Thyroid hormone and thyroid hormone analogues in the treatment of heart failure

The thyroid hormone analogue DITPA is a promising potential new treatment for heart failure. Although the mechanism of action is incompletely determined, it is clear that DITPA improves systolic as well as diastolic function. It is also clear that the effects of DITPA are intrinsic to the muscle and not the result of changes in the structure or geometry of the left ventricle. On the basis of these experimental studies, we applied to the USA Food and Drug Administration for an Investigational New Drug application to study the use of DITPA in patients. These studies are currently in progress. While we await the outcome of these clinical trials, it is important to emphasize that even if the end-point is not a new drug to treat heart failure, our investigations are based on a systematic evaluation integrating biochemistry and physiology. We believe that this is the way to approach the problem of developmental pharmacology.

[Imaging of cancer using positron emission tomography]

Positron emission tomography (PET) is a method making use of short half-life radioactive compounds which allow imaging and quantification of functional and metabolic data at the level of multiple organs. This method has been initially oriented towards neurological and cardiological applications but gets now a more widespread use in oncology. This recent development has been made possible thanks to methodological progresses allowing "whole body" imaging and thanks to the use of a practical tracer, the 2-[18 F]fluoro-2-deoxy-D-glucose (FDG). The uptake of this tracer is enhanced in diverse cancer tissues. Recent studies has clarified the biological processes which lead to this enhanced uptake of FDG in cancers. This new insight allows a rational and helpful usage of PET in diverse aspects of clinical oncology: diagnosis of lesion, staging, follow-up of patients and treatment evaluation.

Immunological reconstitution and correlation of circulating serum inflammatory mediators/cytokines with the incidence of acute graft-versus-host disease during the first 100 days following unrelated umbilical cord blood transplantation

We investigated early immunological reconstitution and the production of circulating inflammatory mediators and their relationship to aGVHD in children during the first 100 days following unrelated UCBT. Nine patients had an underlying malignant disease (ALL, ANLL), and two, non-malignant diseases (SAA, ALD). The median age was 10 years (range: 1.25-21). Seven of 11 patients were alive by day 100, two died from regimen-related toxicity, and two died from severe aGVHD (grade >/=III). Myeloid engraftment (ANC >/=500/mm3 x 2 days) occurred at a median of 24 days (range: 14-55), while platelet engraftment (platelet count >/=20 000/mm3 untransfused x 7 days) was delayed and occurred at a median of 52 days (range: 33-95). The mean cell dose of CD34+ cells was 3.3 +/- 3.51 x 10(5)/kg, and of CD34+/CD41+ cells was 3.94 +/- 3.99 x 10(4)/kg. Acute GVHD (grade II-IV) developed in seven patients (77%), and severe aGVHD (grade III-IV) developed in five patients (55%). Serum levels of IL-2Ralpha, IL-2, IL-4, IL-7, IL-12, and IFNgamma were not significantly different between patients with grades 0-I aGVHD and patients with grades II-IV aGVHD. Evaluation of immunological reconstitution on day 90 post UCBT demonstrated an early recovery of the absolute numbers of B cells (CD19+) and NK cells (CD3-/CD56+). Immunoglobulin levels for IgG, IgM and IgA remained normal throughout the study period. PMN functional studies demonstrated normal superoxide generation, bacterial killing (BK), and chemotaxis (CTX). However, both helper (CD3+/CD4+) and suppressor (CD3+/CD8+) T cell subsets remained low during the first 100 days post UCBT with mean +/- s.e.m. values of 120 +/- 29/mm3 and 10 +/- 50/mm3, respectively (normal = 900-2860/mm3 (CD3/CD4), normal = 630-1910/mm3 (CD3/CD8)). Mitogen response studies showed low blastogenesis to PHA and PWM, with a mean c.p.m. +/- s.e.m. value of 1.7 +/- 0.67 x 10(4) for PHA (NL >/= 75 x 10(3)) and 8.42 +/- 4.1 x 10(3) for PWM (NL >/=25 x 10(3)). In conclusion, serum levels of inflammatory mediators were not predictive nor did they correlate with the severity of aGVHD. Recovery of NK cells, B cells, and PMN functions occurred within the first 90 days post transplant. However, T cell subsets, CD3+/CD4+ and CD3+/CD8+, and T cell functional activity remained significantly decreased and may account for the high incidence of infectious morbidity seen during this immediate post UCBT period.

Radiation therapy for consolidation of metastatic or recurrent sarcomas in children treated with intensive chemotherapy and stem cell rescue. A feasibility study

PURPOSE

To assess the role of consolidative radiation therapy (CRT) in conjunction with myeloablative therapy with or without total body irradiation (TBI) in children and young adults with metastatic or recurrent sarcoma.

METHODS AND MATERIALS

Twenty-one pediatric sarcoma patients with metastatic (10) or recurrent (11) disease were entered on a prospective feasibility study of intensive myeloablative therapy with or without TBI. Median patient age was 17.8 years (range, 9.4-24.7 years). Primary histologies included Ewing's (12), PNET (3), and other soft tissue sarcomas (6). Twenty patients received induction chemotherapy. Myeloablative therapy consisted of TBI in 11 patients with either high dose melphalan/etoposide (9) or high dose cytoxan/thiotepa (2). TBI consisted of 12 Gy in 2 Gy fractions delivered twice daily over 3 days. Ten patients received high dose chemotherapy alone, either with thiotepa/carboplatinum/etoposide (8) or cytoxan/carboplatinum (2). Myeloablative therapy was followed by autologous stem cell rescue (ASCR) 24 to 48 hours after completing chemotherapy. Fourteen patients (67%) received CRT either prior to (5) or following (9) myeloablative therapy. Median CRT dose was 37.2 Gy (range, 20-60). Fifty-one disease sites were present prior to myeloablative therapy. Twelve (24%) were bulky (> 8 cm) and 18 (35%) underwent surgical debulking. The median follow-up of surviving patients was 15 months (range, 8-20) with 25% of patients having been followed for more than 20 months.

RESULTS

The 3-year actuarial disease-free (DFS) and overall survival (OS) rates for the entire group were 36% and 27%, respectively. Following myeloablative treatment, responses were: 11 complete, 6 partial, 1 stable, and 3 progressive disease. Sixteen patients (71%) have relapsed. The most common site of relapse was the lung (13). Of the 51 disease sites present prior to myeloablative therapy, 36 sites (71%) were amenable to CRT. Nonamenable sites were: multiple lung metastases (13) and bone marrow (2). Twenty-six amenable sites (51%) received CRT either prior to (14) or following (12) ASCR. Amenable sites treated with CRT had a better 3-year actuarial local control (80 vs 37%) (p = 0.0065) than amenable sites not treated with CRT. Factors associated with improved disease-free survival (DFS) in univariate analysis were induction chemotherapy response (p = 0.002) and extent of surgical resection (p = 0.045). There was a trend toward improved DFS on univariate analysis with the use of TBI as part of myeloablative therapy (p = 0.07). The one factor associated with improved OS on univariate analysis was induction chemotherapy response (p = 0.007). Multivariate analysis revealed that induction chemotherapy response is the only factor that remains significant for DFS (p = 0.032) as well as for OS (p = 0.017). Patients with complete response to induction therapy had 40% probability of survival versus all other patients who had 10% survival (p = 0.05).

CONCLUSION

Consolidative radiotherapy is feasible in primary metastatic or recurrent pediatric sarcoma patients treated with myeloablative therapy with or without TBI. CRT to sites amenable to irradiation provided an improved 3-year actuarial local control than that seen in sites amenable to CRT that did not undergo radiotherapy. There was a trend for improved DFS with the use of TBI. Improved DFS and OS can be predicted by response to induction therapy. This intensive regimen may improve the cure rate of advanced pediatric sarcomas in select patients.

Effects of endothelial and inducible nitric oxide synthases inhibition on circulatory function in rats after myocardial infarction

OBJECTIVES

To examine the relative roles of eNOS and iNOS (endothelial and inducible nitric oxide synthases) on basal and beta-adrenergic receptor (beta-AR)-stimulated arterial hemodynamic responses after myocardial infarction (MI).

METHODS

Left ventricular (LV) pressures and steady-state and pulsatile arterial hemodynamics were measured at baseline, and after acute NOS inhibition with either NG-nitro-L-arginine methyl ester (L-NAME, 100 mg/kg) or iNOS inhibition with aminoguanidine (AG, 75 mg/kg) in sham-operated and MI Sprague-Dawley rats.

RESULTS

In sham rats, L-NAME decreased (P < 0.05) peak positive LV dP/dt and aortic blood velocity by 19% and 53%, respectively, and increased (P < 0.05) mean arterial pressure (MAP); systemic vascular resistance, and LV end-diastolic pressure (EDP) by 20, 189 and 89%, respectively. The frequency-dependent components of hemodynamics including aortic input impedance modulus, characteristic impedance, and phase shift were increased (P < 0.05) with L-NAME, while pulsatile power was decreased (P < 0.05). AG increased (P < 0.05) aortic input impedance modulus and characteristic impedance but had no effect on any other hemodynamic variable. In MI rats, L-NAME decreased (P < 0.05) LV dP/dt and aortic blood velocity by 22 and 55%, respectively, and increased (P < 0.05) SVR by 108%. There was no effect of L-NAME on MAP or LV EDP in MI rats. After MI, AG increased (P < 0.05) heart rate and LV dP/dt but had no effect on other LV or pulsatile hemodynamic variables. Compared to sham rats, heart rate, LV dP/dt, and blood velocity-isoproterenol dose responses were shifted downward (P < 0.05), while SVR-isoproterenol dose response was shifted upward (P < 0.05) in MI rats. In sham rats, L-NAME potentiated (P < 0.05, at > 10(-2) micrograms/kg) the isoproterenol-induced increase in LV dP/dt and aortic blood velocity, and potentiated (P < 0.05) the isoproterenol-induced decline in SVR. As expected, AG had no effects on isoproterenol-stimulated hemodynamics in sham rats. After MI, there was no effect of L-NAME or AG on isoproterenol-stimulated hemodynamics.

CONCLUSIONS

(1) Circulatory and cardiac responses to inhibition of NO by L-NAME suggest that eNOS, but not iNOS, is the principal regulator of integrated arterial hemodynamic function in rats. (2) Both basal and beta-AR-stimulated NO regulation of hemodynamic are attenuated after MI. (3) The attenuation of arterial hemodynamic effects after isoproterenol is mediated, in part, by alterations in the beta-AR-activation of eNOS system after MI.

Prophylactic coronary artery revascularization for elective vascular surgery: study design. Veterans Affairs Cooperative Study Group on Coronary Artery Revascularization Prophylaxis for Elective Vascular Surgery

This article describes the design of an ongoing randomized trial intended to test whether patients who require elective vascular surgery would benefit from preoperative coronary artery revascularization prior to the vascular procedure. The primary objective is to determine whether coronary artery revascularization reduces long-term mortality (mean 3.5 years) in patients undergoing vascular surgery. The study design calls for 620 patients to be randomized and followed for a mean of 3.5 years following vascular surgery. Secondary endpoints include measures of quality of life and cost-effectiveness. Patients with coronary artery disease in need of an elective vascular operation are considered candidates for the study. Anatomic exclusion criteria include ejection fraction <20%, severe aortic stenosis (valve area <1.0 cm2), left main stenosis > or =50%, nonobstructive coronary artery disease (stenosis <70%), and coronary arteries that are not amenable to revascularization. Prior to the vascular surgery, the trial randomizes eligible patients to coronary artery revascularization (either bypass surgery or angioplasty) versus medical therapy. The trial stratifies the randomization by hospital and type of vascular surgery (intraabdominal versus infrainguinal) because of differences in long-term prognosis in those patients. A 1-year feasibility trial involving five Veterans Affairs (VA) medical centers of variable vascular surgical loads has been completed. The results showed that over 90% of expected patients could be randomized. As a result, a larger VA Cooperative Study involving 18 centers will begin recruitment of patients. The findings should help determine the best strategy for managing patients with coronary artery disease in need of elective vascular surgery.

Overexpression of endothelium nitric oxide synthase reverses the diminished vasorelaxation in the hindlimb vasculature in ischemic heart failure in vivo

After myocardial infarction (MI), nitric oxide (NO)-mediated vasorelaxation is attenuated in both conduit and resistance arteries. To determine if the attenuated vasorelaxation after MI is due to downregulation of eNOS protein, pharmacological, immunoblotting, and gene transfer of eNOS were performed in rats 3 weeks after MI. Gene transfer was accomplished using a "first-generation" serotype 5, replication-deficient, adenoviral vector (1.2 x 10(9) pfus) containing eNOS cDNA in the hindlimb vasculature for 30 min. Five days after infection, overexpression of eNOS protein was confirmed by immunohistochemical staining and immunoblotting. Recombinant gene expression was localized primarily to the vascular endothelial cells. After MI, eNOS protein level decreased (3.3 +/- 0.9 vs 2.1 +/- 0.8 intensity units/microg protein, n=6, P<0.05); after gene transfer it increased (P<0.05) two-fold to 4.3 +/- 1.2 intensity units/microg protein, n=5. There were no changes in hemodynamics in MI rats transfected with eNOS. Acetylcholine (ACh)-stimulated vasorelaxation was decreased (P<0.05) by 30% after MI and was restored to normal with eNOS transfection. Addition of 100 microm NG-nitro-L-arginine methyl ester (L-NAME) abolished the difference between sham, MI, and MI transfected rats. L-arginine (1 mm) restored the ACh-response in MI-transfected rats toward control, but it did not eliminate the difference between MI and sham rats. We conclude that the attenuated endothelial NO-mediated vasorelaxation in the hindlimb after MI is due to a downregulation of eNOS protein and overexpression of eNOS transgene restores normal endothelial NO-mediated vasorelaxation.

Pergolide potentiates L-DOPA-induced dopamine release in rat striatum after lesioning with 6-hydroxydopamine

We used intrastriatal microdialysis to study the effect of pergolide, a D1/D2 dopamine (DA) receptor agonist on biotransformation of exogenous L-DOPA in hemi-Parkinsonian rats. DA and metabolites were assayed by microbore liquid chromatography. Pergolide (50 micrograms/kg, i.p.) caused a 67% and 87% decrease in striatal EC levels of DA in intact and denervated striatum respectively. In intact striatum but not in denervated striatum, pergolide decreased EC levels of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) (53% and 42% decrease, respectively). L-DOPA (100 mg/kg, i.p.) produced significant increase in EC levels of DA, DOPAC and HVA in intact and denervated striatum with and without local perfusion of 10(-4) M pergolide. In denervated striatum, L-DOPA-induced DA increase was significantly higher in rats with pergolide. Our results suggest that, in an animal model of Parkinson's disease, pergolide in association with L-DOPA favors the restoration of striatal EC DA levels.

Mitogen-activated protein kinase in human eggs

Mitogen-activated protein (MAP) kinase in human eggs has been investigated by using immunoblotting with both anti-Active MAPK and anti-ERK2 antibodies. The results showed that the main form of MAP kinase was p42ERK2. It was in a dephosphorylated form in oocytes at the germinal vesicle stage, but fully phosphorylated in unfertilised mature eggs. MAP kinase phosphorylation was significantly decreased when pronuclei were formed after intracytoplasmic sperm injection. Neither MAP kinase expression nor activity was detected in morphologically degenerated eggs. Although MAP kinase still existed in early embryos arrested at the 8-cell or morula stages, little, if any, activity could be detected. These data suggest that MAP kinase may play an important role in the cell cycle regulation of human eggs, as in other mammalian species.

Impaired effective cortical connectivity in vegetative state: preliminary investigation using PET

Vegetative state (VS) is a condition of abolished awareness with persistence of arousal. Awareness is part of consciousness, which itself is thought to represent an emergent property of cerebral neural networks. Our hypothesis was that part of the neural correlate underlying VS is an altered connectivity, especially between the associative cortices. We assessed regional cerebral glucose metabolism (rCMRGlu) and effective cortical connectivity in four patients in VS by means of statistical parametric mapping and [18F]fluorodeoxyglucose-positron emission tomography. Our data showed a common pattern of impaired rCMRGlu in the prefrontal, premotor, and parietotemporal association areas and posterior cingulate cortex/precuneus in VS. In a next step, we demonstrated that in VS patients various prefrontal and premotor areas have in common that they are less tightly connected with the posterior cingulate cortex than in normal controls. These results provide a strong argument for an alteration of cortical connectivity in VS patients.

Effects of AT1 receptor blockade after myocardial infarct on myocardial fibrosis, stiffness, and contractility

Angiotensin II type 1 (AT1) receptor blockade attenuates myocardial fibrosis after myocardial infarction (MI). However, whether inhibition of fibrosis by AT1 receptor blockade influences myocardial stiffness and contractility is unknown. We measured left ventricular (LV) hemodynamics, papillary muscle function, and myocardial stiffness and fibrosis in rats randomized to losartan or placebo 1 day after MI and treated subsequently for 8 wk. Losartan decreased LV and right ventricular weights as well as mean aortic and LV systolic pressures in sham and MI rats. LV end-diastolic pressure increased after MI and was decreased with losartan. Maximal developed tension and peak rate of tension rise and decline were decreased in MI vs. sham rats. Interstitial fibrosis developed after MI and was prevented in losartan-treated MI rats. The development of abnormal myocardial stiffness after MI was prevented by losartan. After MI, AT1 receptor blockade prevents an abnormal increase in myocardial collagen content. This effect was associated with a normalization of passive myocardial stiffness.

Influence of baseline lipids on effectiveness of pravastatin in the CARE Trial. Cholesterol And Recurrent Events

OBJECTIVES

We sought to assess the influence of baseline lipid levels on coronary event rates and the effectiveness of pravastatin therapy in the Cholesterol And Recurrent Events (CARE) study.

BACKGROUND

The CARE study cohort provided a relatively unique opportunity to examine the relation between lipid levels and clinical events in a post-myocardial infarction (MI) population with relatively low cholesterol and low density lipoprotein (LDL) cholesterol values.

METHODS

There were 4,159 patients with a previous infarct and a total cholesterol level <240 mg/dl, LDL cholesterol level 115 to 174 mg/dl and triglyceride level <350 mg/dl randomly allocated to placebo (n=2,078) or pravastatin 40 mg/day (n=2,081). Time to either coronary death or nonfatal MI (primary end point) or to the secondary end point, which included undergoing a coronary revascularization procedure, was determined as a function of baseline lipids (total, LDL, high density lipoprotein [HDL] cholesterol and triglyceride levels).

RESULTS

Quartile analysis indicated important effects for LDL cholesterol, in which a higher LDL was associated with greater cardiac event rates (in the placebo group, every 25-mg/dl increment in LDL was associated with a 28% increased risk [5% to 56%, p=0.015]) in the primary event. The differential event rates with respect to baseline LDL cholesterol for placebo and pravastatin groups reduced the difference in clinical outcomes at lower LDL cholesterol levels. In both the placebo and pravastatin groups, an inverse relation between baseline HDL cholesterol and cardiac events was observed (10 mg/dl lower baseline HDL cholesterol level was associated with a 10% [0% to 19%, p=0.046] increase in coronary death or nonfatal MI).

CONCLUSIONS

Within the LDL cholesterol levels in CARE (115 to 174 mg/dl), baseline values influenced both the risk of events in the placebo group as well as the clinical effectiveness of pravastatin therapy.

Brain glucose metabolism in eating disorders assessed by positron emission tomography

OBJECTIVE

As anorectic and bulimic patients present similar clinical and neurobiological symptoms, the purpose of this study was to compare brain glucose metabolism at rest in these patients.

METHODS

Positron emission tomography with (18-F)-fluorodeoxyglucose was used to evaluate cerebral glucose metabolism (CMRglu) in 10 normal-weight bulimic women, in 10 underweight anorectic patients, and in 10 age- and sex-matched healthy volunteers.

RESULTS

Absolute global cortical glucose activity was significantly lower in anorectic patients compared with bulimic and control subjects. Anorectic patients compared with normal control subjects also showed higher relative CMRglu in the inferior frontal cortex and in the basal ganglia, and putamen and caudate relative hypermetabolism when compared with bulimic patients. Thus, both eating disorder groups differed from control subjects in low relative parietal values of glucose.

DISCUSSION

While absolute global metabolism seems to be related to weight loss, we can hypothesize either a common parietal cortex dysfunction in eating disorders or a particular sensitivity of this cortex to consequences of eating disturbances.

Perisylvian dysgenesis. Clinical, EEG, MRI and glucose metabolism features in 10 patients

We studied 10 patients who had neurological disorders with a MRI-based diagnosis of perisylvian dysgenesis based on the fact that the parasagittal and centrifugal extremity of the sylvian fissure was abnormally mesial. This abnormality was bilateral in seven cases; in the other three patients, the contralateral sylvian fissure appeared either normal (two cases) or enlarged (open operculum). The perisylvian cortex had a polymicrogyric appearance in most patients. Potential aetiopathogenic factors were determined in four patients. In two of them, ischaemia at mid-gestation was ascribed to death of a co-twin in a context of monozygotic twinning. In the other two patients, who were siblings, genetic factors were suspected. Pseudobulbar palsy was found in eight patients and epilepsy in five patients. We used PET with [18F]fluorodeoxyglucose to test the hypothesis that, despite this clinical and MRI heterogeneity, regional cerebral glucose distribution could have common features in these patients. The analysis of PET data was performed by visual inspection in two cases and by using statistical parametric mapping (SPM) in eight patients compared with a control group. Segmented grey matter MRIs of seven out these patients were also analysed using SPM. We found that the abnormal perisylvian cortex had normal grey matter activity in eight patients and in the other two there was a heterogeneous pattern with areas of preserved metabolism and of decreased metabolism. Metabolic changes were also detected outside the polymicrogyric-like cortex; three patients had hypometabolic areas in cortical regions where the MRI appeared normal and had a normal intensity. When polymicrogyria extended into the white matter, this ectopic dysgenetic cortex was associated with a grey matter pattern within the white matter territory, and was detected by SPM as areas of PET hypermetabolism and MRI hyperintensity. In order to detect possible metabolic changes undetected by the individual analyses, the group of patients was compared with the control group. This comparison revealed bilateral hypometabolism in the frontal opercular cortex. We propose that these PET data be considered in light of the presumed cyto-architectonic pattern of perisylvian dysgenesis, i.e. polymicrogyria. In this malformation, two dense cell layers are separated by a necrotic sparse cell layer. We speculate that the amount of synaptic activity preserved in these dense cell layers depends on the importance and timing of the necrotic process; this hypothesis accounts for the large range of metabolic patterns found, from profoundly decreased glucose metabolism to nearly normal activity.

Radiation induced renal cell cancer: a report of 4 cases and review of the literature

PURPOSE

During clinical care in the University of Chicago renal cell carcinoma program there was 1 case of prior radiation therapy for a neuroblastoma (patient age 16 months). After this index case was found our investigation was conducted to identify other cases with apparent radiation therapy induced renal cell carcinoma and review the literature on the subject.

MATERIALS AND METHODS

The clinical summaries of 573 cases from the University of Chicago renal cell carcinoma program from 1992 through 1998 were reviewed.

RESULTS

Four cases (3 men and 1 woman) of renal cell carcinoma, including the index case, were identified with prior therapeutic radiation therapy. Of the patients 3, 32, 35 and 36 years old, had been radiated for neuroblastoma 31, 32 and 35 years, respectively, before diagnosis of renal cell carcinoma and 1 (age 64 years) had been radiated for testicular seminoma 25 years earlier. The 32-year-old patient had 2 primary renal cell carcinomas in the remaining kidney and an associated leiomyosarcoma. He was alive and disease-free on dialysis 8 years after diagnosis. The 35-year-old patient had localized well differentiated renal cell carcinoma and was disease-free for 24 months. The 36-year-old patient had relapse 7 years after nephrectomy and had progressive refractory disease 12 years after diagnosis. The 64-year-old patient had relapse in 2.5 years but was alive with metastatic disease 4 years later. A literature review documented 4 other patients with renal cell carcinoma of those with neuroblastoma treated with radiation therapy.

CONCLUSIONS

Radiation therapy induced renal cell carcinoma is rare (less than 1% of renal cell carcinoma cases), and in our 4 cases it occurred 25 to 35 years after radiation. The risk of renal cell carcinoma should be considered during long-term followup of patients exposed to radiation therapy.

Does glucose affect fertilization, development and pregnancy rates of human in-vitro fertilized oocytes?

The study was conducted to examine whether the presence of glucose in the incubation medium affects fertilization, development and implantation rates of human oocytes of patients who were attending our in-vitro fertilization programme. Harvested oocytes were transferred into one of four different media: human tubal fluid (HTF), P1, M3 and IVF-Universal (IVF-Med). Three of these contained glucose; the fourth (P1), contained no glucose or phosphate ions. In an independent preliminary study, some of the oocytes of each patient were incubated in IVF-Med, which lacks phosphate ions, but not glucose. Comparisons of fertilization rates between media pairs showed differences among all pairs except HTF and M3. When comparing the four study groups, no difference was noticed in embryo development or embryo quality 48 h post-ovum retrieval. A higher development rate was demonstrated in embryos incubated in M3 medium, in comparison with the P1 and IVF-Med embryos after incubation for 72 h. No difference in pregnancy rate was found after embryo transfers of preimplantation embryos which were incubated in one of the following media: HTF, M3 and IVF-Med (seven out of 22, 18 of 54 and 32 of 69 treatment cycles respectively). A lower incidence of pregnancies occurred following transfers of embryos which were incubated in P1 medium (seven pregnancies out of 37 cycles). We suggest that the presence of glucose in the incubation medium enhances implantation potential of in-vitro-developing preimplantation embryos.

[Sexually transmitted infection as a cause of anal cancer]

Interviews were carried out with 423 women and 93 men with invasive or in situ anal cancer in Denmark and Sweden in a search for clues to the aetiology of this neoplasm. Patients with rectal adenocarcinoma (n = 534) and persons drawn from the background population (n = 554) served as controls. Multivariate logistic regression analyses confirmed previous observations of a strong association between either male homosexual experience or a history of anogenital warts and the risk for anal cancer. Moreover, hitherto unknown, but strong and consistent associations were observed between measures of high heterosexual activity and the risk for anal cancer among both sexes. Polymerase chain reaction analysis revealed human papilloma-virus DNA in the majority (88%) of anal cancer specimens but in none of 20 examined rectal adenocarcinomas. It is concluded that most anal cancers appear to be caused by sexually transmitted types of human papillomaviruses and, consequently, that anal cancer is a potentially preventable neoplasm.

Antithrombotic therapy in patients with saphenous vein and internal mammary artery bypass grafts

Aspirin (325 and 900 mg/d) is effective for a period of 1 year in reducing the frequency of saphenous vein bypass graft occlusion when begun 1 day before operation or on the day of operation. Aspirin in combination with dipyridamole is not more effective than aspirin alone in the prevention of saphenous vein graft occlusion. Bleeding is higher among patients treated with aspirin (325 mg/d) than among controls if aspirin is started 1 day before operation. Bleeding in one trial was greater than controls if aspirin (300 mg/d) was started the day of operation, and in one trial there was no difference when aspirin (325 mg/d) was started the day of operation. Ticlopidine (500 mg/d), started 2 days after operation, was effective in maintaining graft patency. Oral anticoagulants were inconsistent in the maintenance of saphenous vein graft patency. The continued use of aspirin for 2 additional years after an initial year of aspirin therapy for the prevention of saphenous vein bypass graft occlusion showed no additional long-term benefit on graft patency at the end of the third year. Antithrombotic agents given to patients with internal mammary artery bypass grafts showed no benefit in comparison to placebo because patency on placebo was high.

Hearing results of intratympanic steroid treatment of endolymphatic hydrops

OBJECTIVES/HYPOTHESIS

This study evaluated the effectiveness of a single application of steroids to the open middle ear in improving short-term hearing in patients with Meniere's disease and cochlear hydrops.

STUDY DESIGN

Retrospective study in which each patient's pretreatment hearing served as the control compared with posttreatment hearing.

METHODS

Patients were treated with a single application of dexamethasone, 8 mg, in hyaluronan. Following tympanotomy and lysis of round window adhesions, steroids were placed in the round window niche with absorbable gelatin sponge and the remainder of the middle ear was then filled with the steroid solution. Systemic steroids were not administered. Audiograms were performed within 1 month before surgery and at least 1 month after surgery.

RESULTS

Between September 1996 and July 1997, 21 ears in 19 patients underwent intratympanic steroid treatment. The criterion for hearing change was a 10-dB or greater change in pure-tone average (PTA), or a 15% change in speech discrimination score (SDS). Of the 15 ears meeting inclusion criteria for this study, five (33%) demonstrated hearing improvement and three (20%) demonstrated hearing deterioration. Maximum improvement was a 38-dB improvement in PTA and a 32% improvement in SDS.

CONCLUSION

A single application of intratympanic dexamethasone/hyaluronan solution directly to the round window did not produce dramatic short-term hearing improvement in patients with endolymphatic hydrops. Although the theoretical basis for intratympanic steroid treatment of endolymphatic hydrops is appealing, we urge close evaluation of the results of specific protocols of intratympanic steroid administration before widespread utilization of this treatment. The choice of steroid, route of administration, frequency of application, and need for simultaneous systemic administration require standardization to adequately assess the efficacy of this treatment.

Gap-junction-mediated propagation and amplification of cell injury

Gap junctions are conductive channels that connect the interiors of coupled cells. We determined whether gap junctions propagate transcellular signals during metabolic stress and whether such signaling exacerbates cell injury. Although overexpression of the human proto-oncogene bcl2 in C6 glioma cells normally increased their resistance to injury, the relative resistance of bcl2+ cells to calcium overload, oxidative stress and metabolic inhibition was compromised when they formed gap junctions with more vulnerable cells. The likelihood of death was in direct proportion to the number and density of gap junctions with their less resistant neighbors. Thus, dying glia killed neighboring cells that would otherwise have escaped injury. This process of glial 'fratricide' may provide a basis for the secondary propagation of brain injury in cerebral ischemia.

Purification, crystallization and preliminary X-ray crystallographic analysis of Pyrococcus furiosus DNA polymerase

DNA polymerase gene from the hyperthermophilic Archaeon Pyrococcus furiosus has been cloned and the protein overexpressed in Escherichia coli to produce an active enzyme. The purified protein was crystallized from 0.08 M ammonium sulfate, 0.05 M Na-cacodylate, pH 6.5, 0.15%(v/v) NP40, 0.05%(v/v) Tween 20 and 4.5%(w/v) polyethylene glycol 6000 by the vapour-diffusion method. The orthorhombic crystals had unit-cell dimensions of a = 92.5, b = 125.4, c = 192.1 A; alpha = beta = gamma = 90 degrees. The crystals diffracted beyond 4 A on a 1.08 A synchrotron radiation source.