Gene expression of GLUT4 in skeletal muscle from insulin-resistant patients with obesity, IGT, GDM, and NIDDM.

In obesity, impaired glucose tolerance (IGT), non-insulin-dependent diabetes mellitus (NIDDM), and gestational diabetes mellitus (GDM), defects in glucose transport system activity, contribute to insulin resistance in target tissues. In adipocytes from obese and NIDDM patients, we found that pretranslational suppression of the insulin-responsive GLUT4 glucose transporter isoform is a major cause of cellular insulin resistance; however, whether this process is operative in skeletal muscle is not clear. To address this issue, we performed percutaneous biopsies of the vastus lateralis in lean and obese control subjects and in obese patients with IGT and NIDDM and open biopsies of the rectus abdominis at cesarian section in lean and obese gravidas and gravidas with GDM. GLUT4 was measured in total postnuclear membrane fractions from both muscles by immunoblot analyses. The maximally insulin-stimulated rate of in vivo glucose disposal, assessed with euglycemic glucose clamps, decreased 26% in obesity and 74% in NIDDM, reflecting diminished glucose uptake by muscle. However, in vastus lateralis, relative amounts of GLUT4 per milligram membrane protein were similar (NS) among lean (1.0 +/- 0.2) and obese (1.5 +/- 0.3) subjects and patients with IGT (1.4 +/- 0.2) and NIDDM (1.2 +/- 0.2). GLUT4 content was also unchanged when levels were normalized per wet weight, per total protein, and per DNA as an index of cell number. Levels of GLUT4 mRNA were similarly not affected by obesity, IGT, or NIDDM whether normalized per RNA or for the amount of an unrelated constitutive mRNA species. Because muscle fibers (types I and II) exhibit different capacities for insulin-mediated glucose uptake, we tested whether a change in fiber composition could cause insulin resistance without altering overall levels of GLUT4. However, we found that quantities of fiber-specific isoenzymes (phopholamban and types I and II Ca(2+)-ATPase) were similar in all subject groups. In rectus abdominis, GLUT4 content was similar in the lean, obese, and GDM gravidas whether normalized per milligram membrane protein (relative levels were 1.0 +/- 0.2, 1.3 +/- 0.1, and 1.0 +/- 0.2, respectively) or per wet weight, total protein, and DNA. We conclude that in human disease states characterized by insulin resistance, i.e., obesity, IGT, NIDDM, and GDM, GLUT4 gene expression is normal in vastus lateralis or rectus abdominis. To the extent that these muscles are representative of total muscle mass, insulin resistance in skeletal muscle may involve impaired GLUT4 function or translocation and not transporter depletion as observed in adipose tissue.

Multiple defects in the adipocyte glucose transport system cause cellular insulin resistance in gestational diabetes. Heterogeneity in the number and a novel abnormality in subcellular localization of GLUT4 glucose transporters.

Mechanisms causing cellular insulin resistance in gestational diabetes mellitus are not known. We, therefore, studied isolated omental adipocytes obtained during elective cesarean sections in nondiabetic (control) and GDM gravidas. Cellular insulin resistance was attributed to impaired stimulation of glucose transport; compared with control subjects, basal and maximally insulin-stimulated transport rates (per surface area) were reduced 38 and 60% in GDM patients, respectively. To determine underlying mechanisms, we assessed the number, subcellular distribution, and translocation of GLUT4, the predominant insulin-responsive glucose transporter isoform. The cellular content of GLUT4 was decreased by 44% in GDM patients as assessed by immunoblot analysis of total postnuclear membranes. However, GDM patients segregated into two subgroups; half expected profound (76%) cellular depletion of GLUT4 and half had GLUT4 levels in the normal range. Cellular GLUT4 was negatively correlated with adipocyte size in the control subjects and GDM patients with normal GLUT4 (r = 0.60), but fell way below this continuum in GDM patients with low GLUT4, indicating that heterogeneity was not caused by differences in obesity. All GDM. distribution. In basal cells, increased amounts of GLUT4 were detected in membranes fractionating with (such that the plasma membrane GLUT4 level in GDM (such that the plasma membrane GLUT4 level in GDM patients was equal to that observed in insulin-stimulated cells from control subjects). Furthermore, insulin stimulation induced translocation of GLUT4 from low-density microsomes to plasma membranes in control subjects but did not alter subcellular distribution in GDM patients. In other experiments, cellular content of GLUT1 was normal in GDM patients, and GLUT1 did not undergo insulin-mediated recruitment to plasma membranes in either control subjects or GDM patients. A faint signal was detected for GLUT3 only in low-density microsomes and only with one of two different antibodies. In GDM, we conclude that insulin resistance in adipocytes involves impaired stimulation of glucose transport and arises from a heterogeneity of defects intrinsic to the glucose transport effector system. GLUT4 content in adipocytes is profoundly depleted in approximately 50% of GDM patients, whereas all patients are found to exhibit a novel abnormality in GLUT4 subcellular distribution. This latter defect is characterized by accumulation of GLUT4 in membranes cofractionating with plasma membranes and high-density microsomes in basal cells and absence of translocation in response to insulin. The data suggest that abnormalities in cellular traffic or targeting relegate GLUT4 to a membrane compartment from which insulin cannot recruit transporters to the cell surface and have important implications regarding skeletal muscle insulin resistance in GDM and NIDDM.

Pregnancy following renal transplantation in a patient with insulin-dependent diabetes mellitus.

Renal transplantation and peritoneal or hemodialysis are therapeutic options increasingly available to diabetic patients with uremia. We report a patient with insulin-dependent diabetes mellitus (IDDM) and advanced retinopathy and nephropathy who had three pregnancies. Her first pregnancy resulted in a living female with Pierre-Robin syndrome and arthrogryposis. The second pregnancy, 8 mo post-kidney transplantation, necessitated a therapeutic abortion for an anencephalic fetus. Her third pregnancy, 22 mo after kidney transplantation, was associated with intensive diabetes management and resulted in delivery by cesarean section of a healthy boy. Renal and retinal function remained stable during both her second and third pregnancies. As more patients with IDDM achieve fertility post-renal transplantation, aggressive principles of diabetes regulation need to be expanded to include consideration of the interaction of the post-kidney-transplant state and diabetes mellitus during pregnancy.

Gestational diabetes: should it be added to the syndrome of insulin resistance?

OBJECTIVE: The significance of gestational diabetes mellitus (GDM) results from its short-term detrimental effects on the fetus and its long-term prediction of NIDDM in the mother. We compared several variables associated with insulin resistance between GDM and non-GDM pregnant women to show the similarities between GDM and NIDDM (and thus insulin resistance). RESEARCH DESIGN AND METHODS: On the basis of a 3-h oral glucose tolerance test (OGTT), 52 GDM patients and 127 non-GDM patients were recruited from pregnant, non-diabetic women who had a nonfasting 1-h-50-g glucose screening test > or = 7.2 mmol/l (130 mg/dl) performed between 16 and 33 weeks of gestation (a total of 518 of 3,041 women drawn from six community health care prenatal clinics were screened positive). During the OGTT, several potential markers of insulin resistance were measured at fasting and 2-h time points, in addition to the standard glucose measurements. The relationship of these variables with the diagnosis of GDM was studied. RESULTS: GDM patients, compared with non-GDM patients, had 1) higher prepregnancy weight (P = 0.011), prepregnancy BMI (P = 0.006), C-peptide at fasting (P = 0.002) and at 2 h (P < 0.001), insulin at fasting (P = 0.001) and at 2 h (P < 0.001), triglycerides at fasting (P = 0.005) and at 2 h (P = 0.003), free fatty acids at fasting (P = 0.017), beta-hydroxybutyrate at fasting (P = 0.007); and 2) lower HDL cholesterol at fasting (P = 0.029). These variables were all predictive of GDM (P < 0.036) individually. Using stepwise logistic regression with all of these variables available, fasting (P = 0.019) and 2-h (P < 0.001) insulin levels, fasting free fatty acids (P = 0.031), and fasting beta-hydroxybutyrate (P = 0.036) were statistically significant as jointly predictive of GDM. Comparisons between GDM patients and non-GDM patients matched by BMI confirmed that the metabolic abnormalities persisted when difference in BMI was taken into account. Concomitant blood pressure measurements in women with GDM did not differ significantly from those without GDM. CONCLUSIONS: Our results show that many of the known metabolic components of the syndrome of insulin resistance (syndrome X) are predictive of GDM. These results are in keeping with the argument that GDM is one phase of the syndrome of insulin resistance. We suggest that GDM be looked upon as a component of the syndrome of insulin resistance that provides an excellent model for the study and prevention of NIDDM in a relatively young age-group.

Care of diabetic pregnant women by primary-care physicians. Reported strategies for managing pregestational and gestational diabetes.

OBJECTIVE: To ascertain the strategies used by primary-care physicians for treating pregestational and gestational diabetes mellitus (GDM) during pregnancy, because many women with pregnancies complicated by these types of diabetes are treated by physicians who have no special training in intensive diabetes management. RESEARCH DESIGN AND METHODS: Two hundred twenty-four family-practice (FP) physicians and 184 obstetrics/gynecology (OB/GYN) physicians were surveyed by mail. RESULTS: When compared with OB/GYNs, FPs were less likely to screen all pregnant women for GDM (P = 0.03), use multiple-injection insulin regimens (P = 0.004) or self-monitoring of blood glucose (SMBG) (P = 0.01) for Pre-GDM patients, and refer these patients to a specialist for medical (P = 0.01) or ophthalmologic (P less than 0.001) care. FPs were more likely to implement insulin therapy (P = 0.003), SMBG (P = 0.02), and examine eyes for retinopathy (P less than 0.001) when treating gestational patients. CONCLUSIONS: These data show that there are considerable discrepancies between the strategies used by FPs and OB/GYNs and also suggest that physicians in both groups are under-utilizing recommended treatment strategies described in publications targeted specifically to primary-care physicians. Increased exposure to and dissemination of guidelines for diabetes management and additional medical school and postgraduate education programs are recommended as methods to improve utilization of these strategies.

Glucose and amino acid turnover in untreated gestational diabetes.

OBJECTIVE: Although gestational diabetes affects as many as 3% of all pregnant women, specific aspects of glucose and protein metabolism in this population have not been clearly delineated. We tested the hypothesis that gestational diabetes mellitus (GDM) results in increased glucose production and proteolysis during fasting. RESEARCH DESIGN AND METHODS: Using tracer isotope infusions, the rate of appearance (Ra) of glucose, leucine, phenylalanine and tyrosine, phenylalanine hydroxylation, leucine oxidation, and urea nitrogen excretion were determined after an overnight fast in 10 GDM subjects, within 2 weeks of diagnosis and before initiation of treatment, and in a matched control group of nine healthy nondiabetic pregnant women. RESULTS: Fasting glucose Ra was similar in GDM patients and control subjects (GDM, 12.8 +/- 1.1 vs. control subjects, 12.8 +/- 0.9 mumol . kg-1 . min-1). Leucine and phenylalanine Ra (reflecting proteolysis) also were not different between GDM patients and control subjects (GDM leucine Ra, 128 +/- 14 vs. control subjects, 124 +/- 5; phenylalanine Ra GDM, 35 +/- 4 vs. control subjects, 40 +/- 2 mumol . kg-1 . h-1). Furthermore, leucine oxidation and phenylalanine hydroxylation were not increased in GDM subjects, urea nitrogen excretion was actually lower in GDM patients. However, fasting insulin concentrations were significantly elevated in GDM subjects (GDM, 165 +/- 35 vs. control subjects, 30 +/- 5 pmol/l; P < 0.01). CONCLUSIONS: Hepatic glucose release and whole-body proteolysis in GDM patients were remarkably similar to matched pregnant control subjects. This was achieved with insulin concentrations three- to fivefold higher than normal, suggesting significant insulin resistance for both glucose and protein metabolism in GDM.

Secretion of nizatidine into human breast milk after single and multiple doses.

Disposition of the H2-receptor antagonist nizatidine was studied in serum, urine, and breast milk. Five lactating women and five nonlactating women participated; the disposition of nizatidine was studied in three of the lactating women. Single and multiple doses of 150 mg nizatidine were administered orally. The disposition of nizatidine (half-life, 1 1/2 hours; apparent serum clearance, 40 L/hr; renal clearance, 27 L/hr; and apparent volume of distribution, 1.4 L/kg) was similar in lactating and nonlactating women. These pharmacokinetic results were analogous to observations for men in other studies. Nizatidine breast milk concentrations were directly proportional to corresponding serum concentrations. On average, 96 micrograms nizatidine, less than 0.1% of the maternal dose, was secreted into milk during a 12-hour interval after either single or multiple doses.

Enhancement of binding of the dihydropyridine calcium antagonist PN200-110 to human myometrial sarcolemma by the heterologous calcium antagonist diltiazem.

Binding of the dihydropyridine calcium antagonist PN200-110 was studied in human myometrial membranes. PN200-110 bound reversibly and with high affinity to membrane fragments. The highest concentration of binding sites was found in the sarcolemma. The benzothiazepine calcium antagonist diltiazem stimulated PN200-110 binding by increasing the amount bound at equilibrium. Kinetic studies detected a fast and slow rate of dissociation in the presence of diltiazem.

Bone dysplasias: the prenatal diagnostic challenge.

The prenatal diagnosis of bone dysplasias presents difficult challenges for the clinician involved in monitoring pregnancies. Such diagnoses highlight delicate ethical issues and may require difficult decision-making when the differential diagnosis includes a lethal bone dysplasia. Despite the rapid technological advances in ultrasonography, the ability to make prenatal diagnoses within this group of disorders is limited by the restricted ultrasonographic capability to appreciate fully the detailed fetal anatomy. However, we perceive that a significant further limitation involves the lack of a systematic protocol to guide the clinician in the ultrasonographic evaluation of a fetus suspected of having a skeletal dysplasia. In an attempt to aid the clinician who is evaluating these suspected pregnancies, we report here 8 cases and propose a model protocol for the ultrasonographic diagnostic approach to fetal skeletal problems in utero.

Image acquisition context: procedure description attributes for clinically relevant indexing and selective retrieval of biomedical images.

OBJECTIVE: To support clinically relevant indexing of biomedical images and image-related information based on the attributes of image acquisition procedures and the judgments (observations) expressed by observers in the process of image interpretation. DESIGN: The authors introduce the notion of "image acquisition context," the set of attributes that describe image acquisition procedures, and present a standards-based strategy for utilizing the attributes of image acquisition context as indexing and retrieval keys for digital image libraries. METHODS: The authors' indexing strategy is based on an interdependent message/terminology architecture that combines the Digital Imaging and Communication in Medicine (DICOM) standard, the SNOMED (Systematized Nomenclature of Human and Veterinary Medicine) vocabulary, and the SNOMED DICOM microglossary. The SNOMED DICOM microglossary provides context-dependent mapping of terminology to DICOM data elements. RESULTS: The capability of embedding standard coded descriptors in DICOM image headers and image-interpretation reports improves the potential for selective retrieval of image-related information. This favorably affects information management in digital libraries.

Cutaneous mastocytosis complicating pregnancy.

BACKGROUND: Telangiectasia macularis eruptiva perstans, a rare form of cutaneous mastocytosis associated with elevated histamine excretion, has not previously been reported to complicate pregnancy. CASE: A woman presented in the late second trimester with an anaphylactoid reaction, rash, uterine contractions, and vaginal bleeding. Skin biopsy revealed perivascular mast-cell infiltration. Her urinary histamine excretion was markedly elevated. She was treated successfully with tocolytics and antihistamines. CONCLUSION: Elevated histamine excretion in biopsy-proven cutaneous mastocytosis may be associated with preterm labor.

Prenatal ultrasound detection of isolated neural tube defects: is cytogenetic evaluation warranted?

OBJECTIVE: To determine the value of cytogenetic evaluation in fetuses with isolated neural tube defects diagnosed by prenatal ultrasound. METHODS: Fifty-five thousand two hundred sixty obstetric ultrasounds performed for various indications at the Indiana University Prenatal Diagnostic Center from July 1988 to March 1994 were reviewed using a computerized data base. Excluding all cases of anencephaly, fetuses with isolated neural tube defects were identified. Maternal demographic data, pregnancy outcomes, level of defect, and fetal karyotype when available were obtained. Statistical analysis was performed using the chi 2 test, when appropriate. P < or = .05 was considered statistically significant. RESULTS: Seventy-seven medical record charts of women with prenatally diagnosed isolated fetal neural tube defects were reviewed. Nineteen pregnancies were terminated, 42 pregnancies were delivered, and 16 pregnancies were lost to follow-up. Karyotypes were available in 43 of the 77 cases (55.8%). The theoretical risk of chromosomal anomalies in this sample population based solely on maternal age was 0.3%. Of the 43 documented karyotypes, seven chromosomal anomalies were discovered (16.3%). The difference was statistically significant (P = .012). Detected chromosomal anomalies included two trisomy 18, two triploid 69,XXX, one triploid 69,XXY, one balanced Robertsonian translocation t(13q,14q), and one inversion in the q arm of the X chromosome. CONCLUSION: The prevalence of karyotypic abnormalities is significantly increased in fetuses with isolated neural tube defects; therefore, prompt antenatal genetic evaluation should be considered in such cases.

Pregnancy associated with lupus anticoagulant and heparin induced thrombocytopenia: management with a low molecular weight heparinoid.

The management of pregnant patients with coagulopathies and heparin induced thrombocytopenia is difficult and poorly defined. We report the case of a patient who was treated with a low molecular weight heparinoid. The treatment was complicated by the delayed occurrence of thrombocytopenia and a thrombotic event. This is the first report of thrombocytopenia caused by heparinoid. It is possible that this complication could have been avoided by a shorter duration of treatment with heparinoid and the use of Vitamin K antagonists during the second trimester of pregnancy.

Insulin-like growth factors I and II peptide and messenger RNA levels in macrosomic infants of diabetic pregnancies.

OBJECTIVE: Fetal macrosomia is a common complication of maternal diabetes mellitus and is associated with substantial morbidity, but the precise cellular and molecular mechanisms that induce fetal macrosomia are not well understood. We hypothesized that the macrosomia or accelerated fetal growth seen in infants of diabetic mothers is due to a perturbation of a putative placental-fetal growth axis involving growth hormone and insulin-like growth factors. Insulin-like growth factors I and II (IGF-I and IGF-II) are ubiquitous peptides that share structural homology with insulin and have been implicated in processes that control fetal growth. Studies of IGF levels in pregnancies complicated by diabetes and macrosomia have shown conflicting results. We set out to resolve these inconsistencies using molecular techniques to measure the placental IGF-I and IGF-II messenger RNA levels in placentas and a specific radioimmunoassay to measure IGF-I and IGF-II peptide levels in cord serum of normal and diabetic pregnancies. METHODS: Placentas and cord blood were collected immediately after delivery at term from patients from each of three study groups: 1) nonmacrosomic infants of nondiabetic mothers (controls), 2) macrosomic infants of diabetic mothers, and 3) nonmacrosomic infants of diabetic mothers. Both IGF-I and IGF-II levels were measured in cord serum and placental tissue by a specific radioimmunoassay. Total RNA was extracted and analyzed by Northern gels hybridized to IGF-I or IGF-II riboprobes. RESULTS: Levels of IGF-I in cord serum from the macrosomic diabetic group (83 +/- 4.2 ng/mL) were significantly higher than levels from either the nonmacrosomic nondiabetic group (38 +/- 1.9 ng/mL) or the nonmacrosomic diabetic group (13 +/- 3.5 ng/mL). There was a direct linear correlation between cord serum IGF-I and infant birth weight, independent of diabetes (r2 = 0.61, P < .01). On the other hand, IGF-II cord serum levels were elevated in diabetic pregnancies (337 +/- 12.2 ng/mL) compared with nondiabetic women (172 +/- 19.8 ng/mL), but there was no correlation with birth weight (r2 = 0.035, P = .52). In contrast to cord blood levels, IGF-II peptide levels were significantly decreased in the placentas from mothers with diabetes compared with nondiabetic controls (116 +/- 3.2 versus 158 +/- 5.3 ng/mL, respectively). Levels of IGF-I peptide in placentas from both nondiabetic controls and diabetic mothers were below the sensitivity of the assay. Levels of IGF-I and IGF-II mRNA did not differ in placentas from diabetic mothers versus nondiabetic controls. CONCLUSION: Cord serum IGF-II levels are elevated in diabetic pregnancies without a concomitant increase in placental IGF-II levels. This novel finding, combined with the finding that IGF-I levels are correlated with macrosomia independent of the diabetic state, contributes to our understanding of the possible mechanisms involved in fetal growth in pregnancies complicated by diabetes.

Gestational diabetes mellitus and gene mutations which affect insulin secretion.

We investigated whether genetic mutations known to impair insulin secretion and glucose tolerance are operative in a group of American women with gestational diabetes mellitus. Study groups were comprised of elderly non-diabetic controls (n = 55) with normal glucose tolerance and patients with gestational diabetes (n = 50), together with one family with maturity-onset diabetes of the young (three controls and three affected). No mutations were detected in any exon of the human glucokinase gene or the mitochondrial tRNA[Leu](UUR) gene by single strand conformational analysis and direct exon sequencing. Also, chi2 analysis showed no significant association with gestational diabetes for a polymorphism at position -30 (G --> A) of the beta-cell-specific glucokinase gene promoter. We have determined that glucokinase and mitochondrial tRNA[Leu](UUR) gene mutations, which are known to impair insulin secretion are relatively uncommon and do not constitute a large component of genetic risk for gestational diabetes in the study population.

Is a third-trimester antibody screen in Rh+ women necessary?

OBJECTIVE: To determine the need for routine third-trimester antibody screening in Rh+ women. STUDY DESIGN: An analytic case-control study. METHODS: We identified Rh+ pregnant women who had received prenatal care and retrospectively analyzed their laboratory data. Patients were grouped into those with a positive third-trimester antibody screen (cases) and those with a negative third-trimester screen (controls). Because entry into a group was decided by the investigators, it could not be randomized. We reviewed the maternal medical records for antibody identification and final pregnancy outcome. We also reviewed the neonatal medical records for evidence of direct Coombs-positive cord blood, anemia, need for transfusion or phototherapy, other medical complications, and death. RESULTS: Using a computerized laboratory database from 2 teaching hospitals, we identified 10,581 obstetric patients who underwent routine first- and third-trimester antibody screening between 1988 and 1997. Of these, 1233 patients were Rh- and 9348 were Rh+. Among the Rh+ patients, 178 (1.9%) had 1 or more atypical antibodies at the first-trimester screen, and 53 (0.6%) had a positive third-trimester antibody screen despite a negative first-trimester screen. Although 6 of these 53 patients (0.06% of the study population) had clinically relevant antibodies for hemolytic disease of the new-born, no significant neonatal sequelae occurred among these 6 patients. CONCLUSION: Based on the patient and hospital records studied, a repeat third-trimester antibody screen for Rh+ patients is clinically and economically unjustified. Eliminating this laboratory test from clinical practice will not adversely affect pregnancy outcomes and will decrease the costs of prenatal care.

The association of aneuploidy and unexplained elevated maternal serum alpha-fetoprotein.

OBJECTIVE: The purpose of this study was to examine fetal chromosomal abnormalities in pregnancies complicated by unexplained elevated maternal serum alpha-fetoprotein (MSAFP). STUDY DESIGN: We reviewed, using a computerized database, 58,162 obstetrical ultrasounds that were performed for various indications. Fetuses with MSAFP multiples of the median (MOM) > or = 2.5 and normal extensive ultrasounds were identified. Maternal demographic data and fetal karyotype were obtained. RESULTS: Seven hundred eighty-nine patients received ultrasounds for evaluation of elevated MSAFP. Of the 595 patients with normal scans, 195 (32.8%) underwent amniocentesis and cytogenetic evaluation. Two chromosomal abnormalities were detected (1.0%), including an inversion and a balanced translocation. CONCLUSION: The two karyotypic abnormalities identified in our study consisted of structural rearrangements. Patients undergoing karyotype analysis for unexplained elevated MSAFP should be counseled that the types of aneuploidy detected under this circumstance differ from those associated with advanced age and specific fetal anomalies (trisomy and triploidy).

Pharmacologic cardioversion of intrauterine supraventricular tachycardia. A case report.

Fetal supraventricular tachycardia was converted successfully with digoxin, and the congestive heart failure resolved. Previous case reports of fetal supraventricular tachycardia have established guidelines for its treatment; digoxin remains the drug of choice.