Impaired glucose tolerance and increased weight gain in transgenic rats overexpressing a non-insulin-responsive phosphoenolpyruvate carboxykinase gene

The effects of an overexpressed, non-insulin-responsive gluconeogenic enzyme, phosphoenolpyruvate carboxykinase (GTP) (PEPCK; EC 4.1.1.32), on glucose homeostasis were investigated. Transgenic rats harboring a metallothionein-driven PEPCK gene (lacking the entire PEPCK upstream-regulatory region) expressed transgene PEPCK mRNA in the key gluconeogenic tissues, liver and kidney. Female transgenic rats, studied at 10 weeks of age, showed mild fasting hyperglycemia (6.9 +/- 0.2 vs. 5.9 +/- 0.1 mM P = 0.002 n = 6), hyperinsulinemia (92.2 +/- 4.0 vs. 54.0 +/- 6.6 pM, P = 0.001, n = 6), impaired glucose tolerance and increased weight gain (178.3 +/- 3.2 vs. 153.4 +/- 2.5 g, P = 0.001, n = 16 and n = 13 transgenic and control rats, respectively). Despite hyperinsulinemia at this age, kidneys of transgenic rats maintained a significant 20% elevation of total PEPCK enzyme activity, while total liver PEPCK activity was not reduced. This study suggests that an insulin-resistant step in the gluconeogenic pathway can lead to glucose intolerance and an increase in weight. These rats offer the unique opportunity to study the metabolic consequences of chronic, mild excess glucose supply, as seen in non-insulin-dependent diabetes.

Carotid steal syndrome: a case study

The progression of subclavian arterial stenosis and the subsequent formation of collateral pathways serve to alter the pressure gradients in subclavian steal syndrome, altering ipsilateral vertebral artery flow from its normal state to "latent," "transient," and "continuous" steals. A similar altered flow in the carotid arteries can be observed with stenosis of the proximal common or innominate artery. A 59-year-old man was seen in the vascular laboratory for evaluation of symptomatic peripheral arterial disease. An incidental asymptomatic stenosis of the right innominate and left proximal subclavian artery was found. Further cerebral vascular evaluation displayed a continuous right subclavian steal and a latent steal in the right internal carotid artery. Transcranial Doppler examination displayed "transient" steal in the terminal right internal carotid artery. Combining duplex and transcranial Doppler evaluations allows sequential evaluation of the progression of arterial disease and its effect on the flow patterns in the cerebral vasculature.

Human fructose-1,6-bisphosphatase gene (FBP1): exon-intron organization, localization to chromosome bands 9q22.2-q22.3, and mutation screening in subjects with fructose-1,6-bisphosphatase deficiency

Fructose-1,6-bisphosphatase (EC 3.1.3.11) is a key regulatory enzyme of gluconeogenesis that catalyzes the hydrolysis of fructose-1,6-bisphosphate to generate fructose-6-phosphate and inorganic phosphate. Deficiency of fructose-1,6-bisphosphatase is associated with fasting hypoglycemia and metabolic acidosis because of impaired gluconeogenesis. We have cloned and characterized the human liver fructose-1,6-bisphosphatase gene (FBP1). FBP1, localized to chromosome bands 9q22.2-q22.3 by fluorescence in situ hybridization, consists of seven exons that span > 31 kb, and the six introns are in the same position as in the rat gene. FBP1 was screened for mutations in two subjects with fructose-1,6-bisphosphatase deficiency. Four nucleotide substitutions were identified, two of which were silent mutations in the codons for Ala-216 (GCT-->GCC) and Gly-319 (GGG-->GGA). The other substitutions were in intron 3, a C-->T substitution 7 nucleotides downstream from the splice donor site, and in the promoter region, an A-->T substitution 188 nucleotides upstream from the start of transcription. These nucleotide substitutions were also found in normal unaffected subjects and thus are not the cause of fructose-1,6-bisphosphatase deficiency in the two subjects studied. The molecular basis of hepatic fructose-1,6-bisphosphatase deficiency in these subjects remains undetermined but could result from unidentified mutations in the promoter that decrease expression or from mutations in another gene that indirectly lead to decreased fructose-1,6-bisphosphatase activity.

Diabetes-like renal glomerular disease in Fanconi-Bickel syndrome

The Fanconi-Bickel syndrome is a rare inherited disorder of metabolism characterized by hepatic glyconeogenesis, galactose intolerance, renal Fanconi syndrome with nephromegaly, and glycogen accumulation in proximal renal tubular cells. An 8-year-old patient with this disease and severe rickets due to medically resistant hypophosphatemia was found to have the previously unrecognized complication of renal glomerular hyperfiltration, microalbuminuria, and diffuse glomerular mesangial expansion. Similar to patients with glucose-6-phosphatase deficiency, the glomerular disease in this patient resembles incipient diabetic nephropathy. The Fanconi syndrome may be due to the defective transport of glucose at the proximal tubular basolateral membrane, which results in accumulation of glucose and secondarily glycogen within tubular cells. Since the metabolic defect, as evidenced by glycogen accumulation, selectively involves proximal renal tubular cells in the kidney of patients with Fanconi-Bickel syndrome and glucose-6-phosphatase deficiency, the abnormalities in renal glomerular hemodynamics and mesangial construct in these rare diseases are likely due to renal tubular factors, if the mechanism originates in the kidney. A delineation of these phenomena may further our understanding of the pathogenesis of diabetic nephropathy.

"Is this man your daddy?" suggestibility in children's eyewitness identification of a family member

Studies of natural language development suggest that overextension of family memberships terms, such as daddy or papa, occurs in children in the second year of life, but rarely persists thereafter. However, in British Courts it is common for the testimony of 3- and even 4-year-olds to be dismissed on the grounds that these children may not be reliably identifying their father or stepfather when they claim that daddy was the perpetrator of abuse. This study examined whether 3-year-olds could be persuaded to confirm that a stranger who was labelled as daddy was their own father. A mock interview with experienced disclosure interviewers was conducted. Five of the 17 children--all from blue-collar families--misidentified a photograph of their own father when an identification question was repeated. Rather than undermining the validity of all preschoolers testimony, it is suggested that the responses of some children to apparently mundane questions of fact are influenced by contextual factors, including repetition of the question and the perceived omniscience of the interviewer.

Twin-twin transfusion syndrome: intraamniotic pressure measurement in the assessment of volume reduction at serial amniocenteses

Two cases of severe twin-twin transfusion syndrome are described. In both, serial amniocenteses were followed by resolution of the disordered inter-twin haemodynamics with 4 intact term survivors. In all reports to date of aggressive reduction with or without successful outcome, volume reduction has been dictated by subjective or semiquantitative ultrasonic estimates of liquor volume. With the use of intraamniotic pressure estimation we describe a more rational basis for the removal of these large volumes of amniotic fluid.

Oral physostigmine and impaired memory in adults with brain injury

The purpose of this study was to examine the effects of physostigmine, a cholinergic agonist, on memory loss after traumatic brain injury (TBI), as compared to placebo or scopolamine, a cholinergic antagonist, using a double-blind, placebo-controlled design. Each subject received each active drug and placebo. Neuropsychological measures (Wechsler Memory Scale I and II, Selective Reminding Test, Trail-Making Test, Parts A and B, Digit Symbol, and Memory Questionnaire) and measures of clinical balance were completed at baseline, after each drug phase, and at 1 month follow-up. Thirty-six subjects completed the study with results showing an improvement in memory scores in 44% of subjects (responders) while taking oral physostigmine. The most sensitive measure was the Selective Reminding Test, specifically Long-term Storage. The impact of drugs on standing balance as compared to placebo was improved standing time in the responders: (1) with physostigmine when standing tandem with eyes closed (p < 0.05), and (2) with scopolamine when standing on one foot with eyes closed (p < 0.05). Results support the potential benefit of cholinergic agonists on memory after TBI and the need for further research of possible clinical markers for the drug.

Strict metabolic control and retinal blood flow in diabetes mellitus

The effects of strict diabetic control on retinal haemodynamics were studied to elucidate whether such effects are associated with retinopathy changes. In 28 patients with poorly controlled insulin dependent diabetes mellitus and non-proliferative retinopathy, retinal haemodynamics were investigated at baseline, 5 days, 2 months, and 6 months after the institution of strict diabetic control using the bidirectional laser Doppler velocimetry technique and monochromatic fundus photography. Changes in retinal blood flow measured in a major retinal vein (Q) on the fifth day of strict diabetic control correlated significantly with changes in retinopathy level observed at the end of the 6 months of this study (rank correlation 0.65, p < 0.01). On the fifth day of strict diabetic control, 16 out of 20 eyes that showed no progression (NP) of retinopathy at the end of the study had decreases in Q, whereas six out of eight eyes that showed progression (P) had increases in Q. The difference in these changes in Q between P and NP eyes was statistically significant (one way analysis of variance, p = 0.001). No significant changes in Q were detected at 2 months or 6 months. Following the institution of strict diabetic control, no significant changes in time were detected in the regulatory response to 100% oxygen breathing characterised as the percentage decrease in Q at 4-6 minutes of oxygen breathing (analysis of variance, p = 0.36). Changes in Q following institution of strict diabetic control are associated with progression of retinopathy. Measurements described in this study may help identify diabetic patients at risk of progression when their metabolic control is improved.

Antimalarial measures--type, sources of advice and compliance among tourists to Natal/KwaZulu

Typical advice on antimalarial measures provided by pharmacies as well as actual behaviour in this regard and sources of advice accessed by tourists to northern Natal/KwaZulu were canvassed by telephonic interviews with 70 pharmacies and 53 'care providers' (members of travel parties). Doctors (26%) and pharmacists (40%) were the most commonly approached sources of antimalarial advice. Professional recommendations frequently involved chloroquine-based drugs (80% of recommended drugs), despite the chloroquine-resistant status of the study area. Drug choice reflected the limited availability of new alternatives to chloroquine at the time the study was conducted, as well as ignorance of drug resistance in the area. Possible reasons for the inappropriate nature of many of the reported recommendations, as well as an approach to the dissemination of future prophylactic policy documents, are discussed.

Spouse similarity in attitudes, personality, and psychological well-being

The study of the origin of spouse similarity is interesting because the extent to which spouse similarity reflects genetic resemblance between husbands and wives affects the genetic structure of a population. The sources of observed spouse similarity in attitudes, personality, and psychological well-being are discussed. Analyses based on data collected from an American adult sample assessed longitudinally showed that spouse correlations were high for attitudes and low to moderate for personality and psychological well-being. Four competing explanations to spouse similarity were compared: initial similarity, attrition, convergence, and age covariation. The results did not support the latter three explanations, indicating that initial similarity may be an appropriate interpretation of observed spouse similarity. The findings are consistent with those of other comparable studies.

Glycogen storage disease in adults

OBJECTIVE

To identify complications amenable to prevention in adults with glycogen storage disease (GSD) types Ia, Ib, and III and to determine the effect of the disease on social factors.

DESIGN

Case series and clinical review.

SETTING

Referral medical centers in the United States and Canada.

PATIENTS

All patients with GSD-Ia (37 patients), GSD-Ib (5 patients), and GSD-III (9 patients) who were 18 years of age or older.

MEASUREMENTS

Ultrasound or radiographic studies identified liver adenomas, nephrocalcinosis, or kidney stones. Radiographic studies identified osteopenia. Reports of the clinical examination, serum chemistry results, and social data were obtained.

RESULTS

For patients with GSD-Ia, problems included short stature (90%), hepatomegaly (100%), hepatic adenomas (75%), anemia (81%), proteinuria or microalbuminuria (67%), kidney calcifications (65%), osteopenia or fractures or both (27%), increased alkaline phosphatase (61%) and gamma-glutamyltransferase (93%) activities, and increased serum cholesterol (76%) and triglyceride (100%) levels. Hyperuricemia was frequent (89%). Patients with GSD-Ib had severe recurrent bacterial infections and gingivitis. In patients with GSD-III, 67% (6 of 9) had increased creatinine kinase activity. Four of these patients had myopathy and cardiomyopathy.

CONCLUSIONS

For GSD-Ia, hyperuricemia and pyelonephritis should be treated to prevent nephrocalcinosis and additional renal damage. For GSD-Ib, granulocyte-colony-stimulating factor may prevent bacterial infections. For GSD-III, more data are required to determine whether the myopathy and cardiomyopathy can be prevented. Most of the patients with GSD-I and GSD-III had 12 or more years of education and were either currently in school or employed.

Extracellular ATP induces stellation and increases glial fibrillary acidic protein content and DNA synthesis in primary astrocyte cultures

A number of factors appear to be involved in the proliferative and hypertrophic processes which characterize reactive astrocytosis. We have investigated the possibility that ATP, an agent that is released by injured cells following tissue destruction, may be one such factor. For this purpose, we utilized primary cultures of astrocytes derived from cerebral cortices of neonatal rats to study the effect of extracellular ATP on properties associated with astrogliosis. Light microscopic studies disclosed marked stellation of astrocytes after 30-60 min of exposure to 100 microM-1 mM ATP. In addition, the content of the astrocyte-specific intermediate filament, glial fibrillary acidic protein (GFAP), was increased 35-40% following 60-min exposure to ATP; this effect persisted for 1-3 days of exposure to 100 microM ATP. [3H]Thymidine incorporation increased progressively from 1-3 days; a 3.6-fold increase in DNA synthesis was observed following 3 days of exposure to 1 mM ATP, suggesting stimulation of cellular proliferation. These findings show that high micromolar to low millimolar concentrations of extracellular ATP reproduce several features associated with reactive gliosis and suggest that extracellular ATP may be involved in the activation of astrocytes following CNS injury.

Response rates--an evolution

The documented frequency of response of cancers to common chemotherapy agents and combinations appears to have decreased over the decades. Multiple reasons exist for this decline including: changes in eligibility and evaluability criteria; changes in the type of patients entered onto trial; and, altered criteria for response and methods for response assessment. The disinclination to publish negative results also permits a bias in a favor of overestimating a drug's efficacy. Circumspection now is advised in assessing data from older trials.

In vitro and in vivo effects of granulocyte colony-stimulating factor on neutrophils in glycogen storage disease type 1B: granulocyte colony-stimulating factor therapy corrects the neutropenia and the defects in respiratory burst activity and Ca2+ mobilization

Children with glycogen storage disease (GSD) type 1b are susceptible to recurrent bacterial infections and have chronic neutropenia accompanied by phagocytic cell dysfunction including decreased superoxide anion (O2-) generation, calcium (Ca2+) mobilization, and chemotactic activity. Granulocyte colony-stimulating factor (G-CSF), a cytokine that corrects neutropenia in other diseases, in vitro enhances f-Met-Leu-Phe-triggered neutrophil O2- generation. Short-term pretreatment (15 min) of GSD 1b neutrophils with G-CSF increased the rate of O2- production (p < 0.01); however, this rate was still significantly below the rate of O2- production in control neutrophils. Recombinant human G-CSF (5 micrograms/kg/d) was administered s.c. to a GSD 1b patient. Before treatment, absolute neutrophil counts were < 500/mm3. Two d after G-CSF administration, the absolute neutrophil counts increased to 1333 and remained in the normal range during a 12-mo follow-up period. In vivo, G-CSF therapy increased f-Met-Leu-Phe-stimulated O2- production to 52% of control after 1 mo, and by mo 4, O2- production reached control levels. Our previous studies (J Clin Invest 56:196-202, 1990) demonstrated that decreased O2- production in neutrophils was associated with impaired Ca2+ mobilization. In vivo administration of G-CSF increased f-Met-Leu-Phe-triggered Ca2+ mobilization by neutrophils to 43% of control by mo 1 of G-CSF therapy and to 93% of control by mo 4, thus paralleling the improvements in O2- generation. In contrast, G-CSF therapy had no effect on the defective neutrophil chemotaxis. In summary, G-CSF therapy produced a rapid increase in circulating neutrophils and a gradual correction of O2- production.(ABSTRACT TRUNCATED AT 250 WORDS)

Randomized clinical trial of mitomycin-C with or without pretreatment with WR-2721 in patients with advanced colorectal cancer

The use of mitomycin for metastatic colorectal cancer has been limited by mitomycin's myelosuppressive potential. The objective of this randomized study was to determine whether WR-2721 would decrease the hematologic toxicity of mitomycin in patients with colorectal cancer resistant to fluorouracil-based therapy. Ninety-seven patients with refractory colorectal cancer were randomized to receive either mitomycin 20 mg/m2 only or the same dose of mitomycin after pretreatment with WR-2721, 910 mg/m2. The principal toxicity in both groups was thrombocytopenia. The platelet nadirs were lower in patients receiving single-agent mitomycin (P = 0.026). Surprisingly, no clinical complete or partial responses were noted in either group, and survival was not different between the two groups. Thus, while WR-2721 decreased the thrombocytopenia associated with mitomycin therapy, mitomycin was ineffective in the treatment of refractory colorectal carcinoma.

Characterization of the peripheral-type benzodiazepine receptors in cultured astrocytes: evidence for multiplicity

In mammalian brain peripheral benzodiazepine (PBZD) receptors are predominantly localized on astroglial cells. Previous studies utilizing whole membrane preparations from brain and peripheral organs of various species have indicated several distinctions between the drug-receptor interactions of the two prototypic PBZD receptor ligands, PK 11195 and Ro5-4864. The present study was undertaken to determine whether putative differences in the binding of PBZD receptor ligands in homogenates of primary astrocyte cultures can be interpreted as the labeling of PBZD receptor subtypes. Equilibrium competition and saturation binding experiments in homogenate preparations of primary astrocytes from cerebral cortex of new born rats revealed that [3H]PK 11195 labels twice the number of [3H]Ro5-4864 binding sites. Unlabeled Ro5-4864 competes for [3H]PK 11195 binding in a manner suggesting the existence of multiple PK 11195 binding sites. The competition binding experiments, using various benzodiazepines, indicate that one binding component of PK 11195 corresponds to Ro5-4864 binding sites, whereas the second is different. The latter binding site does not correspond to the central BZD receptor but displays the pharmacological properties of the PBZD receptor. Further differences between the binding of PK 11195 and Ro5-4864 in astrocytes were detected in the presence of ethanol which was more effective in inhibiting the binding of the latter. Subcellular distribution studies indicated, however, that the binding of both [3H]PK 11195 and [3H]Ro5-4864 is associated primarily with the mitochondrial fraction of astrocytes. Taken together, the present study indicates the existence of non-overlapping PBZD binding sites in astrocytes and thus suggests the existence of PBZD receptor subtypes.(ABSTRACT TRUNCATED AT 250 WORDS)

Short- and long-term use of octreotide in the treatment of congenital hyperinsulinism

Octreotide, a long-acting analog of somatostatin that inhibits insulin release, has the potential to control hypoglycemia in infants with congenital hyperinsulinism. To examine the efficacy and side effects of octreotide, we evaluated therapy between 1988 and 1993 in 16 infants who did not respond to diazoxide. In nine patients with onset of severe hypoglycemia in the first days of life, octreotide was helpful in stabilizing plasma glucose levels and allowed reductions in the rates of glucose infusion; however, glucose control was inadequate to avoid subtotal pancreatectomy. In two of these nine patients postoperatively and in seven other infants, a trial of long-term treatment with octreotide was undertaken. Four were treated successfully for up to 4.3 years. Octreotide therapy was not associated with thyroid deficiency and caused only transient malabsorption. All patients receiving long-term therapy had some decrease in linear growth and two had subnormal plasma concentrations of insulin-like growth factor I and insulin-like growth factor binding protein 3 compatible with suppression of growth hormone by octreotide. Resistance to octreotide therapy, even with increasing doses, occurred in all patients. These results suggest that octreotide may aid in the acute or long-term treatment of congenital hyperinsulinism in a limited number of selected cases.