Sub-acute herpes simplex virus myelitis in a patient with esophageal cancer on chemo-radiation with 5-fluorouracil: a case report

No reported cases to date describe herpes simplex virus (HSV) myelitis in association with cancer and chemo-radiation. We report a case of sub-acute HSV myelitis in a 54-year-old man receiving chemo-radiation with 5-flourouracil for esophageal cancer who presented to the emergency department with increasing numbness in both lower limbs that gradually spread to waist level. Magnetic resonance imaging with gadobutrol contrast 1 week later showed transverse myelitis involving the dorsal columns. Radiation-induced myelitis was suspected, and the patient was initially treated with dexamethasone; however, CSF analysis revealed HSV myelitis. Treatment with antivirals resolved much of the numbness. HSV myelitis can be confused with complications of radiation or malignancy in patients presenting with focal neurological deficits.

Factors affecting the decline in incidence of diabetes in the Diabetes Prevention Program Outcomes Study (DPPOS)

During the first 7 years of the Diabetes Prevention Program Outcomes Study (DPPOS), diabetes incidence rates, when compared with the Diabetes Prevention Program (DPP), decreased in the placebo (-42%) and metformin (-25%), groups compared with the rates in the intensive lifestyle intervention (+31%) group. Participants in the placebo and metformin groups were offered group intensive lifestyle intervention prior to entering the DPPOS. The following two hypotheses were explored to explain the rate differences: "effective intervention" (changes in weight and other factors due to intensive lifestyle intervention) and "exhaustion of susceptible" (changes in mean genetic and diabetes risk scores). No combination of behavioral risk factors (weight, physical activity, diet, smoking, and antidepressant or statin use) explained the lower DPPOS rates of diabetes progression in the placebo and metformin groups, whereas weight gain was the factor associated with higher rates of progression in the intensive lifestyle intervention group. Different patterns in the average genetic risk score over time were consistent with exhaustion of susceptibles. Results were consistent with exhaustion of susceptibles for the change in incidence rates, but not the availability of intensive lifestyle intervention to all persons before the beginning of the DPPOS. Thus, effective intervention did not explain the lower diabetes rates in the DPPOS among subjects in the placebo and metformin groups compared with those in the DPP.

Sex hormone binding globulin and sex steroids among premenopausal women in the diabetes prevention program

CONTEXT

It is unknown whether intensive lifestyle modification (ILS) or metformin changes sex steroids among premenopausal women without a history of polycystic ovarian syndrome (PCOS).

OBJECTIVES

We examined 1-year intervention impact on sex steroids (estradiol, testosterone, dehydroepiandrosterone, and androstenedione [A4]) and SHBG and differences by race/ethnicity.

PARTICIPANTS

A subgroup of Diabetes Prevention Program participants who were premenopausal, not using estrogen, without a history of PCOS or irregular menses, and who reported non-Hispanic white (NHW), Hispanic, or African-American race/ethnicity (n = 301).

INTERVENTIONS

Randomization arms were 1) ILS with the goals of weight reduction of 7% of initial weight and 150 minutes per week of moderate intensity exercise, 2) metformin 850 mg twice a day, or 3) placebo.

RESULTS

Neither intervention changed sex steroids compared to placebo. ILS, but not metformin, increased median SHBG by 3.1 nmol/L (~11%) compared to decreases of 1.1 nmol/L in the placebo arm (P < .05). This comparison remained significant after adjustment for changes in covariates including waist circumference. However, associations with glucose were not significant. Median baseline A4 was lower in Hispanics compared to NHWs (5.7 nmol/L vs 6.5 nmol/L, P < .05) and increases in A4 were greater in Hispanics compared to NHWs (3.0 nmol/ vs 1.2 nmol/L, P < .05), and these differences did not differ significantly by intervention arm. No other racial/ethnic differences were significant.

CONCLUSIONS

Among premenopausal glucose-intolerant women, no intervention changed sex steroids. ILS increased SHBG, although associations with glucose were not significant. SHBG and sex steroids were similar by race/ethnicity, with the possible exception of lower baseline A4 levels in Hispanics compared to NHWs.

Distribution, fate and risk assessment of antibiotics in sewage treatment plants in Hong Kong, South China

Occurrence, removal, consumption and environmental risks of sixteen antibiotics were investigated in several sewage treatment plants (STPs) featuring different treatment levels in Hong Kong, China. Cefalexin, ofloxacin and erythromycin-H(2)O were predominant with concentrations of 1020-5640, 142-7900 and 243-4740 ng/L in influent, respectively; their mass loads were comparable to levels reported in urban regions in China and were at the high end of the range reported for western countries. The target antibiotics behaved differently depending on the treatment level employed at the STPs and relatively higher removal efficiencies (>70%) were observed for cefalexin, cefotaxime, amoxicillin, sulfamethoxazole and chloramphenicol during secondary treatment. ß-lactams were especially susceptible to removal via the activated sludge process while macrolides were recalcitrant (<20%) in the dissolved phase. Two fluoroquinolones, ofloxacin (4%) and norfloxacin (52%), differed greatly in their removal efficiencies, probably because of disparities in their pK(a) values which resulted in different sorption behaviour in sludge. Overall antibiotic consumption in Hong Kong was back-calculated based on influent mass flows and compared with available prescription and usage data. This model was verified by a good approximation of 82% and 141% to the predicted consumption of total ofloxacin, but a less accurate estimate was obtained for erythromycin usage. Risk assessment indicated that algae are susceptible to the environmental concentrations of amoxicillin as well as the mixture of the nine detected antibiotics in receiving surface waters.

Are elevated circulating intercellular adhesion molecule 1 levels more strongly predictive of diabetes than vascular risk? Outcome of a prospective study in the elderly

AIMS/HYPOTHESIS

The aim of this prospective study was to determine whether circulating intercellular adhesion molecule (ICAM) 1, as a potential surrogate of 'endothelial activation', is more strongly associated with risk of vascular events than with incident diabetes.

METHODS

We related baseline ICAM-1 levels to vascular events (866 CHD and stroke events in 5,685 participants) and incident diabetes (292 in 4,945 without baseline diabetes) in the elderly over 3.2 years of follow-up.

RESULTS

ICAM-1 levels correlated positively with triacylglycerol but negatively with LDL- and HDL-cholesterol. ICAM-1 levels were higher in those who developed diabetes (388.6 +/- 1.42 vs 369.4 +/- 1.39 ng/ml [mean+/-SD], p = 0.011) and remained independently associated with new-onset diabetes (HR 1.84, 95% CI 1.26-2.69, p = 0.0015 per unit increase in log[ICAM-1] after adjusting for classical risk factors and C-reactive protein). By contrast, ICAM-1 levels were not significantly (p = 0.40) elevated in those who had an incident vascular event compared with those who remained event-free, and corresponding adjusted risk associations were null (HR 0.98, 95% CI 0.80-1.22, p = 0.89) in analyses adjusted for other risk factors.

CONCLUSIONS/INTERPRETATION

We show that elevated ICAM-1 levels are associated with risk of incident diabetes in the elderly at risk, despite no association with incident cardiovascular disease risk. We suggest that perturbations in circulating ICAM-1 levels are aligned more towards diabetes risk.

Is a priming dose of insulin necessary in a low-dose insulin protocol for the treatment of diabetic ketoacidosis?

OBJECTIVE

The purpose of this study was to assess the efficacy of an insulin priming dose with a continuous insulin infusion versus two continuous infusions without a priming dose.

RESEARCH DESIGN AND METHODS

This prospective randomized protocol used three insulin therapy methods: 1) load group using a priming dose of 0.07 units of regular insulin per kg body weight followed by a dose of 0.07 unit x kg(-1) x h(-1) i.v. in 12 patients with diabetic ketoacidosis (DKA); 2) no load group using an infusion of regular insulin of 0.07 unit . kg body weight(-1) x h(-1) without a loading dose in 12 patients with DKA, and 3) twice no load group using an infusion of regular insulin of 0.14 x kg(-1) x h(-1) without a loading dose in 13 patients with DKA. Outcome was based on the effects of insulin therapy on biochemical and hormonal changes during treatment and recovery of DKA.

RESULTS

The load group reached a peak in free insulin value (460 microU/ml) within 5 min and plateaued at 88 microU/ml in 60 min. The twice no load group reached a peak (200 microU/ml) at 45 min. The no load group reached a peak (60 microU/ml) in 60-120 min. Five patients in the no load group required supplemental insulin doses to decrease initial glucose levels by 10%; patients in the twice no load and load groups did not. Except for these differences, times to reach glucose <or=250 mg/dl, pH >or=7.3, and HCO(3)(-) >or=15 mEq/l did not differ significantly among the three groups.

CONCLUSIONS

A priming dose in low-dose insulin therapy in patients with DKA is unnecessary if an adequate dose of regular insulin of 0.14 unit x kg body weight(-1) x h(-1) (about 10 units/h in a 70-kg patient) is given.

Thirty years of personal experience in hyperglycemic crises: diabetic ketoacidosis and hyperglycemic hyperosmolar state

CONTEXT

Diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar state (HHS) cause major morbidity and significant mortality in patients with diabetes mellitus. For more than 30 yr, our group, in a series of prospective, randomized clinical studies, has investigated the pathogenesis and evolving strategies of the treatment of hyperglycemic crises. This paper summarizes the results of these prospective studies on the management and pathophysiology of DKA.

SETTING

Our earliest studies evaluated the comparative efficacy of low-dose vs. pharmacological amounts of insulin and the use of low-dose therapy by various routes in adults and later in children. Subsequent studies evaluated phosphate and bicarbonate therapy, lipid metabolism, ketosis-prone type 2 patients, and use of rapid-acting insulin analogs as well as leptin status, cardiac risk factors, proinflammatory cytokines, and the mechanism of activation of T lymphocytes in hyperglycemic crises.

MAIN OUTCOME

The information garnered from these studies resulted in the creation of the 2001 American Diabetes Association (ADA) technical review on DKA and HHS as well as the ADA Position and Consensus Paper on the therapy for hyperglycemic crises.

CONCLUSIONS

Areas of future research include prospective randomized studies to do the following: 1) establish the efficacy of bicarbonate therapy in DKA for a pH less than 6.9; 2) establish the need for a bolus insulin dose in the initial therapy of DKA; 3) determine the pathophysiological mechanisms for the absence of ketosis in HHS; 4) investigate the reasons for elevated proinflammatory cytokines and cardiovascular risk factors; and 5) evaluate the efficacy and cost benefit of using sc regular insulin vs. more expensive insulin analogs on the general ward for the treatment of DKA.

Lymphotoxin-alpha C804A polymorphism is a risk factor for stroke. The PROSPER study

Inflammation plays a prominent role in the development of atherosclerosis, which is the most important risk factor for vascular events. Lymphotoxin-alpha (LTA) is a pro-inflammatory cytokine and is found to be expressed in atherosclerotic lesions. We investigated the association between the C804A polymorphism within the LTA gene and coronary and cerebrovascular events in 5804 participants of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER). The primary endpoint was the combined endpoint of death from coronary heart disease, non-fatal myocardial infarction, and clinical stroke. Secondary endpoints were the coronary and cerebrovascular components separately. All associations were assessed with a Cox-proportional hazards model adjusted for sex, age, pravastatin use, and country. Our overall analysis showed a significant association between the C804A polymorphism and the primary endpoint (p = 0.03). After stratification for gender, this association was found only in males. Furthermore, we found that the association between the C804A polymorphism and the primary endpoint was mainly attributable to clinical strokes (p = 0.02). The C804A polymorphism in the LTA gene associates with clinical stroke, especially in men. But further research is warranted to confirm our results.

Polycyclic musks in green-lipped mussels (Perna viridis) from Hong Kong

Six polycyclic musk compounds [Cashmeran (DPMI), Celestolide (ADBI), Phantolide (AHMI), Traseolide (ATII), Tonalide (AHTN), and Galaxolide (HHCB)] were analysed in marine green-lipped mussels (Perna viridis) from Hong Kong. ADBI, HHCB and AHTN were detected in almost all samples, while AHMI, ATII and DPMI were not detected. Concentrations of ADBI, HHCB and AHTN in mussels ranged from below detection limit-0.0743 (mean: 0.0246), 0.247-6.08 (mean: 1.15) and 0.0591-0.738 (mean: 0.190)mg/kg lipid weight, respectively. Mussels from two sampling sites in central Victoria Harbour contained the highest total polycyclic musk levels, suggesting that these waters are heavily influenced by domestic sewage. Concentrations of HHCB and AHTN detected in the mussel samples were the second highest and the highest levels, respectively, compared to global concentrations. A preliminary risk assessment indicated that HHCB and AHTN in mussels pose little or no threat to the health of shellfish consumers. Nevertheless, more comprehensive studies are required to further assess the ecological and human health risks associated with polycyclic musks.

Synthetic polycyclic musks in Hong Kong sewage sludge

Synthetic polycyclic musks [Cashmeran (DPMI), Celestolide (ADBI), Phantolide (AHMI), Traseolide (ATII), Tonalide (AHTN), and Galaxolide (HHCB)] were determined in dewatered sludge samples from 10 major sewage treatment plants in Hong Kong using primary treatment (PT), secondary treatment (SecT) or chemical-enhanced primary treatment (CEPT) methods. The concentrations of HHCB, AHTN, AHMI and ADBI ranged from below detection limits to 78.6mg/kg dry weight. HHCB and AHTN were the two predominant polycyclic musks in sludge samples, suggesting the extensive use of these two polycyclic musks in Hong Kong. Polycyclic musk levels in CEPT sludge were significantly higher than those in SecT and PT sludge, suggesting that CEPT sludge has a higher ability to retain polycyclic musks. Comparisons to global concentrations revealed that HHCB and AHTN concentrations detected in Hong Kong sludge ranked first and second respectively. However, the estimated levels of HHCB and AHTN in the discharged effluent from sewage treatment plants may pose low potential risks to aquatic organisms according to the threshold effect levels derived for fish. Nevertheless, the polycyclic musks released in sewage treatment plant effluents may bioconcentrate and bioaccumulate in the marine environment in Hong Kong. Therefore, monitoring studies in marine ecosystems, particularly on the two prevailing polycyclic musks, are necessary.

Genetic variation in the interleukin-1 beta-converting enzyme associates with cognitive function. The PROSPER study

Inflammation is thought to play an important role in the development of cognitive decline and dementia in old age. The interleukin-1 signalling pathway may play a prominent role in this process. The gene encoding for interleukin-1 beta-converting enzyme (ICE) is likely to influence IL-1 beta levels. Inhibition of ICE decreases the age-related increase in IL-1 beta levels and may therefore improve memory function. We assessed whether genetic variation in the ICE gene associates with cognitive function in an elderly population. All 5804 participants of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) were genotyped for the 10643GC, 9323GA, 8996AG and 5352GA polymorphisms in the ICE gene. Cross-sectional associations between the polymorphisms and cognitive function were assessed with linear regression. Longitudinal associations between polymorphisms, haplotypes and cognitive function were assessed with linear mixed models. All associations were adjusted for sex, age, education, country, treatment with pravastatin and version of test where appropriate. Subjects carrying the variants 10643C and 5352A allele had significantly lower IL-1 beta production levels (P < 0.01). Furthermore, we demonstrated that homozygous carriers of the 10643C and the 5352A allele performed better on all executive function tests at baseline and during follow-up compared to homozygous carriers of the wild-type allele (all P < 0.02). The haplotype with two variants present (10643C and 5352A) was associated with better executive function (all P < 0.02) compared to the reference haplotype without variants. For memory function the same trend was observed, although not significant. Genetic variation in the ICE gene is associated with better performance on cognitive function and lower IL-1 beta production levels. This suggests that low levels of IL-1 beta are protective for memory and learning deficits. Inhibition of ICE may therefore be an important therapeutic target for maintaining cognitive function in old age.

Genetic Variation in the Interleukin-10 Gene Promoter and Risk of Coronary and Cerebrovascular Events: The PROSPER Study

Proinflammatory cytokines, like interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), are implicated in the development of atherosclerosis. The role of anti-inflammatory cytokines, like IL-10, is largely unknown. We investigated the association of four single nucleotide polymorphisms (SNPs) in the promoter region of the IL-10 gene (4259AG, -1082GA, -592CA, and -2849GA), with coronary and cerebrovascular disease in participants of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) trial. All associations were assessed with Cox proportional hazards models adjusted for sex, age, pravastatin use, and country. Haplotype analysis of the four SNPs showed a significant association between haplotype 4 (containing the -592A variant allele) and risk of coronary events (P = 0.019). Moreover, analysis of separate SNPs found a significant association between -2849AA carriers with incident stroke (HR (95%CI) 1.50 (1.04-2.17), P value = 0.02). Our study suggests that not only proinflammatory processes contribute to atherosclerosis, but that also anti-inflammatory cytokines may play an important role.

Sediment TCDD-EQs and EROD and MROD activities in Ranid frogs from agricultural and nonagricultural sites in Michigan (USA)

In vitro studies have demonstrated atrazine-mediated induction of 7-ethoxyresorufin O-deethylase (EROD) activity. EROD is an enzyme active in the metabolism of many compounds, including many xenobiotics. These studies have suggested that atrazine may affect reproductive function by altering steroid metabolism. The goal of this study was to determine whether relationships could be detected between measured atrazine concentrations in surface waters and the liver-somatic index (LSI) and EROD and 7-methoxyresorufin O-deethylase (MROD) activities in the livers of ranid frogs. In addition, sediment dioxin toxic equivalents (TCDD-EQs) were determined using the H4IIE-luc cell bioassay. Adult and juvenile green frogs (Rana clamitans), bullfrogs (R. catesbeiana), and Northern leopard frogs (R. pipiens) were collected from areas with extensive corn cultivation and areas where there was little agricultural activity in south central Michigan in the summer of 2003. Atrazine concentrations at nonagricultural sites ranged from less than the limit of quantification (0.17 microg atrazine/L) to 0.23 microg atrazine/L and did not exceed 1.2 microg atrazine/L at agricultural sites. Sediment TCDD-EQs were measurable only at one agricultural site. Of the measured parameters, only LSI values in adult male frogs differed significantly between agricultural and nonagricultural sites, with greater values observed at agricultural sites. In green frogs, EROD and MROD activities were measurable in both adult and juvenile frogs and were similar among sites. Median EROD activities ranged from 13 to 21 pmol/min/mg protein in adult male green frogs and from 5 to 13 pmol/min/mg protein in adult female green frogs. Juvenile frogs had greater EROD and MROD activities than adult frogs. Bullfrogs and leopard frogs had greater activities than did green frogs. Atrazine concentrations were significantly and negatively correlated with MROD activity in adult male green frogs (Spearman R = -0.800). LSI and EROD and MROD activities of adult female or juvenile green frogs were not significantly correlated with atrazine concentrations. These results suggest that atrazine does not appear to have a consistent association with EROD or MROD activities in wild-caught green frogs.

Plasma steroid hormone concentrations, aromatase activities and GSI in ranid frogs collected from agricultural and non-agricultural sites in Michigan (USA)

The triazine herbicide atrazine has been hypothesized to disrupt sexual development in frogs by up-regulating aromatase activity, resulting in greater estradiol (E2) concentrations and causing feminization in males. The goal of this study was to collect native ranid frogs from atrazine-exposed ponds and determine whether relationships exist between measured atrazine concentrations and the gonadosomatic index (GSI), plasma concentrations of testosterone (T), E2 or 11-ketotestosterone (KT), or with aromatase activity. In the summer of 2002 and 2003, adult and juvenile green frogs (Rana clamitans), bullfrogs (R. catesbeiana) and Northern leopard frogs (R. pipiens) were collected from areas with extensive corn cultivation and areas where there was little agricultural activity in south-central Michigan. Atrazine concentrations were below the limit of quantification at non-agricultural sites. Atrazine concentrations did not exceed 2 microg/L at most agricultural sites, but a concentration of 250 microg atrazine/L was measured in one sample from one site in 2002. Plasma steroid concentrations varied among locations. Aromatase activity was measurable in less than 11% of testes in adult males, and in less than 4% of testes in juvenile males. Median aromatase activities in ovaries of adult females ranged from 3 to 245 pmol/h/mg protein, and maximum activities were 2.5-fold greater in juveniles than in adults. Atrazine concentrations were not significantly correlated with any of the parameters measured in this study. These results indicate that atrazine does not up-regulate aromatase in green frogs in the wild, and does not appear to affect plasma steroid hormone concentrations.

Atrazine concentrations, gonadal gross morphology and histology in ranid frogs collected in Michigan agricultural areas

The triazine herbicide atrazine has been suggested to be a potential disruptor of normal sexual development in male frogs. The goals of this study were to collect native ranid frogs from sites in agricultural and non-agricultural areas and determine whether hypothesised atrazine effects on the gonads could be observed at the gross morphological and histological levels. Juvenile and adult green frogs (Rana clamitans), bullfrogs (R. catesbeiana) and leopard frogs (R. pipiens) were collected in the summers of 2002 and 2003. Atrazine concentrations were below the limit of quantification at non-agricultural sites, and concentrations did not exceed 2 microg/L at most agricultural sites. One concentration greater than 200 microg atrazine/L was measured once at one site in 2002. Hermaphroditic individuals with both male and female gonad tissue in either one or both gonads, were found at a low incidence at both non-agricultural and agricultural sites, and in both adults and juveniles. Testicular oocytes (TO) were found in male frogs at most of the sites, with the greatest incidence occurring in juvenile leopard frogs. TO incidence was not significantly different between agricultural and non-agricultural sites with the exception of juveniles collected in 2003. Atrazine concentrations were not significantly correlated with the incidence of hermaphroditism, but maximum atrazine concentrations were correlated with TO incidence in juvenile frogs in 2003. However, given the lack of a consistent relationship between atrazine concentrations and TO incidence, it is more likely the TOs observed in this study result from natural processes in development rather than atrazine exposure.

Role of insulin secretion and sensitivity in the evolution of type 2 diabetes in the diabetes prevention program: effects of lifestyle intervention and metformin

Insulin resistance and beta-cell dysfunction, two factors central to the pathogenesis of type 2 diabetes, were studied in relation to the development of diabetes in a group of participants with impaired glucose tolerance in the Diabetes Prevention Program (DPP) at baseline and after specific interventions designed to prevent diabetes. Participants were randomly assigned to placebo (n = 1,082), metformin (850 mg twice a day) (n = 1,073), or intensive lifestyle intervention (n = 1,079). The diabetes hazard rate was negatively associated with baseline insulin sensitivity (hazard rate ratio = 0.62-0.94 per SD difference, depending on treatment group and measure of sensitivity) and with baseline insulin secretion (hazard rate ratio = 0.57-0.76 per SD). Improvements in insulin secretion and insulin sensitivity were associated with lower hazard rates in all treatment arms (hazard rate ratio = 0.46-0.95 per SD increase and 0.29-0.79 per SD increase, respectively). In multivariate models that included the three metabolic variables (changes in body weight, insulin sensitivity, and insulin secretion) each significantly and independently predicted progression to diabetes when adjusted for the other two variables. The intensive lifestyle intervention, which elicited the greatest reduction in diabetes incidence, produced the greatest improvement in insulin sensitivity and the best preservation of beta-cell function after 1 year, whereas the placebo group, which had the highest diabetes incidence, had no significant change in insulin sensitivity and beta-cell function after 1 year. In the metformin group, diabetes risk, insulin sensitivity, and beta-cell function at 1 year were intermediate between those in the intensive lifestyle and placebo groups. In conclusion, higher insulin secretion and sensitivity at baseline and improvements in response to treatment were associated with lower diabetes risk in the DPP. The better preventive effectiveness of intensive lifestyle may be due to improved insulin sensitivity concomitant with preservation of beta-cell function.

Williams syndrome in twins

Two sets of identical twins with Williams syndrome have been reported previously. We report on 2 additional sets of presumed identical twins with Williams syndrome. All 4 patients had the typical Williams syndrome facial appearance, growth deficiency, and developmental delay. None of the patients had supravalvular aortic stenoses; however, all were diagnosed as having probable distal pulmonary artery stenosis. In the set of twins in which serum calcium was measured, one twin had an elevated serum ionized calcium level. These 2 sets of twins further document the occurrence of Williams syndrome in identical twins. To our knowledge, there are no reported cases of concordance in dizygotic twins. This adds further support to the likelihood that Williams syndrome is a genetic disorder.

Thyroid dysfunction in patients with type 1 diabetes: a longitudinal study

OBJECTIVE

Cross-sectional studies have reported that the risk of thyroid dysfunction in patients with type 1 diabetes is two- to threefold higher than in the general population. However, longitudinal studies to determine the natural history of thyroid dysfunction in patients with type 1 diabetes are lacking.

RESEARCH DESIGN AND METHODS

We analyzed the incidence of thyroid dysfunction over time in a cohort of 58 patients (26 men and 32 women) enrolled in the Diabetes Control and Complications Trial at the University of Tennessee Health Science Center in 1983 and prospectively followed for 18 years. Patients underwent measurement of thyroid function tests (thyroid-stimulating hormone [TSH], thyroxine, and triiodothyronine) every year and thyroid peroxidase (TPO) antibodies at 4-year intervals.

RESULTS

A total of 18 patients had hypothyroidism, and 1 patient experienced transient hyperthyroidism. Two subjects developed hypothyroidism 7 and 18 years before the development of diabetes and were excluded from the analysis. The mean age of diagnosis was 19 +/- 2 years for type 1 diabetes and 29 +/- 3 years for hypothyroidism. Hypothyroidism was more common in female (41%) than in male (19%) subjects and in patients with positive TPO antibodies. Patients who were TPO positive were 17.91 times as likely to develop hypothyroidism as patients who were TPO negative (95% CI 3.89-82.54). There were no differences in BMI, lipid profile, and HbA(1c) between patients with and without thyroid dysfunction.

CONCLUSIONS

This longitudinal study confirms the association between autoimmune thyroid dysfunction and type 1 diabetes. Our results indicate that all subjects with type 1 diabetes should undergo annual screening by serum TSH measurement to detect asymptomatic thyroid dysfunction, particularly those with positive TPO antibodies.

Testing cognitive function in elderly populations: the PROSPER study. PROspective Study of Pravastatin in the Elderly at Risk

OBJECTIVES

For large scale follow up studies with non-demented patients in which cognition is an endpoint, there is a need for short, inexpensive, sensitive, and reliable neuropsychological tests that are suitable for repeated measurements. The commonly used Mini-Mental-State-Examination fulfils only the first two requirements.

METHODS

In the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER), 5804 elderly subjects aged 70 to 82 years were examined using a learning test (memory), a coding test (general speed), and a short version of the Stroop test (attention). Data presented here were collected at dual baseline, before randomisation for active treatment.

RESULTS

The tests proved to be reliable (with test/retest reliabilities ranging from acceptable (r=0.63) to high (r=0.88) and sensitive to detect small differences in subjects from different age categories. All tests showed significant practice effects: performance increased from the first measurement to the first follow up after two weeks.

CONCLUSION

Normative data are provided that can be used for one time neuropsychological testing as well as for assessing individual and group change. Methods for analysing cognitive change are proposed.

Werner syndrome protein is regulated and phosphorylated by DNA-dependent protein kinase

DNA double-strand breaks (DSBs) are a highly mutagenic and potentially lethal damage that occurs in all organisms. Mammalian cells repair DSBs by homologous recombination and non-homologous end joining, the latter requiring DNA-dependent protein kinase (DNA-PK). Werner syndrome is a disorder characterized by genomic instability, aging pathologies and defective WRN, a RecQ-like helicase with exonuclease activity. We show that WRN interacts directly with the catalytic subunit of DNA-PK (DNA-PK(CS)), which inhibits both the helicase and exonuclease activities of WRN. In addition we show that WRN forms a stable complex on DNA with DNA-PK(CS) and the DNA binding subunit Ku. This assembly reverses WRN enzymatic inhibition. Finally, we show that WRN is phosphorylated in vitro by DNA-PK and requires DNA-PK for phosphorylation in vivo, and that cells deficient in WRN are mildly sensitive to ionizing radiation. These data suggest that DNA-PK and WRN may function together in DNA metabolism and implicate WRN function in non-homologous end joining.

The influence of physical activity on the variability of ambulatory blood pressure

The aim of this study was to assess the contribution of physical activity levels to blood pressure (BP) variability, and to assess the effect age, gender, body mass index, and use of antihypertensive medications on this relationship. We simultaneously monitored 24-h ambulatory BP by automated recorder and activity by actigraphy in 431 patients. Mean activity scores for the 5, 10, 15, and 20 min preceding each BP measurement were calculated, and BP and heart rate were related to these variables using linear mixed model regression. Various patient characteristics were added to the mixed model as covariates. Patients were heterogeneous in age (48 +/- 13 years), sex (49% men), and average 24-h BP (132/81 +/- 15/10 mm Hg). Mean daytime activity level was 44 +/- 15 U. During the daytime, systolic BP (r = 0.33), diastolic BP (r = 0.29), and heart rate (r = 0.42) correlated best with the average activity for the 15 min preceding each measurement (P < .001). Variance was very high, with activity explaining from 0% to 62% of BP variability for different individuals. Men and the obese had a greater reactivity of systolic BP to activity; older patients and those on antihypertensive therapy had a lower reactivity of heart rate. Blood pressure level is significantly associated with physical activity, but the percentage of variance of BP explained by physical activity varies greatly between individuals. Correlation is strongest between BP and average activity integrated over the previous 15 min. Much of the variance in blood pressure remains unexplained.

Nocturnal blood pressure dipping: a consequence of diurnal physical activity blipping?

This study was designed to describe the interaction between physical activity (PA), quantified objectively by electronic activity monitors, and ambulatory blood pressure (ABP), and to test the hypothesis that modifying daily PA can effect significant changes in the diurnal variation in blood pressure and may result in altered dipping/nondipping status of an individual. Initially, 70 individuals underwent simultaneous ABP and electronic activity monitoring (actigraph devices manufactured by Gaewihler Electronics, Switzerland) over a 24-h period. Then, in a prospective study, the dipping/nondipping status of 43 subjects was assessed using ABP recorded over two 24-h periods of differing activity levels. Of the 70 subjects (age 49 +/- 11 years, 42 male) the diurnal variation in systolic blood pressure (20 +/- 12%, step-up from night [120 +/- 12 mm Hg] to day [144 +/- 13 mm Hg]) and diurnal variation in PA score (increment from sleep, 44 +/- 17 units) correlated significantly (R2 = 0.29; P < .05). Of the 43 subjects who underwent ABP monitoring on a more active day, four had a nondipping BP profile; 12 of these same 43 subjects had a nondipping BP profile when monitored on a less active day (chi2 = 4.9; P < .05). These results provide a quantitative description of the contribution of PA, including the sleep/awake status, to blood pressure variation in a group of normotensive and hypertensive individuals. The magnitude of this effect underscores the importance of interpreting 24-h ABP data only in the presence of adequately quantified activity data.

Electronic activity-monitor-derived sleeping and awake times and diurnal variation of blood pressure

BACKGROUND

Results of a number of studies have indicated that target-organ damage is more pronounced in non-dippers, those in whom the blood pressure falls by less than 10% with the onset of sleep, than it is in dippers with comparable clinic blood pressures. However, the standard use of arbitrarily defined daytime and night-time periods, rather than precise estimates of sleeping time and awake time, could limit the accuracy of estimates of diurnal variation of blood pressure and hence of dipping status.

DESIGN AND METHODS

In this study of 102 consecutive patients undergoing ambulatory blood pressure monitoring we compared activity-derived estimates of sleeping and awake blood pressures using electronic activity monitoring and diary records with estimates determined using pre-defined day and night-time periods. The dipping/non-dipping status of each subject was assessed using these three different techniques for defining the awake/asleep time periods.

RESULTS

The sleeping/awake times based on the activity monitor, diary and default data were 2356 h+/-55 min/0754 h+/-50 min, 2326 h+/-61 min/0722 h+/-72 min and 2300 h and 0700 h respectively. The percentage systolic/diastolic falls in blood pressure were 18+/-6/18+/-7% with six non-dippers (activity-monitor-derived data), 16+/-6/17+/-8% and 12 non-dippers (diary data) and 13+/-7/15+/-7% and 21 non-dippers (using the pre-set daytime and night-time periods).

DISCUSSION

Results of this study demonstrate that the extent of the diurnal variation in blood pressure (and hence dipping status) can differ depending on the technique used to define periods of wakefulness and sleep.

Dopamine: a role in the pathogenesis and treatment of hypertension

The catecholamine dopamine (DA), activates two distinct classes of DA-specific receptors in the cardiovascular system and kidney--each capable of influencing systemic blood pressure. D1 receptors on vascular smooth muscle cells mediate vasodilation, while on renal tubular cells they modulate sodium excretion. D2 receptors on pre-synaptic nerve terminals influence noradrenaline release and, consequently, heart rate and vascular resistance. Activation of both, by low dose DA lowers blood pressure. While DA also binds to alpha- and beta-adrenoceptors, selective agonists at both DA receptor classes have been studied in the treatment of hypertension. An unfavourable side-effect profile (largely nausea and orthostasis) have precluded wide use of D2 agonists. In contrast, the D1 selective agonist fenoldopam has been licensed for the parenteral treatment of severe hypertension. Apart from inducing systemic vasodilation it induces a diuresis and natriuresis, enhanced renal blood flow, and a small increment in glomerular filtration rate. Evidence is emerging that abnormalities in DA production, or in signal transduction of the D1 receptor in renal proximal tubules, may result in salt retention and high blood pressure in some humans and in several animal models of hypertension.

Physical activity level is an independent predictor of the diurnal variation in blood pressure

OBJECTIVE

The aim of this study was to define the relationship between physical activity and the magnitude of the percentage fall in blood pressure at night (nocturnal dip).

METHODS

We simultaneously monitored 24-h ambulatory blood pressure and measured physical activity by actigraphy in 434 patients. Blood pressure was measured every 20 min; the actigraph integrated an activity score every 10 s. Mean daytime and night-time activity were calculated from mean scores for the 15 min preceding each blood pressure measurement. Nocturnal dip in systolic and diastolic blood pressure (SBP and DBP) were regressed on mean (log-transformed) daytime activity. Mean night-time activity, age, gender, smoking status, body mass index (BMI) and clinic blood pressure were added into a multiple linear regression.

RESULTS

The patient group was heterogeneous in age, gender and mean 24-h blood pressure. Mean daytime activity level was significantly and positively associated with the magnitude of the nocturnal dip in both SBP and DBP. Increased night-time activity was significantly associated with a smaller nocturnal dip. Older patients had a smaller nocturnal dip per log unit daytime activity. Nocturnal dip in SBP was greater in males, and smaller in those taking antihypertensive medications. Smoking, BMI and clinical blood pressure level were not associated with the extent of the nocturnal dip after adjustment for other factors.

CONCLUSIONS

Daytime and night-time physical activity levels are independently and significantly predictive of the magnitude of the nocturnal dip in blood pressure. Variation in activity may confound interpretation of 24-h ambulatory blood pressure monitoring, and contribute to the poor reproducibility of dipper status.

Ambulatory blood pressure monitoring: which arm?

To determine the effects of routinely selecting the nondominant arm for ambulatory blood pressure monitoring (ABPM) on estimates of patients' blood pressure (BP) and to evaluate the practise of using manual BP from one arm and ambulatory BP from the other on the estimation of white coat effect (WCE), an observational study was conducted in 10 volunteers, exhibiting an interarm resting clinic systolic BP (SBP) difference > or =10 mm Hg. The main outcome measures were: (i) average ambulatory SBP measured on right and left arm simultaneously during 24 h, and (ii) estimate of WCE derived, by current practise, as the difference between the referral clinic BP (the higher of the manual readings from both arms) and ambulatory non-dominant arm BP, contrasted with the WCE calculated as the difference between clinic and ambulatory readings from the same arm (the arm with the higher manual readings). The supine referral clinic SBP was 16+/-6 mm Hg higher in the right compared with the left arm. Average 24 h ambulatory SBP was 6+/-7 mm Hg higher in the right arm (range +17 to -3 mm Hg), P = 0.025. Diastolic BP measurements mirrored the systolic findings. One-third of the WCE, estimated by current practise, could be attributed to inconsistency in the choice of arm for BP measurement. Thus, inconsistency in the selection of arms for BP measurement, by different techniques, may confound estimation of patients' cardiovascular morbidity risk.

Short- and long-term outcome of total parathyroidectomy with immediate autografting versus subtotal parathyroidectomy in patients with end-stage renal disease

A retrospective study was performed in 36 patients with end-stage renal disease (ESRD) comparing total parathyroidectomy followed by immediate autografting into the forearm (total PTX + IA) with parathyroidectomy (subtotal PTX) over a five-year period. Twenty-eight patients underwent subtotal PTX and 8 had total PTX + IA. The two surgical methods were evaluated with respect to preoperative severity of hyperparathyroidism, perioperative morbidity, and the incidence of recurrent hyperparathyroidism. Eleven patients in total (30.6%) developed recurrent hyperparathyroidism; 2/8 (25%) in the total PTX + IA group compared to 9/28 (32.1%) in the subtotal PTX group (p = 0.699). The median time to recurrence was longer in the total PTX + IA group (39 vs. 16 months), and the median long-term postoperative PTH value was lower (81 vs. 199 ng/l), but these differences did not reach statistical significance. In conclusion, the incidence of recurrent hyperparathyroidism is high regardless of surgical modality. However, total PTX + IA may produce more favorable results with respect to median postoperative PTH level and time to recurrence.

The design of a prospective study of Pravastatin in the Elderly at Risk (PROSPER). PROSPER Study Group. PROspective Study of Pravastatin in the Elderly at Risk

The PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) is a randomized, double-blind, placebo-controlled trial designed to test the hypothesis that treatment with pravastatin will diminish risk of subsequent major vascular events in a cohort of men and women (70 to 82 years old) with preexisting vascular disease or significant risk of developing this condition. Five thousand eight hundred four men and women in addition to receiving advice on diet and smoking, have been randomized equally to treatment with 40 mg pravastatin/day or matching placebo in 3 centers (Cork, Ireland, Glasgow, Scotland, and Leiden, The Netherlands). Following an average 3.5-year intervention period, a primary assessment will be made of the influence of this therapy on major vascular events (a combination of coronary heart disease, death, nonfatal myocardial infarction, and fatal and nonfatal stroke). A number of additional analyses will also be conducted on the individual components of the primary end point, on men, on women, and on subjects with and without previous evidence of vascular disease. Finally, an assessment will be made of the effects of treatment on cognitive function, disability, hospitalization or institutionalization, vascular mortality, and all-cause mortality.

Biochemical characterization of a Dictyostelium myosin II heavy-chain phosphatase that promotes filament assembly

In Dictyostelium cells, myosin II is found as cytosolic nonassembled monomers and cytoskeletal bipolar filaments. It is thought that the phosphorylation state of three threonine residues in the tail of myosin II heavy chain regulates the molecular motor's assembly state and localization. Phosphorylation of the myosin heavy chain at threonine residues 1823, 1833 and 2029 is responsible for maintaining myosin in the nonassembled state, and subsequent dephosphorylation of these residues is a prerequisite for assembly into the cytoskeleton. We report here the characterization of myosin heavy-chain phosphatase activities in Dictyostelium utilizing myosin II phosphorylated by myosin heavy-chain kinase A as a substrate. One of the myosin heavy-chain phosphatase activities was identified as protein phosphatase 2A and the purified holoenzyme was composed of a 37-kDa catalytic subunit, a 65-kDa A subunit and a 55-kDa B subunit. The protein phosphatase 2A holoenzyme displays two orders of magnitude higher activity towards myosin phosphorylated on the heavy chains than it does towards myosin phosphorylated on the regulatory light chains, consistent with a role in the control of filament assembly. The purified myosin heavy-chain phosphatase activity promotes bipolar filament assembly in vitro via dephosphorylation of the myosin heavy chain. This system should provide a valuable model for studying the regulation and localization of protein phosphatase 2A in the context of cytoskeletal reorganization.

Molecular characterization and immunolocalization of Dictyostelium discoideum protein phosphatase 2A

Protein phosphatase 2A (PP2A) was previously purified from Dictyostelium and biochemically characterized. The purified PP2A holoenzyme was composed of a 37 kDa catalytic 'C-subunit', a 65 kDa 'A-subunit' and a 55 kDa 'B-subunit'. We report here the characterization of the genes encoding the Dictyostelium PP2A subunits as well as the immunolocalization of the PP2A subunits in Dictyostelium. The cDNAs encoding the B- and C-subunits were isolated from a Dictyostelium library and the deduced amino acid sequences reveal strong conservation with the mammalian PP2A homologues. Southern blot analysis suggests that each of the PP2A subunit genes is present in a single copy. The PP2A subunits were localized mainly to the cytosol in Dictyostelium cells. However, immunofluorescence confocal microscopy demonstrates that the B-subunit of PP2A is highly enriched in centrosomes, suggesting a potential role for this PP2A regulatory subunit in the centrosomal function.

Opioid antagonist modulation of ischaemia-induced ventricular arrhythmias: a peripheral mechanism

Ventricular arrhythmias are an important cause of death after myocardial ischaemia. Animal studies have generated conflicting data on the potentiating or attenuating effects of opioid agonists and antagonists on cardiac rhythm during acute myocardial ischaemia and coronary artery reperfusion. Whether these effects of opioid antagonists are mediated by central or peripheral nervous system mechanisms remains unclear. We examined (a) the effects of peripheral opioid receptor blockade on ischaemia-induced arrhythmia by using methylnaltrexone (MNTX), a novel quaternary derivative of naltrexone (NTX) that does not cross the blood-brain barrier, and (b) whether MNTX would modulate morphine effects during acute coronary artery ligation and reperfusion in the rabbit. The incidence and severity of cardiac arrhythmias were assessed during 40 min of coronary artery occlusion and reperfusion and summarised in an arrhythmia score (AS). MNTX reduced the incidence of ventricular fibrillation (VF) and arrhythmia score during coronary artery occlusion when compared with vehicle (p < 0.05). Naltrexone reduced the incidence of VF (p < 0.05). Although morphine alone had no significant effects, its coadministration blunted the antiarrhythmic properties of MNTX. The data suggest that blockade of opiate receptors outside the central nervous system may protect against ischaemia-induced arrhythmias.

A comparison of the effects of tramadol and morphine on gastric emptying in man

In a previous study using an electrical bioimpedance technique and the paracetamol absorption test, we demonstrated that 0.09 mg.kg-1 of morphine delayed gastric emptying in healthy human volunteers. The aim of this study was to investigate whether analgesic doses of tramadol would cause a delay in gastric emptying similar to conventional opioids. Using the same volunteers and techniques as in our previous study, placebo or tramadol (1 mg.kg-1) was given in a randomised, double-blinded, cross-over placebo-controlled study. Gastric emptying was measured concurrently by a noninvasive epigastric bioimpedance technique and by the paracetamol absorption test. After the ingestion of 500 ml of deionised water plus paracetamol 1.5 g, the mean (SEM) time taken for gastric volume to decrease to 50% (t0.5) was recorded. No difference in gastric emptying rates (t0.5) between placebo, 7.7 (1 min), and tramadol, 9.5 (2 min), was noted. In our previous study, morphine prolonged t0.5 to 21 (3) min (p < 0.03). The maximum concentration and area under the curve of serum paracetamol concentrations following morphine were significantly different from placebo (p < 0.05) and tramadol (p < 0.05). We conclude that tramadol at a dose of 1 mg.kg-1 does not delay gastric emptying in humans.

Opioid-induced delay in gastric emptying: a peripheral mechanism in humans

BACKGROUND

Opioids delay gastric emptying, which in turn may increase the risk of vomiting and pulmonary aspiration. Naloxone reverses this opiate action on gastric emptying, but it is not known whether this effect in humans is mediated by central or peripheral opiate antagonism. The importance of peripheral opioid receptor antagonism in modulating opioid-induced delay in gastric emptying was evaluated using methylnaltrexone, a quaternary derivative of the opiate antagonist naltrexone, which does not cross the blood-brain barrier.

METHODS

In a randomized, double-blind, crossover placebo-controlled study, 11 healthy volunteers were given either placebo (saline), 0.09 mg/kg morphine, or 0.09 mg/kg morphine plus 0.3 mg/kg methylnaltrexone on three separate occasions before ingesting 500 ml deionized water. The rate of gastric emptying was measured by two methods: a noninvasive epigastric bioimpedance technique and the acetaminophen absorption test.

RESULTS

The epigastric bioimpedance technique was sufficiently sensitive to detect opioid-induced changes in the rate of gastric emptying. The mean +/- SD time taken for the gastric volume to decrease to 50% (t0.5) after placebo was 5.5 +/- 2.1 min. Morphine prolonged gastric emptying to (t0.5) of 21 +/- 9.0 min (P < 0.03). Methylnaltrexone given concomitantly with morphine reversed the morphine-induced delay in gastric emptying to a t0.5 of 7.4 +/- 3.0 (P < 0.04). Maximum concentrations and area under the concentration curve from 0 to 90 min of serum acetaminophen concentrations after morphine were significantly different from placebo and morphine administered concomitantly with methylnaltrexone (P < 0.05). No difference in maximum concentration or area under the concentration curve from 0 to 90 min was noted between placebo and methylnaltrexone coadministered with morphine.

CONCLUSIONS

The attenuation of morphine-induced delay in gastric emptying by methylnaltrexone suggests that the opioid effect is mediated outside the central nervous system. Methylnaltrexone may have the potential to decrease the side effects of opioid medications, which are mediated peripherally, while maintaining the central analgesia effect of the opioid.

Supervised drug administration in patients with refractory hypertension unmasking noncompliance

Noncompliance with medication is common, particularly in asymptomatic conditions such as hypertension that require long-term treatment, and is often unsuspected. We describe two patients with refractory hypertension in whom noncompliance was confirmed by a precipitous fall in blood pressure when antihypertensive medications were given under direct supervision.

Mapping of the novel protein kinase catalytic domain of Dictyostelium myosin II heavy chain kinase A

Myosin heavy chain kinase A (MHCK A) in Dictyostelium was identified as a biochemical activity that phosphorylates threonine residues in the myosin II tail domain and regulates myosin filament assembly. The catalytic domain of MHCK A has now been mapped through the functional characterization of a series of MHCK A truncation mutants expressed in Escherichia coli. A recombinant protein comprising the central nonrepetitive domain of MHCK A (residues 552-841) was isolated in a soluble form and shown to phosphorylate Dictyostelium myosin II, myelin basic protein, and a synthetic peptide substrate. The functionally mapped catalytic domain of MHCK A shows no detectable sequence similarity to known classes of eukaryotic protein kinases but shares substantial sequence similarity with a transcribed Caenorhabditis elegans gene and with the mammalian elongation factor-2 kinase (calcium/calmodulin-dependent protein kinase III). We suggest that MHCK A represents the prototype for a novel, widely occurring protein kinase family.

Factors confounding assessment of ambulatory blood pressure monitors, studied during formal evaluation of the Tycos Quiet-Trak

The credibility of studies assessing ambulatory blood pressure monitoring (ABPM) devices will be enhanced by minimizing opportunities to manipulate the outcome through biased selection of patient volunteers, and by insuring that participants are representative of the target patient population. While subjecting the Welch Allyn Quiet-Trak to the British Hypertension Society (BHS) protocol, we examined the extent to which certain candidate characteristics might influence device assessment. The Quiet-Trak achieved an A grade overall. During its field testing, daytime physical activity measured with a wrist-mounted, piezoelectric accelerometer, influenced significantly the rate of measurement rejection. The tertiles of subjects with highest and lowest levels of daytime physical activity (64 +/- 16 and 35 +/- 10 activity units; P < .001) exhibited significantly different measurement rejection rates (10 +/- 3 and 3 +/- 2 daytime rejects; P < .001)). Most rejected readings occurred during episodes of high physical activity. During static evaluation (Phase V), the level of systolic BP influenced the accuracy of diastolic BP estimation; above 190 mm Hg systolic BP, estimates of diastolic BP differed significantly from manual measurements. Subjects' age and arm circumference influenced neither field nor static evaluation. Retrospective comparison of the study subjects with 120 consecutive ABPM clinic attenders revealed (1) that participants in field testing were younger, had lower BP but were equally active compared with clinic patients; and (2) that Phase V participants exhibited higher systolic (155 +/- 42 v 135 +/- 15 mm Hg; P < .001) but similar diastolic BP levels compared to controls. The reliability of ABPM validation protocols would be enhanced by: (a) incorporation of objective measurement of physical activity during field testing, demonstrating normal levels of activity; (b) requiring that field testing be conducted in representative patients rather than normal volunteers; and (c) a greater focus in both static and field testing on those levels of blood pressure that are relevant in clinical practice.

Prostacyclin and thromboxane levels in pleural space fluid during cardiopulmonary bypass

Prostaglandins exhibit a variety of cardiovascular actions that may affect the hemodynamic recovery of the ischemic myocardium after cardiopulmonary bypass. We have observed a decrease in the mean arterial pressure on autotransfusion of the accumulated pleural cavity fluid during operation. One aim of this study was to determine the concentrations of prostacyclin and thromboxane A2 in the pleural cavity fluid by measuring their stable metabolites, 6-keto-PGF1 alpha and thromboxane B2, respectively, in 8 consecutive patients undergoing myocardial revascularization, and to compare them with the arterial levels. A second aim was to quantify the hemodynamic effect of the pleural cavity fluid during operation. The concentration of 6-keto-PGF1 alpha in the pleural cavity fluid was significantly higher than the arterial concentration (mean, 21.6 +/- 18.2 ng/mL; p < 0.01). The concentration of thromboxane B2 was also raised compared with the arterial concentration (mean, 3.62 +/- 5.96 ng/mL; p < 0.2). The percentage fall in the mean arterial pressure was 29.7% +/- 8.86% (p < 0.02), which was transient and lasted 1 to 3.5 minutes. The hemoglobin concentration, potassium level, and pH were also measured. This study shows that the pleural cavity fluid during cardiac operations contains significant amounts of endogenous prostacyclin. Considering the potential benefit of prostacyclin on the recovering myocardium, we believe that this fluid should be transfused as a volume replacement, keeping in mind the transient phase of hemodynamic instability.

Differential effects of chronic oral antihypertensive therapies on systemic arterial circulation and ventricular energetics in African-American patients

BACKGROUND

A comprehensive evaluation of arterial load characteristics and left ventricular energetics in systemic hypertension has been limited by the need for invasive techniques to access instantaneous aortic pressure and flow. As a consequence of this methodological limitation, no data exist on the effects of long-term antihypertensive therapy on global arterial impedance properties and indexes of myocardial oxygen consumption (MVO2). Using recently validated noninvasive techniques, we compared in hypertensive patients the effects of chronic oral treatment with ramipril, nifedipine, and atenolol on arterial impedance and mechanical power dissipation as well as indexes of MVO2.

METHODS AND RESULTS

Sixteen African-American subjects with systemic hypertension were studied with a randomized, double-blind, crossover protocol. Instantaneous central aortic pressure and flow, from which arterial load characteristics can be derived, were estimated from calibrated subclavian pulse tracings (SPTs) and continuous-wave aortic Doppler velocity in conjunction with two-dimensional (2D) echocardiographic measurements of the aortic annulus, respectively. To derive ventricular wall stress and indexes of MVO2, left ventricular short- (M-mode) and long-axis (2D echo) images were acquired simultaneously with SPTs. Data were collected at the end of a 2-week washout period (predrug control) and after 6 weeks of treatment with each agent. Although all three agents reduced diastolic blood pressure to the same extent, different effects on mean and systolic pressures and vascular impedance properties were noted. Nifedipine reduced total peripheral resistance (TPR; 1744 +/- 398 versus 1290 +/- 215 dyne-s/cm5) and increased arterial compliance (ACL; 1.234 +/- 0.253 versus 1.776 +/- 0.415 mL/mm Hg). This improvement in arterial compliance was not entirely accounted for by the reduction in distending pressure. Ramipril also decreased TPR (1740 +/- 292 versus 1437 +/- 290 dyne-s/cm5) and increased ACL (1.214 +/- 0.190 versus 1.569 +/- 0.424 mL/mm Hg), but with this agent, the change in arterial compliance was explained solely on the basis of a reduction in distending pressure. Atenolol, in contrast, did not affect either TPR or ACL. In agreement with the compliance results, nifedipine and ramipril significantly lowered the first two harmonics of the impedance spectrum, but atenolol did not. None of these agents resulted in a significant change in characteristic impedance or in the relative amplitude of the reflected pressure wave. Total vascular mechanical power and percent of oscillatory power remained unaltered with all antihypertensive treatments. Only ramipril and nifedipine reduced the integral of both meridional and circumferential systolic wall stresses, indicating that MVO2 per beat was reduced with these agents. Stress-time index, a measure of MVO2 per unit time, decreased significantly with ramipril but not with nifedipine because of an increase in heart rate noted in 10 of 16 patients (mean increase, 10 beats per minute). Thus, a reduction in MVO2 coupled with unchanged total vascular mechanical power suggests improved efficiency of ventriculoarterial coupling with ramipril and with nifedipine in the subset of patients in whom heart rate remained unchanged. In contrast, there was no evidence of a reduction in wall stress, stress integral, or stress-time index with atenolol.

CONCLUSIONS

The noninvasive methodology used in this study constitutes a new tool for serial and simultaneous evaluation of arterial hemodynamics and left ventricular energetics in systemic hypertension. In this study, we demonstrate the differential effects of chronic antihypertensive therapies on systemic arterial circulation and indexes of MVO2 in African-American subjects. Consideration of drug-induced differential responses of arterial load and indexes of MVO2 with each drug may provide a more physiological approach to the treatment of systemic hypertension in indivi