Doppler ultrasound (pre- and post-contrast enhancement) for detection of recurrent stenosis in stented renal arteries: preliminary results

The purpose of the present paper was to assess whether conventional renal Doppler ultrasound and the commonly used parameters of peak systolic velocity and renal aortic ratio may be an appropriate modality for the follow-up of renal artery stents. A total of 19 arteries in 15 patients was examined with both renal Doppler ultrasound and angiography for the presence or absence of recurrent renal artery stenosis. Disease was considered present on angiography if the arterial diameter was more than 60% stenotic. Doppler criteria for stenosis were either a peak systolic velocity of > 180 cm/s or a renal aortic ratio of > 3.0. Echo enhancement with Levovist (Schering, Berlin, Germany) was used if studies were technically unsuccessful or to improve diagnostic confidence. Renal Doppler ultrasound detected 100% of renal artery stenoses. The specificity was 75%, the positive predictive value was 67% and the negative predictive value was 100%. Echo enhancement improved the technical success rate from 89 to 95% and also increased diagnostic confidence in six examinations. The present limited study suggests that similar renal Doppler parameters as used for the study of unstented renal arteries may be applied to the examination of renal arteries with renal stents in situ. It therefore suggests that Doppler ultrasound may provide an adequate non-invasive means of renal artery stent follow-up, particularly when combined with echo-enhancing agents. Further study is warranted to confirm these initial conclusions.

Using Doppler sonography to reveal renal artery stenosis: an evaluation of optimal imaging parameters

OBJECTIVE

The aim of this study was to determine the accuracy of direct and indirect parameters for the diagnosis of renal artery stenosis and to determine the most useful thresholds for these parameters.

SUBJECTS AND METHODS

One hundred twenty-five arteries in 63 patients were examined with renal Doppler sonography and angiography for the presence or absence of renal artery stenosis. Arteries were considered stenosed on angiography if there was a diameter reduction of greater than 60%. Renal Doppler sonographic measures of peak systolic velocity, renal aortic ratio, acceleration time, and acceleration were recorded and compared with the angiographically determined presence or absence of disease.

RESULTS

Doppler examination was technically successful in 87% of kidneys and 76% of patients. Receiver operating characteristic analysis showed the optimal peak systolic velocity threshold to be 180 cm/sec and the optimal renal aortic ratio threshold to be 3.0. An acceleration time greater than 70 msec and an acceleration less than 300 cm/sec2 yielded sensitivities of 41% and 56%, respectively, and specificities of 85% and 62%, respectively. Combining a renal aortic ratio of greater than 3.0 or peak systolic velocity greater than 180 cm/sec provided the best combination of parameters with a sensitivity and sensitivity at 85% and 76%, respectively.

CONCLUSION

The most accurate use of parameters was found to be a combination of either peak systolic velocity greater than 180 cm/sec or renal aortic ratio greater than 3.0. Indirect parameters were not found to be useful in predicting the presence or absence of renal artery stenosis.

Fluoride release of glass ionomer-based luting cements in vitro

STATEMENT OF PROBLEM

There is considerable variation in generic formulation and in reported fluoride release from resin-modified glass ionomer luting cements.

PURPOSE

This study compared fluoride release from 2 generically similar resin-modified glass ionomer luting cements (Vitremer and Advance) with release from 2 conventional glass ionomer luting cements (Ketac-Cem and Fuji I).

MATERIAL AND METHODS

Ten specimen disks of each of the 4 luting cements were fabricated and immersed in deionized water in individual polystyrene jars. The jars were stored in a humidor at 37 degrees C between test periods. At the same time each day, for 28 days, fluoride release from each specimen disk was measured in parts per million by testing the storage water.

RESULTS

The 4 luting cements tested showed an initial high concentration of fluoride release during the first week, followed by a gradual decrease over the study period. Vitremer luting cement demonstrated the greatest mean cumulative fluoride release in parts per million over the study period (198), followed by Fuji I (140), Ketac-Cem (110), and Advance (99) luting cements.

CONCLUSIONS

Resin-modified glass ionomer luting cements showed fluoride release comparable to the conventional glass ionomer luting cements. Vitremer luting cement released more fluoride over the 28-day period than the other cements.

Decreased plasma leptin levels in lean and obese Zucker rats after treatment with the serotonin reuptake inhibitor fluoxetine

Leptin inhibits feeding, stimulates thermogenesis and decreases body weight. Serotonin reduces food intake when injected into the hypothalamus and may interact with other neurotransmitters in the control of appetite. We therefore investigated the effects of the serotonergic drug fluoxetine, which inhibits serotonin reuptake, on food intake and plasma leptin levels in lean and obese Zucker rats. Fluoxetine significantly reduced food intake in lean and obese rats, both acutely after a single injection (10 mg/kg) and during continuous subcutaneous infusion (10 mg/kg/day for 7 days). Plasma leptin levels were reduced after both 4 hours and 7 days of fluoxetine administration in lean and after 7 days in fatty rats (all p<0.01). We have previously suggested that serotonin may decrease food intake by inhibiting neuropeptide Y neurones, and we further suggest that it also inhibits leptin, possibly by an effect on white adipose tissue.

The effect of moxonidine on feeding and body fat in obese Zucker rats: role of hypothalamic NPY neurones

The antihypertensive agent moxonidine, an imidazoline Ii-receptor agonist, also induces hypophagia and lowers body weight in the obese spontaneously hypertensive rat, but the central mediation of this action and the neuronal pathways that moxonidine may interact with are not known. We studied whether moxonidine has anti-obesity effects in the genetically-obese and insulin-resistant fa/fa Zucker rat, and whether these are mediated through inhibition of the hypothalamic neuropeptide Y (NPY) neurones. Lean and obese Zucker rats were given moxonidine (3 mg kg(-1) day(-1)) or saline by gavage for 21 days. Moxonidine decreased food intake throughout by 20% in obese rats (P<0.001) and by 8% in lean rats (P<0.001), and reduced weight gain that final body weight was 15% lower in obese (P<0.001) and 7% lower in lean (P<0.01) rats than their untreated controls. Plasma insulin and leptin levels were decreased in moxonidine-treated obese rats (P<0.01 and P<0.05), but unchanged in treated lean rats. Uncoupling protein-1 gene expression in brown adipose tissue was stimulated by 40-50% (P< or =0.05) in both obese and lean animals given moxonidine. Obese animals given moxonidine showed a 37% reduction in hypothalamic NPY mRNA levels (P = 0.01), together with significantly increased NPY concentrations in the paraventricular nucleus (P<0.05), but no changes in the arcuate nucleus or other nuclei; this is consistent with reduced NPY synthesis in the arcuate nucleus and blocked release of NPY in the paraventricular nucleus. In lean animals, moxonidine did not affect NPY levels or NPY mRNA. The hypophagic, thermogenic and anti-obesity effects of moxonidine in obese Zucker rats may be partly due to inhibition of the NPY neurones, whose inappropriate overactivity may underlie obesity in this model.

Long-term survival characteristics of 832 resin-retained bridges and splints provided in a post-graduate teaching hospital between 1978 and 1993

The clinical performance of 832 resin-retained bridges and splints provided in the adult fixed prosthodontic clinic of a post-graduate teaching hospital was reviewed. Recall data was available for 58.4% of cases and the median survival was 7 years and 10 months. Analysis of clinical variables influencing survival revealed that the design and retainer coverage were significant factors. The experience of the operator carrying out treatment also had a pronounced effect which was not readily explained in terms of the distribution of other significant factors. Resin-retained restorations made with minimal tooth preparation are shown to be capable of extended clinical service and their failure rarely resulted in adverse consequences for the patient. Patient satisfaction with their treatment was reportedly high.

Divergent effects of intracerebroventricular and peripheral leptin administration on feeding and hypothalamic neuropeptide Y in lean and obese (fa/fa) Zucker rats

Leptin inhibits feeding and decreases body weight. It may act partly by inhibiting hypothalamic neurons that express neuropeptide Y, a powerful inducer of feeding and obesity. These neuropeptide Y neurons express the Ob-Rb leptin receptor and are overactive in the fatty (fa/fa) Zucker rat. The fa mutation affects the extracellular domain of the leptin receptor, but its impact on leptin action and neuropeptide Y neuronal activity is not fully known. We compared the effects of three doses of leptin given intracerebroventricularly and three doses of leptin injected intraperitoneally on food intake and hypothalamic neuropeptide Y mRNA, in lean and fatty Zucker rats. In lean rats, 4-h food intake was reduced in a dose-related fashion (P<0.01) by all intracerebroventricular leptin doses and by intraperitoneal doses of 300 and 600 microg/kg. Neuropeptide Y mRNA levels were reduced by 28% and 21% after the highest intracerebroventricular and intraperitoneal doses respectively (P<0. 01 for both). In fatty rats, only the highest intracerebroventricular leptin dose reduced food intake (by 22%; P<0. 01). Neuropeptide Y mRNA levels were 100% higher in fatty rats than in lean animals, and were reduced by 18% (P<0.01) after the highest intracerebroventricular leptin dose. Intraperitoneal injection had no effect on food intake and neuropeptide Y mRNA. The fa/fa Zucker rat is therefore less sensitive to leptin given intracerebroventricularly and particularly intraperitoneally, suggesting that the fa mutation interferes both with leptin's direct effects on neurons and its transport into the central nervous system. Obesity in the fa/fa Zucker rat may be partly due to the inability of leptin to inhibit hypothalamic neuropeptide Y neurons.

Euglycaemic hyperinsulinaemia does not affect gastric emptying in type I and type II diabetes mellitus

Hyperglycaemia slows gastric emptying in both normal subjects and patients with diabetes mellitus. The mechanisms mediating this effect, particularly the potential role of insulin, are uncertain. Hyperinsulinaemia has been reported to slow gastric emptying in normal subjects during euglycaemia. The purpose of this study was to evaluate the effect of euglycaemic hyperinsulinaemia on gastric emptying in Type I (insulin-dependent) and Type II (noninsulin-dependent) diabetes mellitus. In six patients with uncomplicated Type I and eight patients with uncomplicated Type II diabetes mellitus, measurements of gastric emptying were done on 2 separate days. No patients had gastrointestinal symptoms or cardiovascular autonomic neuropathy. The insulin infusion rate was 40 mU x m(-2) x min(-1) on one day and 80 mU x m(-2) x min(-1) on the other. Gastric emptying and intragastric meal distribution were measured using a scintigraphic technique for 3 h after ingestion of a mixed solid/liquid meal and results compared with a range established in normal volunteers. In both Type I and Type II patients the serum insulin concentration had no effect on gastric emptying or intragastric meal distribution of solids or liquids. When gastric emptying during insulin infusion rates of 40 mU x m(-2) x min(-1) and 80 mU x m(-2) x min(-1) were compared the solid T50 was 137.8+/-24.6 min vs. 128.7+/-24.3 min and liquid T50 was 36.7+/-19.4 min vs. 40.4+/-15.7 min in the Type I patients; the solid T50 was 94.9+/-19.1 vs. 86.1+/-10.7 min and liquid T50 was 21.8+/-6.9 min vs. 21.8+/-5.9 min in the Type II patients. We conclude that hyperinsulinaemia during euglycaemia has no notable effect on gastric emptying in patients with uncomplicated Type I and Type II diabetes; any effect of insulin on gastric emptying in patients with diabetes is likely to be minimal.

Comparable changes in synaptic dopamine induced by methylphenidate and by cocaine in the baboon brain

Though the blockade of dopamine transporters (DAT) is associated with cocaine's and methylphenidate's reinforcing effects, it is the stimulation of dopamine (DA) receptors, achieved by increases in synaptic DA, that enables these effects to occur. Positron emission tomography (PET) and [11C]raclopride were used to assess the levels of occupancy of DA D2 receptors by dopamine achieved by doses of cocaine or methylphenidate previously documented to block over 70% of DAT. Studies were performed in five baboons using a paired scan protocol designed to measure DA D2 receptor availability (Bmax/Kd) at baseline conditions and after intravenous administration of either cocaine or methylphenidate. Cocaine (1-2 mg/kg) or methylphenidate (0.5 mg/kg) administered 5 min prior to [11C]raclopride decreased Bmax/Kd by 29+/-3% and 32 + 4%, respectively. Smaller reductions in Bmax/Kd (13% for cocaine given 30 min before [11C]raclopride and 25+/-10% for methylphenidate given 40 min before [11C]raclopride) were seen with longer periods between drug and radioligand. These observations are consistent with the slower striatal clearance kinetics of [11C]methylphenidate than [1C]cocaine observed in previous PET experiments and with the approximately twofold higher potency of methylphenidate than cocaine in in vitro experiments. Though the elevation of synaptic DA induced by >70% occupancy of DAT by these drugs lead to a modest increase in occupancy of D2 receptors (25-30%), further studies are required to assess if this is an underestimation because of differences in D2 receptor binding kinetics between raclopride and DA.

Congenital hypothyroidism screening in Oklahoma: a change in follow-up recommendations for 1999

Effective January 1999, the Newborn Metabolic Disorder Screening Follow-up Program of the Oklahoma State Department of Health will no longer track hypothyroidism screen results of one abnormal T4 with normal TSH result. The Oklahoma State Department of Health Newborn Metabolic Disorder Screening Program (NMDSP) began screening for congenital hypothyroidism (CH) in 1979 and has subsequently identified 159 affected newborns. In 1997, Oklahoma had 46,740 live births, 51,431 specimens submitted to NMDSP Laboratory for screening, 1,302 infants identified with an abnormal thyroid screen, and 11 infants diagnosed with CH with an average treatment age of 23.2 days (see Table 1). The NMDSP identifies an average of 14 CH cases each year. The pediatric health care provider can anticipate that in his/her practice, one out of 64 infants will be identified with an abnormal T4 with normal TSH result, and one out of 82 will be identified with an abnormal TSH value. In summary, one out of 36 infants will have some degree of abnormality on the thyroid screen.

Preoperative screening for genetic abnormalities in men with nonobstructive azoospermia before testicular sperm extraction

PURPOSE

Men with nonobstructive azoospermia may be treated with testicular sperm extraction and assisted reproduction. However, in men with severely impaired spermatogenesis genetic anomalies may be a cause of low sperm production. We present the results of genetic screening of men with nonobstructive azoospermia who are testicular sperm extraction candidates.

MATERIALS AND METHODS

Genetic evaluation was performed in a sequential series of 190 men with nonobstructive azoospermia who were candidates for testicular sperm extraction, including standard peripheral karyotypic analysis and detailed polymerase chain reaction based evaluation of the Y chromosome. All men found to harbor genetic defects were referred for genetic counseling.

RESULTS

Of the 190 patients 33 (17%) had genetic abnormalities. Of the 101 men who underwent karyotyping 21 (21%) had cytogenetic abnormalities, including 13 with Klinefelter's syndrome. Of the 183 men who underwent Y chromosome partial deletion analysis defects were detected in 17 (9%). Five men had karyotypic anomalies as well as evidence of partial Y chromosome deletions on polymerase chain reaction based analysis. Genetic counseling was done in 31 men with defects before testicular sperm extraction. Knowledge of the specific genetic defect resulted in a change of clinical management in 7 of the 33 couples (21%) in which the man had a genetic abnormality.

CONCLUSIONS

These results indicate that preoperative genetic screening is important in men with nonobstructive azoospermia who are candidates for testicular sperm extraction with intracytoplasmic sperm injection. Genetic testing provides men with reassuring etiological information regarding the infertile condition as well as a means to assess the risk of passing infertility traits to male offspring. It allows specific preimplantation genetic testing of embryos during assisted reproduction to minimize the risk of transmitting genetic defects to offspring.

The development of overt diabetes in young Zucker Diabetic Fatty (ZDF) rats and the effects of chronic MCC-555 treatment

1. Young (6-week-old) pre-diabetic Zucker Diabetic Fatty (ZDF) rats displaying impaired glucose tolerance (IGT), moderate hyperglycaemia and hyperinsulinaemia were treated with the novel thiazolidinedione, MCC-555, for 28 days, during which time beta-cell failure and progression to overt diabetes occurs. 2. Treated ZDF rats exhibited consistently lower blood glucose levels than vehicle-treated diabetic controls, with a delayed rise and lower plateau levels. MCC-555 maintained plasma insulin levels throughout the treatment period, whereas these fell by 40% in untreated ZDF rats. 3. The rise in body weight was maintained in MCC-555-treated rats, whereas vehicle-treated rats exhibited blunted body weight gain after 8 weeks of age. Daily food intake was higher in diabetic, as compared to non-diabetic rats, but treatment did not modify food intake in diabetic rats. Water intake was lower in treated ZDF rats, concomitant with lowering of blood glucose. 4. The hyperinsulinaemic-euglycaemic clamp technique was applied to all rats after treatment to examine the effects of MCC-555 on insulin sensitivity. The glucose infusion rate to maintain normoglycaemia was lower in diabetic than in non-diabetic rats, demonstrating reduced glucose entry into insulin-sensitive tissues in diabetic rats. Increased glucose infusion rates were required to maintain euglycaemia in treated diabetic rats, demonstrating increased insulin sensitivity in these animals. 5. In conclusion, chronic MCC-555 treatment of young ZDF rats displaying IGT attenuates the development of overt diabetes through improved insulin sensitivity and maintenance of beta-cell function. MCC-555 may thus be beneficial in humans with IGT, to prevent or delay the progression of diabetes.

An acute dose of nicotine does not inhibit MAO B in baboon brain in vivo

Tobacco smoke exposure has been shown to inhibit brain and platelet MAO B in animals and in humans. Though the mechanism(s) responsible for MAO B inhibition are not known, studies in rodents have shown that nicotine administration does not inhibit brain MAO B. In this study we investigated whether brain MAO B is also unaffected by nicotine in the living primate. Brain MAO B was measured with positron emission tomography (PET) and deuterium substituted [11C]L-deprenyl ([11C]L-deprenyl-D2) in three baboons at baseline and 5 minutes after the injection of (-)-nicotine (0.3 mg administered intravenously). A three-compartment model was used to calculate the plasma to brain transfer constant K1 which is related to blood flow, and lambda k3, which is a function of the concentration of catalytically active MAO B molecules. Nicotine administration did not produce significant changes in either of these parameters. This study in living baboons confirms previous studies in rodents and solidifies the notion that other mechanisms for MAO B inhibition observed in smokers need to be considered.