Insulin resistance associated with maternally inherited diabetes and deafness

Maternally inherited diabetes and deafness (MIDD) is a form of diabetes associated with mutation of mitochondrial DNA (mtDNA) that occurs in 1% to 2% of individuals with diabetes. Understanding the clinical course and abnormalities in insulin secretion and action in affected individuals should allow better understanding of how this genetic defect alter glucose metabolism. We report the clinical course of three individuals with mtDNA mutations and deafness. Subjects no. 1 and 2 had diabetes not yet requiring insulin therapy, and subject no. 3, the son of subject no. 2, had normal glucose tolerance. Defective oxidative phosphorylation (OXPHOS) based on OXPHOS enzymology of skeletal muscle biopsy of subjects no. 1 and 2 showed activity of less than 5% of the tolerance level in complex III for subject no. 1 and in complexes I, I + III, and IV for subject no. 2. Assessing insulin secretion using insulin response to intravenous glucose and insulin sensitivity based on minimal model analysis of an insulin-modified frequently sampled intravenous glucose tolerance test (FSIGT), first-phase insulin secretion was abnormal in subjects no. 1 and 2 and normal in subject no. 3 (AUC, 57, 93, and 1,235 pmol/L, respectively). In contrast, all three subjects had low insulin sensitivity indices (0.04, 0.14, and 0.27 x 10-4 x min/pmol/L, respectively). Subject no. 2, who underwent three FSIGT studies over a 16-month interval, showed transient improvement in insulin release in response to modification of diet and exercise (first-phase insulin AUC, 57 pmol/min v 287 pmol/min 10 months later; fasting insulin, 97 pmol/L v 237 pmol/L 10 months later), but by 16 months, first-phase insulin release and fasting insulin had decreased (AUC, 64 and 136 pmol/L, respectively) despite higher fasting glucose. We conclude that in our subjects with MIDD, insulin resistance is present and appears to precede defects in insulin release.

Changes in intracellular concentration of amino acids in human saphenous vein during preparation for coronary artery bypass grafting

OBJECTIVES

Earlier research on human skeletal and cardiac muscle has shown a fall in the intracellular free amino acid pool, particularly the non-essential amino acids, during surgery. Surgical preparation of the human saphenous vein for coronary artery by pass grafting has been shown to provoke metabolic damage and may therefore induce changes in cellular amino acids which may have long-term implications for the performance of the grafted vein. This work investigates the hypothesis that surgical preparation of saphenous vein induces changes in amino acids.

METHODS

Changes in the intracellular free amino acid pool were monitored, using high-performance liquid chromatography (HPLC), in both freshly isolated and surgically prepared human saphenous veins during coronary artery bypass grafting. In order to asses the extent of metabolic damage incurred by surgical preparation, adenosine triphosphate (ATP) levels were also measured.

RESULTS

A substantial fall in intracellular free amino acid was associated with surgical preparation of human saphenous vein for coronary artery bypass grafting (190.8 +/- 25 to 106 +/- 18 mumol.g-1 protein, n = 10, P < 0.05). Although the fall was seen in most amino acids detected, it was marked and statistically significant (P < 0.05) for taurine (30.6 +/- 3.1 to 9.0 +/- 2.2 mumol.g-1 protein), glutamate (43.6 +/- 5.6 to 18.2 +/- 4.5 mumol.g-1 protein), glutamine (12.8 +/- 1.6 to 3.3 +/- 1.2 mumol.g-1 protein) and asparagine (9.6 +/- 1.6 to 4.1 +/- 1.0 mumol.g-1 protein). The fall in tissue taurine which would be largely due to transport showed a strong positive correlation with the fall seen in glutamate, glutamine and asparagine. ATP levels significantly decreased as a result of surgical preparation (279 +/- 44 to 96 +/- 21 nmol.g-1 wet weight, P < 0.05). The fall in ATP was accompanied by an increase in alanine/glutamate ratio which may reflect increased glutamate-alanine transaminase activity and therefore metabolic changes.

CONCLUSIONS

The metabolic damage associated with surgical preparation of human saphenous vein for coronary artery bypass grafting is accompanied by a fall in the intracellular free amino acid pool which is marked and statistically significant for glutamate, taurine, glutamine and asparagine. The fall is likely to be due to transport metabolism may also contribute. This may have important implications for the functional recovery of the grated vein.

Direct evidence that the POU family transcription factor Oct-2 represses the cellular tyrosine hydroxylase gene in neuronal cells

The POU family transcription factor Oct-2 was originally identified in B lymphocytes but has been shown to be expressed in neuronal cells, although it is absent in most other cell types. Cotransfection of Oct-2 expression vectors into nonneuronal cells with a tyrosine hydroxylase promoter/reporter plasmid suggests that Oct-2 can repress this promoter in this artificial situation. Here we report that reduction of endogenous Oct-2 levels in a neuronal cell line by an antisense approach results in an increase in endogenous tyrosine hydroxylase levels. In contrast, the level of the neuronal marker protein PGP9.5 remains unchanged in the antisense lines whereas that of the neuronal nitric oxide synthase decreases. Hence, the tyrosine hydroxylase gene is a natural target for repression by Oct-2 in neuronal cells. The significance of this effect is discussed in terms of the processes that regulate tyrosine hydroxylase gene expression and the role of Oct-2 in neuronal cells.

U.S. apartheid and the spread of AIDS to the suburbs: a multi-city analysis of the political economy of spatial epidemic threshold

We compare mechanisms of AIDS diffusion at the county level from five U.S. central city epicenters into their associated metropolitan regions. Four of the five show an expanding 'hollowed out' center of physically and socially devastated, politically and economically abandoned high density minority neighborhoods, surrounded by rings of relatively affluent majority suburban populations. From these centers AIDS diffuses into the suburbs as a single, spatially extended disease ecosystem. The exception, San Francisco, has not yet experienced the 'hollowing out' process and is, we conclude, a major AIDS epicenter markedly less coupled to its suburbs because of that fact. This may constitute one of the few empirical observations of spatial threshold in epidemiology. Our empirical results contradict the conclusions of a recent National Research Council report that AIDS will be largely confined within marginalized urban populations. In reality U.S. urban apartheid, particularly its continuing disruption of minority social structures, has markedly accelerated the diffusion of AIDS into suburban communities. A widespread program of reform, which rebuilds minority physical and social community structures within both city and suburb, is an essential, but largely unrecognized, component to any serious strategy for the control of AIDS in the United States.

Quantitative and qualitative analysis of polyethylene wear particles in synovial fluid of patients with total knee arthroplasty. A preliminary report

Synovial fluid from 13 knees undergoing revision total knee arthroplasty was subjected to chemical digestion and ultrafiltration. Scanning electron microscopy was used to visualize high-density polyethylene particles filtered from the fluid, and the images were analyzed using digital imaging software. This data were correlated with polyethylene wear patterns seen at the time of revision surgery. Patients' prostheses with gross polyethylene wear were differentiated from those with surface deformation and burnishing. The knees had been in situ for periods ranging from 3 to 112 months, and included 6 different prosthetic designs. The average area of the polyethylene particles measured ranged from 41 to 701 mu 2, and the total number of particles identified for each sample ranged from 38 to 279 mu 2. The largest particle identified had a surface area of 17,500 mu 2. Using the fluid volume analyzed, the particle area per milliliter of synovial fluid examined was calculated, and values ranged from 6.22 x 10(4) to 2.06 x 10(6) mu 2/ml. Visualization of high-density polyethylene using scanning electron microscopy allows greater resolution of morphologic detail than is possible with routine histologic examination using light microscopy. There were trends toward increasing particle size and total particle area in patients with gross polyethylene wear. The area of high-density polyethylene per milliliter of fluid in patients with gross wear was found to be statistically greater than that of patients without gross wear (p = 0.047). This technique offers a potentially valuable method of evaluating the status of high-density-polyethylene bearing surfaces in situ using a noninvasive technique.

Will AIDS be contained within U.S. minority urban populations?

Recent empirical research, and a simple stochastic modeling exercise, suggest that affluent suburban communities are at increased risk for the diffusion of HIV from present inner city epicenters, while the 'core group' construct of sexually transmitted disease theory suggests, somewhat counter-intuitively, that the hypercongregated and strongly self-interacting nature of affluent heterosexual elites in the U.S. places them at significant and increasing risk as well. In turn, a growing body of work strongly associates high HIV prevalence in minority urban populations with the processes of coupled physical and social disintegration which have produced the now-common and politically-generated 'hollowed out' pattern of U.S. cities. We conclude that a return to the principles of the Great Reform Movement, which first brought public health and public order to U.S. urban areas, is a necessary, but at present largely unrecognized, component to any successful national program to control AIDS in the United States, and particularly to stem the diffusion of HIV into heterosexual populations outside present diseases epicenters.

Metabolism of [3H] 17 beta-dihydroequilin and [3H] 17 beta-dihydroequilin sulfate in normal postmenopausal women

The metabolism of 17 beta-dihydroequilin and 17 beta-dihydroequilin sulfate was investigated after intravenous administration of [3H] 17 beta-dihydroequilin and [3H] 17 beta-dihydroequilin sulfate to postmenopausal women. Urine was collected for 3 days and 46.2 +/- 10.5% and 54.5 +/- 8.7% of the injected dose of [3H] 17 beta-dihydroequilin and [17 beta-3H]dihydroequilin sulfate was excreted in the urine respectively. The estrogens present in urine were extracted and fractionated into unconjugated, sulfate, and glucuronide conjugated forms. With both precursors, the major amount (63-64%) of metabolites were excreted in the urine conjugated with glucuronic acid. From the unconjugated, sulfate, and glucuronide fraction, 17 beta-dihydroequilenin, 17 beta-dihydroequilin, equilenin, and equilin were isolated. The conversions with both precursors were similar and 17 beta-dihydroequilenin was the major metabolite isolated from all three fractions; however, the highest levels of all four metabolites were present in the glucuronide fraction. Along with these identifiable metabolites, a large amount (51-81%) of radioactivity was present in the form of metabolites which are more polar than any of the known ring-B unsaturated estrogens. These appear to be polyhydroxy 17 beta-reduced ring-B unsaturated estrogens which remain to be identified. The in-vivo formation of equilenin and 17 beta-dihydroequilenin indicates the presence of the enzyme 6.8(9) steroid dehydrogenase in humans.

The resurgence of tuberculosis in New York City: a mixed hierarchically and spatially diffused epidemic

For New York City from 1978 to 1990, plotting the 3-year running averages of citywide new tuberculosis cases against the middle year yielded an S-shaped curve, with the inflection point at 1983 between early slow and late rapid rise. The inflection in the S curve appears to be associated with hierarchical establishment of secondary epicenters, and the phase of rapid rise in new cases seems to be associated with spatial diffusion from both the primary and secondary epicenters.

Ultraviolet/ozone cleaning of carbon-contaminated optics

It is shown that ozone generated by UV light can be used to clean carbon-contaminated synchrotronradiation optics.

Nurses' ability to achieve hyperinflation and hyperoxygenation with a manual resuscitation bag during endotracheal suctioning

OBJECTIVE

To examine nurses' ability to deliver 1.5 times the ventilated tidal volume at 100% FIO2 with a manual resuscitation bag during endotracheal suctioning.

DESIGN

Prospective, descriptive.

SETTING

Six adult critical care units in a large university-affiliated medical center.

SUBJECTS

One hundred nurses randomly selected from the six adult intensive care units.

OUTCOME MEASURES

Nurses' manual resuscitation bag delivery of tidal volume and oxygen, as well as bagging rate, number of breaths delivered, and number of suction catheter passes performed. Patients' heart rate, mean arterial pressure, and arterial oxygen saturation.

RESULTS

The mean FIO2 delivered was 0.71 (range 0.24 to 0.97). Oxygen liter flow and nurses' delivered minute ventilation predicted 24% of the variance in FIO2 delivered. Mean bagging rate was 31 compressions per minute. The mean volume per breath delivered was 626 cc, which resulted in achievement of 57% of the standard (1128 cc). Volume achieved was related to patient lung compliance, but not related to nurses' experience, unit of employment, hand strength, or size.

CONCLUSIONS

Nurses observed were unable to meet the standard for volume or oxygen delivery. However this did not affect the patient's heart rate, mean arterial pressure, or SaO2.

Comparative biodisposition and metabolism of 14C-(+/-)-fenfluramine in mouse, rat, dog and man

1. The comparative metabolism of fenfluramine was investigated in mouse, rat, dog and man following a single oral dose of 14C-(+/-)-fenfluramine hydrochloride (1 mg/kg), and also in rat after eight consecutive 12-h subcutaneous doses (24 mg/kg). 2. Main route of excretion of radioactivity in all species and at all doses was into urine (> 80%), with only minor amounts of radioactivity found in faeces. 3. From all species examined a total of 11 metabolites were observed in urine and plasma by t.l.c. and h.p.l.c. analysis and no metabolite was present in the plasma which was not present in urine. 4. All species dealkylate fenfluramine to the active metabolite norfenfluramine, to a relative greater or lesser extent, with plasma metabolic ratios (norfenfluramine/fenfluramine) showing inter-animal variation (rat >> dog >> mouse = man). 5. These differences are due to the efficient deamination of both compounds to polar inactive metabolites in man, with less dealkylation and lower plasma levels of norfenfluramine compared with the other species studied. 6. In conclusion, major species differences in the metabolism of (+/-)-fenfluramine, both qualitative and quantitative were observed, and no one species had a similar metabolic profile to that found in man.