Diabetic mitochondria are resistant to palmitoyl CoA inhibition of respiration, which is detrimental during ischemia.

The bioactive lipid intermediate palmitoyl CoA (PCoA) can inhibit mitochondrial ADP/ATP transport, though the physiological relevance of this regulation remains unclear. We questioned whether myocardial ischemia provides a pathological setting in which PCoA regulation of ADP/ATP transport would be beneficial, and secondly, whether the chronically elevated lipid content within the diabetic heart could make mitochondria less sensitive to the effects of PCoA. PCoA acutely decreased ADP-stimulated state 3 respiration and increased the apparent Km for ADP twofold. The half maximal inhibitory concentration (IC50 ) of PCoA in control mitochondria was 22 µM. This inhibitory effect of PCoA on respiration was blunted in diabetic mitochondria, with no significant difference in the Km for ADP in the presence of PCoA, and an increase in the IC50 to 32 µM PCoA. The competitive inhibition by PCoA was localised to the phosphorylation apparatus, particularly the ADP/ATP carrier (AAC). During ischemia, the AAC imports ATP into the mitochondria, where it is hydrolysed by reversal of the ATP synthase, regenerating the membrane potential. Addition of PCoA dose-dependently prevented this wasteful ATP hydrolysis for membrane repolarisation during ischemia, however, this beneficial effect was blunted in diabetic mitochondria. Finally, using 31 P-magnetic resonance spectroscopy we demonstrated that diabetic hearts lose ATP more rapidly during ischemia, with a threefold higher ATP decay rate compared with control hearts. In conclusion, PCoA plays a role in protecting mitochondrial energetics during ischemia, by preventing wasteful ATP hydrolysis. However, this beneficial effect is blunted in diabetes, contributing to the impaired energy metabolism seen during myocardial ischemia in the diabetic heart.

Megaesophagus in a line of transgenic rats: a model of achalasia.

Megaesophagus is defined as the abnormal enlargement or dilatation of the esophagus, characterized by a lack of normal contraction of the esophageal walls. This is called achalasia when associated with reduced or no relaxation of the lower esophageal sphincter (LES). To date, there are few naturally occurring models for this disease. A colony of transgenic (Pvrl3-Cre) rats presented with megaesophagus at 3 to 4 months of age; further breeding studies revealed a prevalence of 90% of transgene-positive animals having megaesophagus. Affected rats could be maintained on a total liquid diet long term and were shown to display the classic features of dilated esophagus, closed lower esophageal sphincter, and abnormal contractions on contrast radiography and fluoroscopy. Histologically, the findings of muscle degeneration, inflammation, and a reduced number of myenteric ganglia in the esophagus combined with ultrastructural lesions of muscle fiber disarray and mitochondrial changes in the striated muscle of these animals closely mimic that seen in the human condition. Muscle contractile studies looking at the response of the lower esophageal sphincter and fundus to electrical field stimulation, sodium nitroprusside, and L-nitro-L-arginine methyl ester also demonstrate the similarity between megaesophagus in the transgenic rats and patients with achalasia. No primary cause for megaesophagus was found, but the close parallel to the human form of the disease, as well as ease of care and manipulation of these rats, makes this a suitable model to better understand the etiology of achalasia as well as study new management and treatment options for this incurable condition.

Magnetic resonance imaging for the study of ovarian follicles in the mouse.

Additional tools to analyze follicle development would be highly advantageous because current methods require sacrifice of animals at specific times and time-consuming sectioning of tissues for histologic analysis. Magnetic resonance imaging (MRI) may provide a less involved, faster and more cost-effective method to analyze follicles in whole ovaries. Fixed ovaries were collected at different stages of the estrus cycle and after stimulation with gonadotrophins (24 and 48 h post pregnant mares serum (PMSG), and 10 and 24 h post human chorionic gonadotrophin (hCG)) with or without administration of the contrast agent gadodiamide. The MR images were generated using a vertical-bore, 11.7 Tesla MR system. Analysis of the MR images revealed large antral follicles in fixed ovaries with the oocyte and cumulus mass identifiable within preovulatory follicles. The use of gadodiamide had no impact on the quality of MR images obtained. The fixed ovaries were paraffin embedded, sectioned, and hematoxylin stained. Follicles were counted using the MR images and the histology sections. Preovulatory follicle numbers determined using MR images were comparable to those using histology; however counts of smaller follicles were inconsistent. MRI of gonadotrophin-stimulated ovaries in situ did not reveal discernable ovarian structures. Therefore, MRI is a useful tool for studying whole fixed ovaries leaving the ovary intact for additional analyses or for selection of samples based on morphology. The MRI is also useful for identifying preovulatory follicles, although analysis of smaller follicles is not possible, and thus the potential exists for cyst analysis in mouse models of polycystic ovarian syndrome (PCOS).

Isoproterenol induces in vivo functional and metabolic abnormalities: similar to those found in the infarcted rat heart.

Chronic isoproterenol administration produces a rapid, highly reproducible rodent model of cardiac hypertrophy. Yet, despite widespread use of this model, the effects of isoproterenol on in vivo cardiac function and substrate metabolism are unknown. Isoproterenol (5 mg.kg(-1).day(-1)) was infused for 7 days in male Wistar rats (n = 22). In vivo magnetic resonance imaging (MRI) showed that left ventricular mass increased by 37% and end-diastolic and systolic volumes increased by 33% and 73%, respectively, following isoproterenol infusion. Cardiac function at the base of the left ventricle was normal, but apical ejection fraction decreased from 90% to 31% and apical free wall thickening decreased by 94%, accompanied by increased fibrosis and inflammation. Myocardial palmitate oxidation rates were 25% lower, and citrate synthase and medium chain acyl-coenzyme A dehydrogenase activities were reduced by 25% and 29%, respectively, following isoproterenol infusion. Fatty acid transporter protein levels were 11-52% lower and triglyceride concentrations were 55% lower in isoproterenol-infused rat hearts. Basal glycolysis and glycogen concentration were not changed, yet insulin stimulated glycolysis was decreased by 32%, accompanied by 33% lower insulin stimulated glucose transporter, GLUT4, protein levels in rat hearts following isoproterenol infusion, compared with controls. In conclusion, isoproterenol infusion impaired in vivo cardiac function, induced hypertrophy, and decreased both fatty acid and glucose metabolism, changes similar in direction and magnitude to those found in the rat heart following moderate severity myocardial infarction.

µ(2)-Iodido-bis-{dimeth-yl[methyl-bis(quinolin-8-yl)silanyl-κN,Si,N']platinum(IV)} tetra-kis(penta-fluoro-phen-yl)borate dichloro-methane 0.66-solvate.

The title complex, [Pt(2)(CH(3))(4)(C(19)H(15)N(2)Si)(2)I][B(C(6)F(5))(4)]·0.66CH(2)Cl(2), resulted from an attempt to synthesize a stable five-coordinate platinum species via ligand abstraction of a six-coordinate platinum precursor. However, dimerization occurred after ligand abstraction, thereby yielding the compound described in this study. The cation is a dinuclear Pt(IV) organometallic complex, in which the metal centers are bridged by an I(-) anion. Both metal centers display a coordination geometry close to octa-hedral, including cis-arranged quinoline ligands connected by Si atoms, which form Pt-Si bonds, two cis-methyl groups, and the bridging I(-) anion. In the crystal structure, voids between cations and anions are partially filled with an average of 0.66 mol-ecules of dichloro-methane solvent.

Evidence-based diabetes screening during pregnancy.

The concept of gestational diabetes was described more than a half century ago and has been studied extensively for more than 30 years. Available data indicate that the prevalence is highly variable, probably reflecting underlying risk factors. In addition, gestational diabetes is not a specific disease, but rather an abnormal laboratory value. Criteria for diagnosis are variable, and there is little agreement about who should be screened, if screening should be selective or universal, or how screening should be performed. Moreover, the most commonly used criteria in the United States differ from the European and World Health Organization standard criteria. This article describes the background for diabetes testing, current evidence for testing and diagnosis in pregnant women, "risks" of diagnosis, and various screening procedures and protocols, using data-based evidence when available. Midwifery practice recommendations are also made, including examination of risk factors as clinical decisions are made about guidelines.

Using student-collected practice data as a teaching tool.

Research is an intimidating prospect for many students. This brief and fairly simple foray into data collection and analysis did not convince all students to embrace research. It did, however, entice many to consider how to incorporate data collection into their own beginning practices. Students who had stated their aversion to research found themselves arguing for the necessity of data collection to provide evidence for practice changes. There were also students who found the experience yet another busywork paper trail invented by the faculty. They resented the time and effort required for completion of another form during their busy clinical experiences. Other students remained adamantly opposed to considering any changes in what they saw as "appropriate" practice despite evidence to the contrary. An ongoing goal of education is to facilitate lifelong learning and investigation into clinical questions. The faculty plan to survey the graduates to ascertain what data collection efforts, if any, they are currently using. The educational program described in this project closed in December 1998 because of funding restrictions. One of the faculty in this project (Carr) and current colleagues are continuing to use the NMCDS to encourage students to examine and analyze their own practices. An additional use of the data set is for student-initiated research projects that focus on specific clinical questions. One faculty member was part of an effort to institute a similar project in a master's-based nurse-midwifery education program. That database has currently provided data for two master's degree projects. The uses of the NMCDS are not limited to graduate students or advanced practice clinicians. The tool is being used in an undergraduate maternity nursing clinical course to assist students in seeing differences in practice and the possible reasons for those differences. The Division of Research of the ACNM has sponsored the development of similar data collection tools for both ambulatory prenatal and well-woman care. The wellwoman tool is currently in the pilot stage (1999), and will be refined and further tested this year. The use of these data collection tools by advanced practice nurses would provide a wealth of data for both policy setting and clinical research. Educational programs frequently combine coursework for various advanced practice nursing pathways, and nurse-midwifery and nurse practitioner students would benefit from jointly focusing on practice patterns and participating in the analysis of student-collected data. The standardized tools for intrapartum, well-woman care, and antepartum care will be available to all of the 50 ACNM education programs as well as to practicing clinicians.

Charges for maternity services: associations with provider type and payer source in a university teaching hospital.

OBJECTIVES: Considerable evidence exists that payer status influences the type and cost of services provided. If payer status influences care, consumers may receive differential care secondary to presence and type of payer. This study examines the effect of payer status on certified nurse-midwives (CNMs) and obstetricians (OBs), correcting for methodologic problems that have been noted in previous studies. METHODS/FINDINGS: Participants were 715 low-risk pregnant women seen in the CNM or OB practice in a university hospital service. All billed charges from the initial prenatal visit through two months postpartum were compared by payer. Charges by provider were also examined to determine the presence of differential payer effect. Unexpectedly, charges by payer did not show significant variance, nor did payer differently affect providers. Charges by provider type varied significantly, with CNMs having lower mean charges than OBs. CONCLUSIONS: Differences in practice by payer source were not found for either provider group. This may reflect a lack of financial incentives to alter practice based on the payer, the homogeneity of the participants, or the large number of payers. The findings indicate that provider decision-making styles are likely due to non-payer factors in a system that lacks clear incentives to alter care patterns.

Transfer of 4'-chloro-2,2':6',2"-terpyridine platinum(II) between human serum albumin, glutathione and other thiolate ligands. A possible selective natural transport mechanism for the delivery of platinum(II) drugs to tumour cells.

The antitrypanosomal and antitumour activities of (2,2':6',2"-terpyridine)platinum(II) complexes have been postulated to be due to their ability to inhibit irreversibly the NADPH/FAD redox enzymes trypanothione reductase and human thioredoxin reductase respectively. Here we show that these platinum(II) complexes metallate recombinant human albumin (rHA) at the single free thiol group (Cys-34). Moreover, the (2,2':6',2"-terpyridine)platinum(II) complex can be transferred from rHA to other thiols, such as 2-hydroxyethanethiol or glutathione. Human serum albumin could therefore provide a natural transport mechanism for the selective delivery of these agents to tumor cells by the enhanced permeability and retention (EPR) mechanism.

Evaluation of the effectiveness of a directly observed therapy program with Vietnamese tuberculosis patients.

Tuberculosis (TB) has long been recognized as major public health problem. The rate of TB is high in immigrants, and the frequency of drug resistance is increasing. A major reason for the development of resistant infections as well as relapse is poor adherence to TB treatment. In response to thi problem, directly observed therapy (DOT) was introduced to thi TB program in Santa Clara county in 1993. The purpose of thi study is to compare the completion rates, relapse rates, and sputum conversion rates between a DOT group and a non-DOT group of Vietnamese TB patients. A chart review was completed with a convenience sample of 25 records of DOT patients ani 25 records of non-DOT patients. Frequencies and percentage were used to analyze the completion rates and the relapse rates The results show that the completion of therapy rate was 16% higher in the DOT group and the relapse rate was 8% lower. A t-test indicated that the sputum conversion rate was significantly more rapid in the DOT group than in the non-DOT group (p< 0.05). Vietnamese TB patients appear to benefit from the DOT program.

The hippocampal formation participates in novel picture encoding: evidence from functional magnetic resonance imaging.

Considerable evidence exists to support the hypothesis that the hippocampus and related medial temporal lobe structures are crucial for the encoding and storage of information in long-term memory. Few human imaging studies, however, have successfully shown signal intensity changes in these areas during encoding or retrieval. Using functional magnetic resonance imaging (fMRI), we studied normal human subjects while they performed a novel picture encoding task. High-speed echo-planar imaging techniques evaluated fMRI signal changes throughout the brain. During the encoding of novel pictures, statistically significant increases in fMRI signal were observed bilaterally in the posterior hippocampal formation and parahippocampal gyrus and in the lingual and fusiform gyri. To our knowledge, this experiment is the first fMRI study to show robust signal changes in the human hippocampal region. It also provides evidence that the encoding of novel, complex pictures depends upon an interaction between ventral cortical regions, specialized for object vision, and the hippocampal formation and parahippocampal gyrus, specialized for long-term memory.

Brain choline-containing compounds are elevated in HIV-positive patients before the onset of AIDS dementia complex: A proton magnetic resonance spectroscopic study.

The CNS is frequently involved in human immunodeficiency virus (HIV) infection. In recent studies using proton magnetic resonance spectroscopy, investigators found a significant reduction in N-acetyl aspartate, a metabolic marker of neurons, in late stages of dementia. To further understand the relationship between proton magnetic resonance spectroscopy changes and clinical disease and dementia, we compared 20 HIV-infected patients presenting at varying stages of acquired immunodeficiency syndrome (AIDS) dementia complex and infection to 10 age-matched controls. We found a significant reduction in N-acetyl aspartate/creatine only in patients who had advanced dementia and CD4 counts less that 200/microliter. By contrast, a significant elevation in compounds containing choline was present in patients in the early stages of HIV infection of who had CD4 counts greater than 200/microliter, in patients with normal MRI scans, and in all AIDS dementia complex groups, including subjects with no or minimal cognitive impairment. An elevated choline level also occurred in later stages of HIV infection (CD4 < 200/microliter). Our results suggest that an increase in choline occurs before N-acetyl aspartate decrements, MRI abnormalities, and the onset of dementia, and may therefore provide a useful marker for early detection of brain injury associated with HIV infection.

Quantitative in vivo 1H nuclear magnetic resonance spectroscopic imaging of neuronal loss in rat brain.

The aim of this research was to determine whether in vivo nuclear magnetic resonance spectroscopic measurement of N-acetyl aspartate, a neuron specific brain marker, provides a quantitative index of neuronal loss. Five rats were injected unilaterally in the corpus striatum with kainic acid, an analogue of glutamate that causes excitotoxic degeneration of intrinsic neurons, and were subjected to nuclear magnetic resonance imaging and spectroscopic imaging. Measurements of N-acetyl aspartate were determined in vivo and compared to post mortem nuclear magnetic resonance spectroscopic measures of N-acetyl aspartate and choline acetyl transferase and glutamate decarboxylase activities, biochemical markers for striatal intrinsic neuronal integrity. Mean per cent neuronal survival of hemispheres with lesion versus the contralateral hemispheres measured 72 for glutamate decarboxylase and 71 for N-acetyl aspartate (in vivo), 74 for N-acetyl aspartate (in vitro), and 62 for choline acetyl transferase, respectively. Our studies in rats have shown that estimates of neuronal loss through nuclear magnetic resonance spectroscopic measurements of N-acetyl aspartate are equivalent to traditional neuronal enzyme activity assays. The results unequivocally demonstrate that N-acetyl aspartate is a valid and sensitive neuronal marker with the capability of providing accurate assessments of neuronal loss in vivo.

Functional MR in the evaluation of dementia: correlation of abnormal dynamic cerebral blood volume measurements with changes in cerebral metabolism on positron emission tomography with fludeoxyglucose F 18.

PURPOSE: To determine whether magnetic susceptibility functional MR imaging of cerebral blood volumes provides information similar to fludeoxyglucose F 18 positron emission tomography (PET) brain images in patients undergoing evaluation for dementia. METHODS: Ten subjects were studied with both PET and functional MR. Clinical diagnoses included probable Alzheimer disease (n = 5), possible Alzheimer disease (n = 1), Pick disease (n = 2), and primary progressive aphasia (n = 2). The studies were quantitatively evaluated by coregistration of PET and functional MR images followed by regression analyses of corresponding regions of interest. Qualitatively, each brain was categorized into eight regions, and each was classified as normal or abnormal by visual inspection. RESULTS: Correlation coefficients between registered functional MR and PET images were excellent (mean, r = 0.58) in most of the cerebrum. Significant correlations were observed in 72 of 74 brain sections. Qualitatively, 16 brain regions were judged to be abnormal by both MR imaging and PET; 46 regions were normal by both; 10 regions were abnormal by PET only; and 8 regions were abnormal only by functional MR. The concordance between functional MR and PET was 78%, which was highly significant. CONCLUSION: Cerebral blood volumes images derived from magnetic susceptibility (functional MR) provide information similar to fludeoxyglucose F 18 PET images in demented patients undergoing evaluation for dementia.