Transformation and tumorigenic properties of a mutant polyomavirus containing a middle T antigen defective in Shc binding

Polyomavirus middle T antigen is phosphorylated on several tyrosine residues which act as binding sites for cellular proteins, including phosphatidylinositol 3-kinase, Shc, and phospholipase C-gamma. In this report we describe the transforming properties and tumor-inducing ability of a polyomavirus that contains a single-site mutation in middle T antigen which changes a tyrosine residue at amino acid position 250 to serine. This mutation disrupts the association of middle T with the transforming protein Shc. The mutant virus is weakly transforming, inducing foci which are smaller and of different morphology than those of the wild type. Although the virus induced tumors in close to 100% of inoculated mice, the spectrum of tumors and their morphology were altered compared to those of wild-type virus. The mutant virus induced a reduced frequency of kidney and thymic tumors. Both the mammary gland and the thymic tumors that were induced were histologically distinct from those induced by wild-type polyomavirus. These results demonstrate that the signal transduction pathway that is deregulated by the middle T-Shc association is important for full transformation of cells in culture and for tumor induction in some target tissues in the mouse-polyomavirus system.

Solving the mystery of the Colorado Brown Stain

The life and work of Dr. Frederick S. McKay in solving the mystery of the Colorado Brown Stain changed the objectives of restorative and preventive dentistry. McKay was an intellectually diversified man whose personal interests ranged from economics to opera. Professionally his strong commitment to research led to dedicate thirty years of his life to the search for the mysterious agent that caused the Colorado Brown Stain which mottled but also produced caries-free teeth. His discovery of fluoride in drinking water and its effect on enamel was a critical breakthrough in understanding the etiology and prevention of dental caries. This discovery is the foundation for water fluoridation which is the single most effective public health measure to inhibit tooth decay.

Effects of pramlintide, an analog of human amylin, on plasma glucose profiles in patients with IDDM: results of a multicenter trial

The effects of subcutaneous administration of 10, 30, or 100 microg q.i.d. pramlintide, an analog of human amylin, on plasma glucose regulation in patients with IDDM were evaluated in a multicenter trial. The plasma glucose response to a Sustacal test meal was significantly reduced compared with placebo both after 1 week and after 2 weeks of administration of 30 or 100 microg pramlintide. In addition, 24-h mean plasma glucose concentrations were significantly lowered in patients receiving 30 microg of pramlintide for 2 weeks compared with placebo, while the 100-microg pramlintide dose did not reach statistical significance for the 24-h glucose profiles. At 10 microg, pramlintide had no effect on the 24-h glucose profile or on the plasma glucose response to a Sustacal test meal. The reduction in 24-h glucose concentrations and glucose concentrations after the Sustacal test meal observed at the 30-microg pramlintide dose was not accompanied by an increased incidence of hypoglycemic events. The most frequent adverse events were dose-related and involved transient upper gastrointestinal symptoms. A majority (>80%) of the patients who reported these adverse events during week 1 did not report them in week 2. These data indicate that pramlintide effectively reduces plasma glucose concentrations as reflected in both a 24-h glucose profile and a Sustacal test meal while maintaining an acceptable safety profile.

Resolution of CNS lesions following treatment of experimental allergic encephalomyelitis in macaques with monoclonal antibody to the CD18 leukocyte integrin

Experimental allergic encephalomyelitis (EAE) in macaques is an acute inflammatory and demyelinating disease of the central nervous system (CNS) which has been studied extensively as a model of the human demyelinating disease multiple sclerosis (MS). The in vivo administration of monoclonal antibodies against CD18, the common beta-chain of a leukocyte integrin, at the onset of clinical disease, significantly prolonged the survival of nine of 11 macaques (82%) and in some cases completely reversed the clinical appearance of disease. Treatment with anti-CD18 mAbs dramatically reduced the extent of inflammation in brain lesions as determined by magnetic resonance imaging (MRI). These improvements confirm that anti-CD18 mAbs are powerful anti-inflammatory agents in vivo and suggest that such mAbs may provide effective treatment of both demyelinating and inflammatory CNS diseases in man.

Portal venous thrombosis in a backpacker: the role of exercise

Effort thrombosis usually afflicts an extremity and is caused by compression. This case report, in contrast, involves superior mesenteric and left portal vein septic thrombosis in a backpacker following prolonged hiking and abdominal straining. The condition may have been caused by localized splanchnic venous ischemia, erosion of the bowel-blood barrier, and release of bacterial endotoxin in this dehydrated and detrained athlete. Diagnosis of this disorder is aided by noting characteristic abdominal pain, fever, nausea, and vomiting, as well as by imaging with MRI, CT, or duplex ultrasonography. Antibiotics and anticoagulants are key to treatment.

Lifespan and lesions in genetically heterogeneous (four-way cross) mice: a new model for aging research

Genetically heterogeneous animal models provide many advantages for research on aging but have been used infrequently. We present here lifespan and lesion data from a study of mice bred as a cross between (AKR/J x DBA/2J)F1 females and (C57BL/6J x SJL/J)F1 males. In such a four-way cross population, each mouse is genetically unique, but replicate populations of essentially similar genetic structure can be generated quickly, at low cost, and of arbitrary size from commercially available, genetically stable hybrid parents. We employed a protocol in which mice judged to be severely ill were euthanatized to obtain tissue in optimal condition for necropsy, and we were able to infer a likely cause of illness in 42 of 44 animals. Malignant lymphoma, including at least four histopathologically distinct subtypes, was the most common cause and was also a frequent incidental finding in mice dying of other causes. Neoplastic disease, benign or malignant, was the sole or a contributing cause of illness in 90% of the mice for which a cause could plausibly be assigned. A wide range of lethal and nonlethal degenerative lesions was also noted. The coefficient of variation for lifespan in these genetically heterogeneous mice was 26%, similar to that seen in analyses of recombinant inbred mouse lines. Baseline lifespan and pathology data on four-way cross mice is a useful prelude to the exploitation of this rodent model in tests of genetic and mechanistic hypotheses about aging.

Continuous quality improvement can improve glycemic control for HMO patients with diabetes

OBJECTIVE

To evaluate the impact of a continuous quality improvement (CQI) intervention on glycemic control of patients with diabetes mellitus attending a primary care clinic.

METHODS

A CQI process designed by the Minnesota Department of Health to improve diabetes care was implemented at a volunteer clinic, with another similar clinic not using the CQI process assessed for comparison. Adults with diabetes were identified at both clinics using diagnostic and pharmacy databases. Glycosylated hemoglobin (HbA1c) values (reference range, 4.3%-6.1%) and out-patient utilization and charges were compared for all patients with diabetes at each clinic for the 12 months before and 18 months after initiation of the CQI intervention.

RESULTS

The mean HbA1c value at the intervention clinic fell from 8.9% at baseline to 8.4% at 12 months and to 7.9% at 18 months. The mean HbA1c value at the comparison clinic was 8.9% at baseline, 8.9% at 12 months, and 8.8% at 18 months (difference between clinics, t = 4.13, P < .001). Differences after the intervention in the proportion of patients at the comparison clinic (n = 121) vs the intervention clinic (n = 122) with HbA1c values of 8% or less (40% vs 51%), between 8% and 10% (33% vs 37%), and 10% or greater (27% vs 12%) were unlikely due to chance (chi 2 = 9.7, 2 df, P = .008). The intervention was not associated with increased utilization of outpatient visits or outpatient charges.

CONCLUSIONS

Involvement of nurses, physicians, and managers in a CQI process can improve patients' glycemic control in some health maintenance organization primary care settings, without increasing utilization or charges. Health maintenance organizations should consider CQI as one possible method to improve diabetes outcomes.

Empirical techniques for determining the reliability, magnitude, and pattern of neuropsychological change after epilepsy surgery

PURPOSE

We assessed test-retest neuropsychological performance in patients with complex partial seizures to derive reliable change indices (RCIs) and regression-based norms for change, indices that may be helpful in assessing cognitive outcome after anterior temporal lobectomy.

METHODS

Forty patients with complex partial seizures (CPS) who did not undergo epilepsy surgery were administered a comprehensive neuropsychological battery on two occasions. Their test-retest data were used to compute both RCIs and regression-based norms for change for each neuropsychological index. RCIs corrected for practice effects provide a confidence interval (CI) indicating the degree of performance change required to exceed the variability attributable to sources of error (e.g., practice, test-retest reliability). Regression-based norms for change also correct for several sources of measurement error and examine observed versus expected test-retest changes on a common metric, thereby facilitating determination of the degree and relative magnitude of change across cognitive domains.

RESULTS

Mean changes in test-retest performance were generally modest, but were evident across several test measures. Our data indicate a considerable degree of individual variability in test-retest performance.

CONCLUSIONS

RCIs and regression-based norms are complementary indexes and can be particularly useful in examining the test-retest performance of individual patients who undergo epilepsy surgery as well as in the more general investigation of cognitive outcome after epilepsy surgery.

Safety of commercial air travel following myocardial infarction

BACKGROUND

Travelers occasionally suffer myocardial infarction (MI) while abroad. Existing guidelines recommend a 4- to 24-week convalescent period following MI before air travel should be permitted.

HYPOTHESIS

Air travel may be undertaken safely in the early post-MI period.

METHODS

The aeromedical transport records of two international medical assistance companies over a 3-yr period were reviewed. We identified 209 patients who suffered MI; 13 transported by private air ambulance were excluded. We reviewed the aeromedical transports of the remaining 196 adults carried on commercial aircraft between 3-53 d post-MI to investigate the safety of air travel in this group. Data were recorded regarding patient age; sex; location of MI; complications of MI; presence of medical escort; duration of flight(s); use of oxygen, medications, or cardiac monitoring during transport; and development of symptoms in flight.

RESULTS

Within 7 d of their acute MI 3 patients (2%) were transported; 87 (44%) between days 8-14 post-MI; 65 (33%) between days 15-21; 27 (14%) between days 22-28; and 14 (7%) more than 28 d post-MI. Some 187 patients (95%) were transported without incident; 9 (5%) patients experienced symptoms requiring evaluation by the escorting physician. Of the 9, 6 problems occurred in patients being transported less than 14 d post-MI. Symptoms resolved spontaneously or immediately after physician intervention in all but one case.

CONCLUSION

International aeromedical transport of patients may be safely accomplished 2-3 wk after an acute MI when an accompanying physician is present. Recommendations for delaying travel more than 4 wk after infarction are not supported by clinical experience and should be revised.

A carbon monoxide irreducible form of cytochrome c oxidase and other unusual properties of the "monomeric" shark enzyme

Contrary to previous reports, the functional and spectral properties of "monomeric" shark cytochrome c oxidases are not entirely similar to those of the "dimeric" beef enzyme. Most significantly, unlike the behavior of beef oxidase, the fully oxidized shark enzyme is not reducible by carbon monoxide. Also, preparations of the shark enzyme, isolated at pH 7.8-8.0, lead to more than 60% of the sample always being obtained in a resting form, whereas similarly prepared beef oxidase is very often obtained, both by ourselves and others, exclusively in the pulsed form. Although the electronic absorption, magnetic circular dichroism and electron paramagnetic resonance (EPR) spectra of cytochrome c oxidase obtained from several shark species are similar to those of the beef enzyme, there are some significant differences. In particular, the Soret maximum is at 422 nm in the case of the fully oxidized resting shark oxidases at physiological pH and not 418 nm as commonly found for the beef enzyme. Moreover, the resting shark oxidases do not necessarily exhibit a "g = 12" signal in their EPR spectra. The turnover numbers of recent preparations of the shark enzyme are higher than previously reported and, interestingly, do not differ within experimental uncertainty from those documented for several beef isoenzymes assayed under comparable conditions.

Human disodium octaborate tetrahydrate exposure following carpet flea treatment is not associated with significant dermal absorption

Disodium octaborate tetrahydrate is used for indoor flea control on carpets and furniture. Disodium octaborate tetrahydrate was applied to a 100% nylon carpet as a solution using a powered rug brush at a rate of approximately 200 micrograms/cm2 carpet. Two randomly chosen groups of volunteers (18 females, 4 males) wore either bathing suits which provided 75% or more skin exposure or whole-body, cotton dosimeters consisting of socks, union suits, and gloves. The volunteers performed a 20-minute set of Jazzercise routines. The availability of boron was demonstrated by covering portions of the carpet with a cotton dosimeter and rolling it with a weighted roller. Additionally, disodium octaborate tetrahydrate was transferred to the whole-body dosimeter. Volunteers also collected 24-hour urine specimens prior to and following the exercise period. The specimens were analyzed for total boron by inductively coupled plasma emission spectroscopy. No evidence of contact transfer and dermal absorption was obtained. The mean daily boron levels (mg/g creatinine) were 1.17, 1.33, and 1.31 for the group with exposed skin and 1.26, 1.12, and 1.26 for those who wore dosimeters which prevented contact. Daily urine boron levels were not significantly different when compared using a two sample t-test assuming equal variances (P > 0.05). Direct dermal contact with disodium octaborate tetrahydrate-treated carpet at a nominal rate of 200 micrograms/cm2 did not produce any adverse effects or change urinary boron clearance.

An 'other-race effect' for categorizing faces by sex

It is well-known that people recognize faces of their own race more accurately than faces of other races-a phenomenon often referred to as the 'other-race effect'. Using brief presentations of faces, we show a similar effect for the task of discriminating the sex of a face. Specifically, Caucasian observers discriminated male and female Caucasian faces more accurately/efficiently than did Oriental observers, and Oriental observers discriminated male and female Japanese faces more accurately/efficiently than did Caucasian observers. This result indicates that, under suboptimal viewing conditions, the identification of even the most salient of facial characteristics-face sex-is impaired for other-race faces. This finding suggests, also, that the nature and diversity of our experience with faces may affect not only the quality of the face representation for later access by recognition processes, but also the efficiency of a perceptual discrimination process. Intriguingly, too, we found that female observers, for both races tested, were considerably more accurate at the sex classification task than were male observers.

Ventricular pacing threshold and refractoriness after defibrillation shocks in patients with implantable cardioverter-defibrillators

The aim of this study was to examine the effect of ventricular fibrillation and a subsequent defibrillation shock on ventricular excitability and refractoriness in human beings. We studied 16 consecutive patients with implantable cardioverter-defibrillators undergoing follow-up studies. The pre- and post-shock pacing threshold, ventricular effective refractory period, monophasic action potential duration, and serum catecholamine levels were measured. Compared with the baseline state, immediately after ventricular fibrillation, and a successful defibrillation shock: (1) the ventricular effective refractory period decreased from 251 +/- 24 ms to 222 +/- 30 ms (p < 0.01), (2) the monophasic action potential duration decreased from 210 +/- 16 ms to 179 +/- 23 ms (P < 0.01) at 50% repolarization and from 274 +/- 24 ms to 240 +/- 26 ms (P< 0.01) at 90% repolarization, (3) the pacing threshold was not significantly altered and, (4) serum levels of epinephrine and norepinephrine were elevated. These results show that although ventricular fibrillation and subsequent defibrillation had no effect on the ventricular pacing threshold in human beings, it was associated with a decrease in post-shock monophasic action potential duration and ventricular effective refractory period, contrary to some previously reported findings.

Overexpression of 2',3'-cyclic nucleotide 3'-phosphodiesterase in transgenic mice alters oligodendrocyte development and produces aberrant myelination

The function of the intracellular protein 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) of oligodendrocytes (ODC) is unknown. We have now generated several homozygous transgenic mouse lines in which the human CNP gene is overexpressed up to sixfold, revealing new insights into early stages of myelinogenesis. Although no behavioral phenotype is immediately apparent, abnormalities of ODC and their myelin sheaths are striking. These are manifested as redundant myelin membrane and intramyelinic vacuoles, as well as lack of myelin compaction concordant with failure of the cytoplasmic leaflets of compact myelin to fuse. Further, ODC that overexpress CNP appear to mature earlier in development, resulting in earlier maximum gene expression for myelin basic proteins and proteolipid protein. These results indicate that CNP is an early expressed regulator of cellular events that culminate in CNS myelination.

Effect of 14 days' subcutaneous administration of the human amylin analogue, pramlintide (AC137), on an intravenous insulin challenge and response to a standard liquid meal in patients with IDDM

Individuals with insulin-dependent diabetes mellitus (IDDM or type 1 diabetes) are deficient in both insulin and amylin, peptides secreted by the beta cell. We have investigated the effects of amylin replacement therapy employing the human amylin analogue, pramlintide (25, 28, 29-pro-human amylin, previously referred to as AC137), upon the responses to a standardized insulin infusion (40 mU. kg-1. h-1) for 100 min and a liquid Sustacal meal (360 kcal) in 84 healthy IDDM patients. Following baseline evaluations, patients were randomly assigned to receive subcutaneous injections of placebo, 30, 100 or 300 micrograms pramlintide 30 min before meals for 14 days. There was no meaningful difference between adverse events reported by the 30-micrograms pramlintide and the placebo groups, but ten subjects withdrew due to nausea, eight of these in the 300-micrograms dose group. Peak plasma pramlintide concentrations for the 30-micrograms group were 21 +/- 3 and 29 +/- 5 pmol/l on Days 1 and 14, respectively. These values are similar to postprandial plasma amylin concentrations in normal volunteers. The plasma glucose, free insulin, glucagon, epinephrine and norepinephrine concentrations during the insulin infusion test before and after therapy were identical in each of the group. Prior to pramlintide therapy, Sustacal ingestion produced a 4.0-4.8 mmol/l rise in plasma glucose concentrations in each of the groups. Pramlintide therapy reduced postprandial hyperglycaemia as reflected by the 3-h incremental AUCglucose (AUCglucose above or below fasting glucose concentration) Day 1 vs Day 14: 30 micrograms, 322 +/- 92 vs -38 +/- 161 mmol/l.min, p = 0.010; 100 micrograms, 317 +/- 92 vs -39 +/- 76 mmol/l.min, p = 0.001; and 300 micrograms, 268 +/- 96 vs -245 +/- 189 mmol/l.min, p = 0.077. Thus, pramlintide therapy with these regimens did not appear to impair either in vivo insulin action or the counter-regulatory response to hypoglycaemia but did show a clear effect of blunting postprandial hyperglycaemia following a standardized meal.

High reproducibility in the interpretation of intraoperative transesophageal echocardiographic evaluation of aortic atheromatous disease

Intraoperative decisions are often based on interpretation of results from transesophageal echocardiography (TEE). One such area is the intraoperative evaluation of atheromatous disease of the thoracic aorta and subsequent classification or grading. These grading schemes are predictive of stroke after cardiac surgery. Since intraoperative strategies may be modified based on this TEE aortic atheroma grading, assessment of the interobserver variability of TEE findings between observers is essential. Forty TEE videotape segments imaging three portions of the thoracic aorta (ascending, arch, descending) were selected from 189 reports of a larger cohort. Three independent, blinded observers, experienced in TEE, evaluated these examinations for atheroma severity. If a TEE segment had insufficient data, "uninterpretable" was recorded. Weighted kappa coefficients of agreement were calculated on the three data sets. Mean weighted kappa coefficients for the three observers A, B, and C were 0.69, 0.74, and 0.72, for the ascending, arch, and descending aorta segments, respectively, representing excellent agreement. We have demonstrated uniformly high agreement for interpretation of TEE, which indicates the excellent reproducibility of TEE grading and stratification of aortic atheroma. Reproducibility within and across specialties and institutions is essential for widespread application of TEE for evaluation of the thoracic aorta.

Interactions between the ankyrin repeat-containing protein Akr1p and the pheromone response pathway in Saccharomyces cerevisiae

Akr1p, which contains six ankyrin repeats, was identified during a screen for mutations that displayed synthetic lethality with a mutant allele of the bud emergence gene BEM1. Cells from which AKR1 had been deleted were alive but misshapen at 30 degrees C and inviable at 37 degrees C. During a screen for mutants that required one or more copies of wild-type AKR1 for survival at 30 degrees C, we isolated mutations in GPA1, which encodes the G alpha subunit of the pheromone receptor-coupled G protein. (The active subunit of this G protein is G beta gamma, and G alpha plays an inhibitory role in G beta gamma-mediated signal transduction.) AKR1 could serve as a multicopy suppressor of the lethality caused by either loss of GPA1 or overexpression of STE4, which encodes the G beta subunit of this G protein, suggesting that pheromone signaling is inhibited by overexpression of Akr1p. Mutations in AKR1 displayed synthetic lethality with a weak allele of GPA1 and led to increased expression of the pheromone-inducible gene FUS1, suggesting that Akr1p normally (and not just when overexpressed) inhibits signaling. In contrast, deletion of BEM1 resulted in decreased expression of FUS1, suggesting that Bem1p normally facilitates pheromone signaling. During a screen for proteins that displayed two-hybrid interactions with Akr1p, we identified Ste4p, raising the possibility that an interaction between Akr1p and Ste4p contributes to proper regulation of the pheromone response pathway.

Monomeric ferric heme peptide derivatives: model systems for hemoproteins

Electron paramagnetic resonance spectra of a number of ferric heme peptide derivatives, in aqueous-detergent and various aqueous-alcohol solvent mixtures, have been obtained using samples in the concentration range 0.1-1.0 mM. Some of these were clearly monomeric, homogeneous, mixed-ligand adducts, entirely suitable for use as model systems for hemoprotein spectroscopic studies. As anticipated, the measured EPR parameters were largely independent of solvent environment. Surprisingly, micellar preparations of ferric heme undecapeptide in mildly alkaline solution showed no evidence for the formation of a hydroxide adduct, contrary to a previous report [S. Mazumdar, O. K. Medhi and S. Mitra, Inorg. Chem. 30 700 (1991)].

Determination of ventricular vulnerable period and ventricular fibrillation threshold by use of T-wave shocks in patients undergoing implantation of cardioverter/defibrillators

BACKGROUND

This study was designed to characterize the ventricular vulnerable period (VVP) and ventricular fibrillation (VF) threshold by use of T-wave shocks in patients undergoing implantation of cardioverter/defibrillators. A premature condensed shock applied during the VVP can induce VF. Most studies on the VVP and VF threshold have been conducted in animals rather than in humans.

METHODS AND RESULTS

Twenty-one patients undergoing implantation of Medtronic PCD Jewel 7219D cardioverter/defibrillators because of ventricular tachycardia and/or VF were enrolled. All had structural heart disease. Their ages ranged from 42 to 85 years (mean, 69 +/- 11.3 years). Seventeen (80.9%) had atherosclerotic coronary artery disease. The right ventricle (RV) was driven at a cycle length (S1) of 400 ms, and monophasic shocks (S2) of 0.6 J were delivered through an RV apex lead (cathode) and a superior vena cava lead (anode) during the T wave of each cardiac cycle. The longest and shortest S1-S2 intervals that were capable of inducing sustained VF were defined as the outer and inner limits of the VVP at an energy level of 0.6 J, respectively. To determine the VF threshold, a shock of 0.2 J was applied at the midpoint of the VVP at 0.2-J increments until sustained VF was induced. The lowest energy setting capable of inducing sustained VF was defined as the VF threshold. Of the 21 patients, the VVP at an energy level of 0.6 J averaged 53.8 +/- 26.0 ms. Characteristically, the VVP started from the ascending limb of the T wave and ended at or slightly beyond the peak of the T wave, occupying 12.2 +/- 5.8% of the QT interval. The midpoint of the VVP used for determination of the VF threshold measured 0 to 90 ms (mean, 32.9 +/- 26.0 ms) before the peak of the T wave. Of the 21 patients, 16 (76.2%) had a VF threshold at < or = 0.2 J (estimated 57 V), 3 at 0.4 J (estimated 81 V), and 2 at 0.6 J (estimated 99 V).

CONCLUSIONS

The VF threshold is low (< or = 0.2 J) in the majority of patients requiring implantation of cardioverter/defibrillators. Further studies are needed to define clinical usefulness of the study technique relative to its potential role for risk stratification and for assessing antifibrillatory properties of antiarrhythmic drugs in this subset group of patients.

The site of the redox-linked proton pump in eukaryotic cytochrome c oxidases

The electronic spectra of fully oxidized derivatives of some cytochrome c oxidase preparations are distinctly pH dependent. In general, the observed spectral shifts are greater in the case of pulsed derivatives compared to resting preparations and also, greater for preparations of the enzyme from shark skeletal muscle compared to beef heart. The low temperature near-infrared magnetic circular dichroism spectrum of the fully oxidized shark enzyme is not pH dependent in the experimental range, indicating the sensitivity of the visible region electronic spectrum to variation in pH to be due principally to changes at the heme a3-CuB chromophore. The results are discussed in relation to proposed mechanisms of proton translocation in cytochrome c oxidase.