Stereoisomeric sugar-derived indolizines as versatile building blocks: synthesis of enantiopure di- and tetrahydroxyindolizidines

The synthesis of the sugar-derived (1S,2R,8aR)-1,2-di-O-isopropylidene-1,2,3,5,6,8a-hexahydro-5-oxoindolizine (8) and by analogy of the corresponding stereoisomers ent-8 and ent-7, an epimer at C2 of ent-8, has been accomplished in a straightforward manner. The carbon-carbon double bond and the carbonyl functionalities on the six-membered ring make these nitrogen-containing heterocycles useful building blocks for the efficient preparation of a variety of enantiopure polyhydroxylated indolizidines of interest for their glycosidase inhibitory activity. We report here the synthesis of 2,8a-diepilentiginosine 12 from 8 and the preparation of stereoisomeric 1,2,7,8-tetrahydroxyindolizidines 9-11 performed by OsO4-catalyzed double bond syn dihydroxylation of 7 and 8, followed by deoxygenation of the amide group.

The acute effects of oral ethanol on the hypothalamic-pituitary-adrenal axis in normal human subjects

OBJECTIVE

To evaluate the acute effects of oral ethanol on the hypothalamic-pituitary-adrenal axis in normal human subjects and, in particular, to examine the effect of background alcohol intake and gastrointestinal side-effects on this response.

DESIGN

Plasma ethanol, cortisol, ACTH, corticotrophin-releasing hormone (CRH) and AVP were measured half-hourly for 4 hours following 1.1 ml/kg of 95% ethanol or placebo in a cross-over study. At least one week elapsed between each procedure.

SUBJECTS

Twelve healthy non-alcoholic volunteers with a wide range of background alcohol intakes.

MEASUREMENTS

Peptide hormones were measured by radioimmunoassay, cortisol by ELISA and blood ethanol by headspace gas chromatography. Results are expressed as mean +/- SEM.

RESULTS

Blood ethanol levels peaked at one hour post ethanol ingestion. Three subjects developed significant gastrointestinal (GI) side-effects, with two vomiting and one experiencing moderate to severe nausea. There was no difference between peak blood ethanol levels in the groups with and without GI side-effects (34.5 +/- 2.4 mmol/l vs 34.3 +/- 1.7 mmol/l respectively). ACTH and cortisol rose in those subjects who experienced GI side-effects (P < 0.0001 for each). The remaining subjects had a tendency for ACTH and cortisol to be higher on the placebo day. The group with GI side-effects following ethanol administration had a significant rise in AVP (P < 0.02) that was synchronous with ACTH and cortisol. No consistent alcohol related changes were seen in peripheral CRH levels, although there was a significant increase over time on both active and placebo days (P < 0.0001). In the group with no GI side-effects, AVP did not significantly fall in the first half hour following ethanol, while a significant fall did occur following placebo (P < 0.05). Plasma renin activity was, however, increased by ethanol (P < 0.05). The background alcohol intake of the group with GI side-effects was significantly lower than the group without (18 +/- 7 vs 235 +/- 51 g/week, P < 0.05), but no hormonal response was seen in two subjects with a relatively low alcohol intake (< 100 g/week) who did not experience GI side-effects.

CONCLUSION

Intoxicating levels of ethanol per se do not result in activation of the hypothalamic-pituitary-adrenal axis in humans. However, gastrointestinal side-effects induced by the ethanol do result in such activation, which appears to be mediated by AVP as the dominant ACTH secretagogue. One of the factors which influences the blood ethanol level at which GI side-effects occur appears to be background alcohol intake.

The plasma interleukin-6 and stress hormone responses to acute pyelonephritis

The relationships between the "stress hormones" corticotrophin (ACTH), vasopressin (AVP), corticotrophin releasing hormone (CRH) and cortisol, and the cytokines, interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor were studied during an acute infection. Ten patients (7 female, 3 male, age range 16-56 years) with acute pyelonephritis and normal renal function were studied during the first 72 hours following hospital admission. Peptide hormones were measured by radioimmunoassay, cortisol and cytokines by ELISA. Reference ranges for all hormones were from samples donated by 40 or more volunteers from the electoral roll. The reference data for IL-6 was obtained from 20 normal donor sera. The mean plasma IL-6, AVP and CRH concentrations on admission to hospital were significantly raised above the mean 08:00h values of the normal volunteers (p < 0.001 for AVP and CRH, p < 0.01 for IL-6), but mean plasma ACTH and cortisol were not. Mean plasma IL-6 and AVP were raised more than two standard deviations above the mean of the reference range for 72 hours, although IL-6 tended to fall after 24 hours. No change in plasma IL-1 and tumour necrosis factor was observed in three patients. The correlation between plasma IL-6 and cortisol concentrations at all sampling times and in all subjects was highly significant (p < 0.001). Significant correlations between plasma IL-6 and AVP (p < 0.005), and IL-6 and ACTH (p < 0.05) were also observed. No correlation between IL-6 and CRH could be demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma corticotrophin releasing hormone, vasopressin, ACTH and cortisol responses to acute myocardial infarction

OBJECTIVES

We assessed the magnitude and duration of the response of hypothalamic-pituitary-adrenal hormones to the stress of myocardial infarction, in the presence and absence of angiotensin converting enzyme inhibitors. In particular, we wished to analyse the interrelationships between peripheral plasma levels of corticotrophin releasing hormone (CRH), vasopressin (AVP) and adrenocorticotrophin (ACTH), and also between ACTH and cortisol, during a prolonged medical stress.

DESIGN

All hormones were measured within 6 hours of the onset of an acute myocardial infarction. Patients were randomly allocated to three different study groups according to a double blind procedure.

PATIENTS

Group 1 (10 patients) received placebo treatment, Group 2 (13 patients) received a maintenance dose of captopril 25 mg three times daily, Group 3 (11 patients) received enalapril 5 mg three times daily.

MEASUREMENTS

Peptide hormones were measured by radioimmunoassay, and cortisol by ELISA. Reference ranges for all hormones were obtained from 40 or more volunteers from the electoral roll.

RESULTS

At the start of the study, mean +/- SEM plasma AVP (27.9 +/- 4.6 pmol/l) was significantly (P < 0.001) raised above the mean for the reference range (1.82 +/- 0.09 pmol/l), and 12 patients had values > 50 pmol/l. Mean plasma cortisol (960 +/- 89.6 nmol/l) was also raised above the reference range mean (554 +/- 28 nmol/l, P < 0.001), as was mean plasma CRH (4.97 +/- 0.5 pmol/l, reference mean 1.52 +/- 0.09 pmol/l, P < 0.001). By contrast, mean ACTH (3.88 +/- 0.66 pmol/l) was significantly less than the reference mean (10.7 +/- 0.7 pmol/l, P < 0.001). During the 72-hour observation period there was a highly significant fall (P < 0.001) in plasma CRH, AVP and cortisol. By contrast, plasma ACTH rose, and the change with time of ACTH was significantly different from the fall in plasma CRH, AVP or cortisol (P < 0.001 for each comparison). No significant differences in plasma CRH, AVP, ACTH or cortisol responses to placebo, captopril or enalapril were observed.

CONCLUSIONS

Within 6 hours of a myocardial infarction, mean plasma CRH, AVP and cortisol values were very significantly raised above mean control values, while ACTH was very significantly reduced. During the 3 days following an acute myocardial infarction, plasma CRH, AVP and cortisol fell substantially, and this pattern was not influenced by angiotensin converting enzyme inhibitors. By contrast, plasma ACTH showed a significant increase with time. This suggests that the usual relationships between CRH, AVP and ACTH, and between ACTH and cortisol are disturbed in patients admitted to hospital with myocardial infarction. Maximum levels of AVP observed in 12 patients exceeded 50 pmol/l, which may be sufficiently high to interfere with tissue perfusion. It is postulated that V1 AVP receptor antagonists may have a therapeutic application in limiting infarct size.

Continuation of a case report

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Pediatric cardiology: auscultation from 280 miles away

New long-distance audio/video and data communications links among health-care facilities promise to reduce rural patients' travel time and waiting time for subspecialty consultations. To offer a satisfactory alternative to face-to-face examination, the long-distance system must meet the subspecialty's minimum criteria. For pediatric cardiology in particular, the system has to permit satisfactory cardiac auscultation. A preliminary test of remote auscultation that uses an electronic stethoscope involved two pediatric cardiologists, one listening hands-on with an acoustic stethoscope, the other listening independently at long distance with the electronic instrument. Taking the acoustic findings as the reference standard, the electronic stethoscope did not miss the one case of heart disease, correctly recommended echocardiogram follow-up in the two cases requiring it, and agreed on 80% of the murmurs' qualitative specifics. The patients' parents also indicated that the system was highly acceptable. We are following up these results with a full-scale study of the effectiveness and parental acceptance of remote auscultation.

Neonatal aortic thrombosis complicating umbilical artery catheterization: successful treatment with retroperitoneal aortic thrombectomy

A newborn infant with a history of umbilical artery catheterization had renal vascular hypertension and congestive heart failure. An abdominal ultrasound examination revealed aortic thrombosis extending from the celiac axis to the aortic bifurcation. Retroperitoneal aortic thrombectomy was performed without difficulty. The infant's hypertension and cardiac failure resolved. The retroperitoneal approach allowed excellent exposure of the aorta and avoided the postoperative gastrointestinal morbidity associated with a transperitoneal approach.

Early detection of vascular dysfunction in type I diabetes

Blood flow and transcutaneous oxygen tension was measured by venous occlusion plethysmography and a transcutaneous oxygen electrode before and after 5 min of arterial occlusion in the forearm of young adult subjects with type I (insulin-dependent) diabetes without overt evidence of angiopathy. In control subjects (n = 21), the forearm blood flow increased by greater than or equal to 2.8-fold at 30 s after ischemia. Diabetic subjects with glycosylated hemoglobin (GHb) less than or equal to 9.5% (n = 15) exhibited a blood flow response that was not statistically different from normal control subjects. Diabetic subjects with GHb greater than or equal to 12.5% (n = 23) did not exhibit an increase in the postischemic blood flow. When blood flow patterns for the first 14 diabetic subjects were examined regardless of GHb value, four patterns of response were noted: 1) normal pattern (n = 3), 2) normal postischemic rise in blood flow with a prolonged elevation (n = 3), 3) no postischemic rise (n = 4), and 4) variable baseline blood flow with a decrease in blood flow postischemia (n = 4). This approach indicated that a comparison of means obscured potentially meaningful abnormal patterns. Abnormalities in the response of the transcutaneous oxygen tension to ischemia were observed in both groups of diabetic patients, but the difference between diabetic patients in good and poor control was less obvious. We have defined an abnormal response of blood flow and transcutaneous oxygen tension to ischemia that may correlate to glycemic control and have identified several patterns of blood flow after ischemia that may be important in defining the etiology and natural history of diabetic angiopathy.

Morphometry of right ventricular papillary muscle in rat during development and regression of hypoxia-induced hypertension

Morphometric analyses of the right ventricular papillary muscle, as well as measurements of right ventricular pressure and weight, were carried out in the rat during the development and recovery of hypoxic pulmonary hypertension. Animals were divided into hypoxic and normobaric control groups. The hypoxic rats were placed in hypobaric chambers for 1, 2, and 3 wks; and after 3 wks exposure, subgroups of hypoxic rats were allowed to recover in normoxia for 1 to 9 wks. Hematocrit (HCT) and right ventricular systolic pressure (RVSP) were measured prior to sacrifice. The heart was perfused, and the right ventricle (RV) was separated from the left ventricle and septum (LV+S) and weighed. The papillary muscles were dissected and processed for ultrastructural morphometry. Results showed that HCT, RVSP, and RV weight increased in the rats during the hypoxic exposure and then gradually returned to control levels after 3 to 4 wks of normobaric recovery. The papillary muscle of the hypoxic rats showed increased volume density of interstitium, increased diameter and cross sectional area of the cardiac myocytes, reduced volume density of mitochondria, and reduced mitochondria to myofilament ratio. During normoxic recovery, these morphometric indices returned toward control values at various periods of time ranging from less than 3 wks to 9 wks. The results indicate that the adaptive ultrastructural changes of the papillary muscle in RV hypertrophy paralleled the RVSP changes, and also demonstrate the reversibility of these changes in ambient oxygen.

Effects of mixing short- and intermediate-acting insulins on absorption course and biologic effect of short-acting preparation

The effects of mixing short- and intermediate-acting insulins (Actrapid MC and Monotard MC) were studied in seven diabetic patients. On different days, 0.16 IU/kg of Actrapid and 0.24 IU/kg of Monotard were administered to each subject in separate injections and combined in the same syringe. Free-insulin curves and the biologic effect of insulin, assessed by the glucose-clamp technique, were compared. The absorption rate of regular insulin was higher when injected separately from the intermediate-acting preparation: the incremental areas of free insulin above basal levels, up to 90 min after the administration of the hormone, were 32 +/- 5 vs. 21 +/- 3 microU X ml-1 X min-1 (P less than .02). In the same period, glucose infused to sustain glycemia showed no significant differences (2.8 +/- 0.4 vs. 2.4 +/- 0.3 mg X kg-1 X min-1 after the administration of insulin in separate and combined injection, respectively). The difference in insulin profiles is not translated into a significant difference in glucose requirement. This might be a consequence of a flattening of the insulin dose-response curve due to insulin resistance of diabetic subjects. The slight delay in insulin action of Actrapid when mixed with Monotard is probably irrelevant in clinical practice.

Scanning electron microscopy of pulmonary vascular endothelium in rats with hypoxia-induced hypertension

Scanning electron microscopy was used to study the endothelial surface of the pulmonary trunk, artery, and vein in normobaric control rats as well as in rats exposed to hypobaric hypoxia for 7 and 21 days. The individual endothelial cells of the normobaric pulmonary trunk and hilar artery were flat and slightly elongated with elevated nuclear regions, and those of the intermediate-sized artery were more elongated and had more microvilli than the large arteries studied. Their endothelial cell boundaries were outlined by beaded cytoplasmic projections. The surfaces of the normobaric hilar and intermediate-sized veins were smooth and demonstrated numerous longitudinal streaks. These venous endothelial cells were elongated and their cell boundaries were outlined by low discontinuous marginal folds. Exposure to hypobaric hypoxia caused the following changes on the arterial surface: elevation of the endothelial cells; formation of microvilli-rich cell clusters; formation of hollow defects; and the attachment of leukocytes. Hypobaric hypoxia also caused the disappearance of the longitudinal streaks and the occurrence of microvilli-rich cells in the hilar veins. The endothelial surface modifications in the hypobaric rats could be related to thickening of the endothelium, intimal edema, increased intimal connective tissue, luminal invasion of leukocytes, and increased endothelial cell proliferation, known to occur in systemic arteries of hypertensive animals.

Pancreatic beta-cell function in cirrhotic patients with and without overt diabetes. C-peptide response to glucagon and to meal

To study the role of pancreatic beta-cell function in glucose intolerance and frank diabetes that sometimes develops in cirrhosis, the C-peptide response to a bolus IV injection of 1 mg of glucagon was measured in nine controls and in two groups of patients with cirrhosis. The first group comprised nine subjects with normal or high-normal fasting plasma glucose and no glycosuria; five of them had impaired glucose tolerance. The second group consisted of eight cirrhotics in whom frank diabetes had developed six to 48 months after the diagnosis of cirrhosis. They were characterized by fasting plasma glucose greater than 140 mg/dL and permanent glycosuria. No differences in the degree of liver impairment or portal-systemic shunting were observed between the two groups. Plasma glucose response to glucagon was similarly reduced in cirrhotic subjects. Basal C-peptide was high normal in patients with cirrhosis, and significantly increased in nondiabetic subjects. By contrast peak C-peptide levels and total C-peptide responses to glucagon were low normal in cirrhotics and significantly reduced in patients with cirrhosis and diabetes. In 14 patients the C-peptide response to a standard meal was also measured. It was significantly reduced in patients with cirrhosis and diabetes (six cases), as compared to cirrhotic subjects without diabetes. Peak C-peptide after IV glucagon significantly correlated with peak C-peptide after the meal (r = .927), or total C-peptide response to meal (r = .871). Impaired insulin secretion may add to insulin resistance in patients with liver cirrhosis, leading to the development of frank diabetes, characterized by fasting hyperglycemia and glycosuria.

Reduction in hypertension-induced protein synthesis in the rat pulmonary trunk after treatment with teprotide (SQ 20881)

Angiotensin II has been previously implicated as a mediator of vasoconstriction during the development of hypoxic pulmonary hypertension. The effect of angiotensin-converting enzyme inhibition with teprotide (SQ 20881) on development of pulmonary hypertension was determined by measurement of the drug's ability to modify hypertension-induced protein synthetic changes in the rat pulmonary trunk. Rats were injected with either SQ 20881 (2 mg/kg body wt every 8 hr) or saline vehicle during exposure to chronic hypoxia at 0.5 atm for either 3 or 7 days. Comparisons were made of tissue weight, absolute protein content, and in vitro synthesis of collagen and noncollagen protein of the pulmonary trunks of SQ-treated hypoxic, SQ-treated normoxic, saline-treated hypoxic, and saline-treated normoxic rats. Treatment of hypoxic rats with SQ 20881 was found to significantly decrease right ventricular pressure, tissue weight, absolute protein content, and in vitro protein synthesis after 7 days compared to saline-treated hypoxic rats. Neither right ventricular hypertrophy nor the development of polycythemia was decreased by SQ 20881 treatment.

Seasonal variations of total and free thyroid hormones in healthy men: a chronobiological study

The seasonal variations of iodothyronines and TSH serum concentrations were evaluated in 24 healthy subjects of both sexes. Using a 12 month cosine function, a significant circannual rhythm was found in T3, T4 and free T4 whose maximal values were found in September for T3, in August for T4 and in October for free T4. No significant seasonal variations in free T3 or TSH were found. Some circannual but not sinusoidal changes were found for reverse T3 and TBG. A positive linear correlation between T4, T3 and reverse T3 changes was observed, indicating that the sinusoidal oscillations of these hormones were in phase with each other. Relative weight was significantly lower in summer than in winter, though spontaneous caloric intake and physical activity did not change. A slight but significant correlation was found between relative weight and T4, free T4 and reverse T3 values measured during the period of study.

Successful treatment of fetal supraventricular tachycardia with maternal digoxin therapy

In a fetus with supraventricular tachycardia (SVT) and cardiac failure, normal sinus rhythm (NSR) was restored with maternal digoxin therapy at 26 weeks' gestation. The diagnosis of cardiac failure was based on ultrasound evidence of ascites and scalp edema. Cardiac failure was attributed to the persistent SVT. The infant remained in NSR and was delivered at 36 weeks' gestation because of persistent ascites. Intracardiac anatomy was normal. This case confirms the usefulness of prenatal ultrasound examinations in the diagnosis of fetal SVT and cardiac failure and illustrates the effectiveness and safety of transplacental digoxin therapy in the management of fetal SVT.

Insulin resistance in patients with polycystic ovaries: its relationship to body weight and androgen levels

Using a combined infusion of somatostatin, insulin and glucose, insulin resistance was assessed in vivo in two groups of females with polycystic ovaries (PCO), obese (PB-PCO) and normal weight (NO-PCO) and in two groups of matched (for age, sex and body mass index) controls (OB and NO). A steady state plasma glucose (SSPG) and insulin (SSPI) was attained after 90 min. OB-PCO and NO-PCO showed higher SSPG with respect to matched controls. The SSPG levels were related to body mass index (r = 0.69; P less than 0.001). The SSPG values were significantly correlated with the fasting insulin levels (r = 0.47; P less than 0.003). Gonadotrophin and steroid peripheral blood concentrations were also evaluated in the PCO females. A significant correlation was found between the SSPG values and the dehydroepiandrosterone sulphate levels (r = 0.46; P less than 0.05) and between the fasting insulin levels and the androstenedione concentrations (r = 0.64; P less than 0.01). Moreover, significant correlation coefficients were found between the glucose to insulin ratio and the A (r = -0.59; P less than 0.01) and the DHEA-S (r = -0.50; P less than 0.05) plasma levels. Finally, no relationship between body mass index and A or DHEA-S levels was found in PCO females considered as a group. We conclude that insulin resistance is present in females with PCO and it is mainly due to the presence of obesity, but other factors such as androgen levels, probably of adrenal sources, must be considered as a cause.

Clinical application of the 24-H urinary C-peptide excretion rate and its relationship to metabolic control in diabetics

In this study, we evaluated in normal subjects, insulin-dependent (IDD) and non-insulin-dependent (NIDD) diabetics, the diurnal urinary C-peptide excretion rate (CPR-U) and its relationship to serum C-peptide concentration and glucose:C-peptide molar ratio, and to the common parameters of metabolic control. The CPR-U (and CPR-U/g creatinine) were significantly lower in IDD and higher in NIDD compared to control subjects. Moreover, a good and significant correlation with serum C-peptide concentrations and the glucose:C-peptide ratio in diabetic subjects as well as in controls and diabetics considered together was found. A slight but significant correlation was present in diabetic subjects between CPR-U and body mass index (r = 0.45), 24-h glycosuria (r = 0.36), HbA1 levels (r = 0.31), post-prandial glucose concentrations (r = 0.26) and per cent glucose variation after each meal (r = 0.34). No differences were found in CPR-U and the degree of metabolic control between obese and non-obese NIDD. In conclusion, CPR-U may be a useful and simple method of defining the secretory activity of the B-cell. Metabolic control in diabetics is slightly correlated to the degree of B-cell function as evaluated by the diurnal excretion rate of C-peptide in urine.

Relationships between iodothyronine peripheral metabolism and ketone bodies during hypocaloric dietary manipulations

Relationships between iodothyronine and metabolic substrate metabolism during undernutrition were evaluated in four normal subjects who fasted for 48h (Group I) and in four groups (II to V) of obese patients who underwent selective dietary manipulations: 360 calories [carbohydrate (CHO) 40 g/day]; 800 calories containing respectively 19 g/day - ketogenic - (K) and 112 g/day - non ketogenic - (NK) of CHO; and a step-diet programme (during which total calories were progressively reduced from 2500 to 500). Serum T3 levels decreased significantly and constantly during fasting, 360 and 800 K studies, and transiently during the 800 NK diet. During the step-diet programme, a significant fall was found only when 1250 K or less were given. Conversely, serum reverse T3 rose significantly and constantly during 360 and 800 K diets, while a transient increase was found during the 800 NK diet. During the step-diet programme reverse T3 rose only when 750 calories were given. Ketogenesis developed in all studies but one (800 NK), and in the step-diet programme significantly below the 1000 calorie step. Other substrate modifications in each study were also evaluated. Serum T3 levels showed a significant correlation with ketone bodies (KB) in all the ketogenic studies, while no correlation was found in non ketogenic study (800 NK). During the step-diet programme ketone bodies and iodothyronine modifications appeared to be related to the amount of calories. Based on these results, we suggest a relationship between the dietary-induced modifications of iodothyronine metabolism and the development of ketogenesis.