatid giant cells were observed in the seminiferous tubules of the testes of rats exposed to 3000 ppm DMES. In the 13-wk study, rats were exposed 6 h/day, 5 days/wk to 2000, 600, 160, 40, or 0 ppm DMES. During exposure, rats of the 2000 ppm group exhibited mild narcosis and loss of startle reflex. Recovery from these central nervous system signs was rapid. Body weights were mildly decreased for rats of the 2000 ppm group. There were no exposure-related effects in hematology, serum chemistry, or urinalysis. Female rats of the 2000 ppm group had delayed estrous cycles (6 days compared to 5 days in control rats). Noteworthy organ weight changes in rats of the 2000 ppm group included decreases in thymus, liver, and testicular weights; however, pathologic lesions were observed in the testes only. Sperm motility, epididymal sperm count, and testicular spermatid count were dramatically reduced. Microscopic lesions included degeneration of the seminiferous tubular cells, pyknosis or absence of germ cells, and hypospermia in the epididymis. Rats of the 600 ppm group had a slight decrease in thymic weight and a transient decrease in body weight. Results of the acute, 2-wk, and 13-wk inhalation studies indicate DMES concentrations of 1000 ppm and higher produce narcosis that rapidly disappears following exposure. Repeated exposure of rats to DMES at either 3000 ppm for 2 wk or 2000 ppm for 13 wk caused testicular atrophy and hypospermia in male rats. Female rats exposed to 2000 ppm for 13 wk had delayed estrous cycles. Toxicological effects in rats of the 600 ppm group were minimal and equivocal. The 160 ppm concentration was a no-observable-effect level (NOEL) for 13 wk of exposure to DMES.

Administration, Inhalation↗