Catecholamine sensitivity in the rat femoral artery after microvascular anastomosis

Tissue can demonstrate vasospastic instability after microvascular anastomosis. This study investigates the in vitro effect of increasing concentrations of phenylephrine on the rat femoral artery after microvascular anastomosis. Bilateral groin flaps based on the inferior epigastric artery were raised on 55 Wistar male rats. On the test side, a microvascular anastomosis was performed, but not on the control side. On days 2-12 postoperatively, the rats were sacrificed and the femoral arteries harvested and suspended in increasing concentrations of phenylephrine. The vascular tone on the test and control sides were recorded and compared. Increased sensitivity was found on the test side as compared with the control side (P = 0.000). This supersensitivity to phenylephrine was blocked by the addition of phentolamine and it is believed to be the result of sympathetic denervation, which occurs when the sympathetic fibers are cut during the harvesting of the flap. The resulting vascular instability is believed to contribute to flap failure.

Neuropathological correlates of dysarthria in progressive supranuclear palsy

BACKGROUND

The dysarthria of progressive supranuclear palsy consists of prominent hypokinetic and spastic components with less prominent ataxic components.

OBJECTIVE

To correlate the types of dysarthria with neuropathological changes in patients with progressive supranuclear palsy.

DESIGN AND METHODS

In 14 patients with progressive supranuclear palsy, we correlated the perceptual speech findings with the neuropathological findings. A dysarthria assessment was performed a mean +/- SD of 31 +/- 15 months (range, 10-53 months) before death. The deviant speech dimensions were rated on a scale of 0 (normal) to 3 (severe). The neuropathological examination consisted of semiquantitative analysis of neuronal loss and gliosis by investigators (A.A.F.S., and L.A.B.) blinded to the clinical findings. Correlation and linear regression analysis were used to correlate the severity of the hypokinetic, spastic, and ataxic components with the degree of neuronal loss and gliosis in predetermined anatomical sites.

RESULTS

All patients had hypokinetic and spastic dysarthria, and 9 also had ataxic components. The severity of the hypokinetic components was significantly correlated with the degree of neuronal loss and gliosis in the substantia nigra pars compacta (r = 0.61, P =.02) and pars reticulata (r = 0.64, P =.01) but not in the subthalamic nucleus (r = 0.51, P =.07) or the striatum or globus pallidus (/r/<0.34, P>.20). The severity of the spastic and ataxic components was not significantly correlated with the neuropathological changes in the frontal cortex (r = 0.20, P =.50) and cerebellum (/r/<0.28, P>.33), respectively.

CONCLUSION

The hypokinetic dysarthria of progressive supranuclear palsy may result from degenerative changes in the substantia nigra pars compacta and pars reticulata and not from changes in the striatum or globus pallidus.

Concerted inhibition of the transcriptional activation functions of the enhancer-binding protein NIFA by the anti-activator NIFL

The Azotobacter vinelandii NIFL regulatory flavoprotein responds to the redox, energy and nitrogen status of the cell to inhibit transcriptional activation by the sigmaN-dependent enhancer binding protein, NIFA, via the formation of a NIFL-NIFA protein complex. The NIFA protein contains three domains: an N-terminal domain of unknown function; a central catalytic domain required to couple nucleotide hydrolysis to activation of the sigmaN-RNA polymerase holoenzyme; and a C-terminal DNA-binding domain. We report that truncated NIFA proteins that either lack the amino-terminal domain or contain only the isolated central domain remain responsive to inhibition by NIFL but, in contrast to native NIFA, continue to hydrolyse nucleotides when NIFL is present. We also report that NIFL is competent to inhibit the DNA-binding function of NIFA. Taken together, these results suggest that NIFL inhibits NIFA via a concerted mechanism in which DNA binding, catalytic activity and, potentially, interaction with the polymerase are controlled by NIFL in order to prevent transcriptional activation under detrimental environmental conditions.

Signal transduction to the Azotobacter vinelandii NIFL-NIFA regulatory system is influenced directly by interaction with 2-oxoglutarate and the PII regulatory protein

PII-like signal transduction proteins, which respond to the nitrogen status via covalent modification and signal the carbon status through the binding of 2-oxoglutarate, have been implicated in the regulation of nitrogen fixation in several diazotrophs. The NIFL-NIFA two-component regulatory system, which integrates metabolic signals to fine-tune regulation of nitrogenase synthesis in Azotobacter vinelandii, is a potential target for PII-mediated signal transduction. Here we demonstrate that the inhibitory activity of the A.vinelandii NIFL protein is stimulated by interaction with the non-uridylylated form of PII-like regulatory proteins. We also observe that the NIFL-NIFA system is directly responsive to 2-oxoglutarate. We propose that the PII protein signals the nitrogen status by interaction with the NIFL-NIFA system under conditions of nitrogen excess, and that the inhibitory activity of NIFL is relieved by elevated levels of 2-oxoglutarate when PII is uridylylated under conditions of nitrogen limitation. Our observations suggest a model for signal transduction to the NIFL-NIFA system in response to carbon and nitrogen status which is clearly distinct from that suggested from studies on other diazotrophs.

Evolution of sporadic olivopontocerebellar atrophy into multiple system atrophy

OBJECTIVE

To determine the percentage of sporadic olivopontocerebellar atrophy (sOPCA) patients who later develop multiple system atrophy (MSA).

METHODS

Observations of the course of 51 sOPCA patients 20 years of age or older initially evaluated in an ataxia clinic over 14 years and followed at 3- to 6-month intervals for 3 months to 10 years (median 2.5 years, interquartile range 5 months to 4 years).

RESULTS

Seventeen patients evolved to develop MSA, whereas the remaining 34 manifested only progressively worsening cerebellar ataxia. The features of the MSA cases included autonomic failure and parkinsonism in 10 patients, autonomic failure without parkinsonism in six, and parkinsonism without autonomic failure in one. Using survival analysis methods, the authors estimated that 24% of subjects in this population will evolve to MSA within 5 years of the onset of sOPCA symptoms (95% CI 10% to 36%). An older age at onset of symptoms and a shorter time from onset of symptoms to first presentation in a neurology specialty clinic were both highly predictive of evolution to MSA. Six of the 17 patients who evolved to MSA died 4 months to 5 years after they had met diagnostic criteria for MSA. The estimated median survival time from time of transition was 3.5 years. In contrast, death occurred in only one of the 34 patients with sOPCA who did not evolve to MSA. Autopsy examination of all six patients with MSA who died confirmed the diagnosis.

CONCLUSIONS

Approximately one-fourth of sporadic olivopontocerebellar atrophy patients will evolve to multiple system atrophy within 5 years, and this transition carries a poor prognosis for survival. Older age at onset of ataxia and earlier presentation in a neurologic specialty clinic predicted transition to MSA.

PET measures of benzodiazepine receptors in progressive supranuclear palsy

OBJECTIVE

To evaluate the integrity of neurons containing benzodiazepine receptors in metabolically affected regions of the brain in patients with clinically diagnosed progressive supranuclear palsy (PSP).

METHODS

The cerebral distribution of [11C]flumazenil (FMZ), a ligand that binds to the gamma-aminobutyric acid A (GABAA) receptor, and [18F]fluorodeoxyglucose (FDG), a measure of local cerebral glucose metabolism, was determined with PET in 12 patients with PSP and 10 normal control subjects. Tracer kinetic analysis was applied to quantify data and analysis was performed using three-dimensional stereotactic surface projections and stereotactically determined volumes of interest.

RESULTS

There was a global reduction in FMZ binding of 13%, with a reduction in the anterior cingulate gyrus of 20% (p = 0.004), where glucose metabolic rates also showed the greatest reduction.

CONCLUSIONS

PSP causes loss of benzodiazepine receptors in the cerebral cortex. Consistent with postmortem studies, the authors did not find significant changes in FMZ binding in subcortical nuclei that exhibit the most pathologic change. This study suggests that both loss of intrinsic neurons containing benzodiazepine receptors and deafferentation of the cerebral cortex from distant brain regions contribute to cerebral cortical hypometabolism in PSP.

Decreased striatal monoaminergic terminals in multiple system atrophy detected with positron emission tomography

We examined the density of striatal presynaptic monoaminergic terminals, using a ligand for the type 2 vesicular monoamine transporter, (+)-[11C]dihydrotetrabenazine, with positron emission tomography in 7 normal control subjects, 8 multiple system atrophy (MSA) patients with predominantly parkinsonian features (MSA-P), 8 MSA patients with principally cerebellar dysfunction (MSA-C), and 6 sporadic olivopontocerebellar atrophy (sOPCA) patients. The findings were correlated with the results of neurological evaluations and magnetic resonance imaging studies. Specific binding was significantly reduced in the putamen of all patient groups in the order MSA-P < MSA-C < sOPCA, compared with controls. Mean blood-to-brain ligand transport (K1) was significantly decreased in the putamen of all patient groups and in the cerebellar hemispheres of MSA-C and sOPCA but not MSA-P groups, compared with controls. Significant negative correlations were found between striatal binding and the intensity of parkinsonian features and between cerebellar K1 and the intensity of cerebellar dysfunction. The results suggest fundamental differences between MSA-P and MSA-C groups reflecting differential severity of degeneration of nigrostriatal and cerebellar systems in these two forms of MSA. The findings also show that some sOPCA patients have subclinical nigrostriatal dysfunction and are at risk of developing MSA with disease progression.

What is hemoglobin A1c? An analysis of glycated hemoglobins by electrospray ionization mass spectrometry

Hemoglobin A1c (HbA1c) is a stable minor Hb variant formed in vivo by posttranslational modification by glucose, originally identified by using cation exchange chromatography, and containing primarily glycated N-terminal beta-chains. However, the structure(s) of the quantified species has not been elucidated, and the available methods lack a reference standard. We used electrospray ionization mass spectrometry to determine the extent of glycation of samples separated by boronate affinity and/or cation exchange chromatography. Analyses of clinical samples were consistent with the curvilinear relationship of patient glucose and HbA1c. As glycation increased, the ratio of beta-chain to alpha-chain glycation increased, and the number of glycation sites on the beta-chain increased, although these were relatively minor components. We found several glycated species that cochromatographed with HbA1c on cation exchange, including species with both glycated alpha- and beta-chains, nonglycated alpha- and glycated beta-chains, and multiply glycated beta-chains. The combined use of affinity and cation exchange chromatography with structural confirmation by electrospray ionization mass spectrometry was found to be useful in producing samples of sufficient purity for the standardization of glycohemoglobin clinical assays.

A simple high performance liquid chromatography assay for simultaneous determination of omeprazole and metronidazole in human plasma and gastric fluid

Antibiotics which are actively secreted into gastric fluid may be more efficacious in the eradication of Helicobacter pylori in peptic ulcer disease. Other agents used in the treatment of this disease such as omeprazole or other anti-secretory agents may alter the secretion and/or distribution characteristics of antibiotics. In order to test the applicability of these concepts to metronidazole, a sensitive and specific high performance liquid chromatography (HPLC) assay was developed to quantitate omeprazole in plasma, and metronidazole in plasma and gastric fluid. The HPLC system consisted of a multi-phase column combining anion exchange and reversed phase separation (OmniPac Pax-500, Dionex), and a variable wavelength UV detector set at 254 nm. The mobile phase was a mixture of 0.1 M sodium phosphate buffer:methanol:acetonitrile (60:20:20) with final pH adjusted to approximately 7.0. Metronidazole and omeprazole were extracted by adsorption onto a C2-bonded silica gel solid phase extraction column, and eluted with methanol. The extract was dried, reconstituted in a solution of acetyl salicylic acid (ASA), and then injected into the HPLC system. Under these conditions, metronidazole, omeprazole and ASA were well separated and recoveries in plasma were greater than 80%. Omeprazole could not be measured in gastric fluid because of rapid decomposition. Using 0.3 ml of sample, the assay sensitivity was less than 0.1 microgram ml-1 and linear up to 10 micrograms ml-1. Both intra- and inter-assay CV were greater than 15%. It was applied successfully in determining metronidazole concentrations in clinical samples of plasma and gastric fluid.

Phase II and dose-escalation with or without granulocyte colony-stimulating factor study of 9-aminocamptothecin in relapsed and refractory lymphomas

PURPOSE

To assess the efficacy and maximum dose-intensity of a new topoisomerase I (topo I)-targeting agent, 9-aminocamptothecin (9-AC), in patients with relapsed or refractory lymphomas.

PATIENTS AND METHODS

Eligible patients had measurable disease and were considered incurable. 9-AC was infused over 72 hours at an initial dose rate of 40 microg/m2/h every 3 weeks with subsequent intrapatient escalations or reductions in 10-microg/m2/h increments based on toxicity. To assess the impact of granulocyte-colony stimulating factor (G-CSF) on dose-intensity, the first 16 patients received no G-CSF and the subsequent 29 patients received G-CSF on all cycles.

RESULTS

Forty-five patients received a total of 142 cycles of 9-AC. The patients' median age was 55 years, 73% had stage IV disease, and histologies included indolent and aggressive non-Hodgkin's lymphoma (NHL) in 33% and 58% of patients, respectively, and Hodgkin's lymphoma in 9%. Patients had received a median of two prior chemotherapy regimens, and 67% of patients had chemotherapy-sensitive disease. Of 40 assessable patients, 10 (25%) achieved a partial response (PR). Chemotherapy-sensitive patients had a 32% response rate compared with 8% in chemotherapy-resistant patients. With a median follow-up duration of 35 months, the median event-free survival (EFS) and overall survival times were 1.5 and 12.5 months, respectively, and the median duration of response was 5 months (range, 1 to 10). G-CSF significantly reduced the incidence of neutropenia and diarrhea, but did not permit a significant increase in dose-intensity.

CONCLUSION

9-AC had a reasonable response rate of 25% in heavily pretreated patients. The low response rate in patients with chemotherapy-resistant disease suggests that there is cross-resistance between 9-AC and standard chemotherapy. However, there was no association between 9-AC response and the number of prior regimens. Due to dose-limiting thrombocytopenia, G-CSF support did not increase dose-intensity, although individual patients benefited from the use of G-CSF.

Successful medical management of isolated renal zygomycosis: case report and review

We describe the medical management of isolated renal zygomycosis in an adult patient with AIDS during chemotherapy for AIDS-related lymphoma. After initial presentation during the first cycle of chemotherapy, the infection was contained within the kidney following recovery of the neutrophil count without medical or surgical intervention. Since he was not considered to be a candidate for nephrectomy, his infection was treated with amphotericin B lipid complex during subsequent chemotherapy. Neutropenia was minimized by the addition of cytokine support therapy with granulocyte colony-stimulating factor and reduced doses of chemotherapy. Following this strategy, his lymphoma completely resolved, and renal zygomycosis was controlled. At the time of this writing, he had been in complete remission for 18 months without evidence of progressive fungal infection. This report and our literature review indicate that isolated renal zygomycosis can be associated with a favorable prognosis, occurs with greatest frequency in patients with AIDS, is associated with parenteral access, and may be managed by medical therapy alone.

Vinblastine for recurrent Hodgkin's disease following autologous bone marrow transplant

PURPOSE

Bone marrow transplant (BMT) can cure recurrent Hodgkin's disease, but more than half of patients will progress and require additional treatment. When this occurs, there are no curative options and palliative therapy is usually indicated. In such patients, we have routinely used long-term vinblastine therapy because of its relatively low toxicity and high activity.

PATIENTS AND METHODS

We retrospectively reviewed the charts of all patients with Hodgkin's disease who relapsed after autologous BMT since 1991. Of 23 patients, 16 received vinblastine; we also include our index case, who began vinblastine following relapse in 1987. Patients received vinblastine 4 to 6 mg/m2 every 1 to 2 weeks, and continued until evidence of disease progression.

RESULTS

The 17 patients in this report had a median age of 31 years, performance status of 2, had received a median of three prior regimens, and 12 (71%) patients were advanced stage. Ten (59%) patients had objective responses, of which two (12%) were complete (CR) and eight (47%) were partial (PR). Two additional patients without measurable disease clinically improved for more than 6 months, and 1 patient had stable disease for more than 18 months. With a median follow-up of 20.4 months, the median event-free (EFS) and overall survival were 8.3 and 38.8 months, respectively. The two complete responders remain in remission at 4.6+ and 9+ years. Vinblastine was well tolerated with 3% of cycles associated with fever and neutropenia, and no cumulative or chronic toxicity.

CONCLUSION

Vinblastine provides effective palliation with low toxicity in recurrent Hodgkin's disease following transplant. These results suggest that long-term vinblastine therapy may be potentially curative and should be considered as initial therapy for such patients.

Allelic imbalance, including deletion of PTEN/MMACI, at the Cowden disease locus on 10q22-23, in hamartomas from patients with Cowden syndrome and germline PTEN mutation

Cowden disease (CD) is a rare, autosomal dominant inherited cancer syndrome characterized by multiple benign and malignant lesions in a wide spectrum of tissues. While individuals with CD have an increased risk of breast and thyroid neoplasms, the primary features of CD are hamartomas. The gene for CD has been mapped by linkage analysis to a 6 cM region on the long arm of chromosome 10 at 10q22-23. Loss of heterozygosity (LOH) studies of sporadic follicular thyroid adenomas and carcinomas, both component tumors of CD, have suggested that the putative susceptibility gene for CD is a tumor suppressor gene. Somatic missense and nonsense mutations have recently been identified in breast, prostate, and brain tumor cell lines in a gene encoding a dual specificity phosphatase, PTEN/MMACI, mapped at 10q23.3. Furthermore, germline PTEN/MMACI mutations are associated with CD. In the present study, 20 hamartomas from 11 individuals belonging to ten unrelated families with CD have been examined for LOH of markers flanking and within PTEN/MMACI. Eight of these ten families have germline PTEN/MMACI mutations. LOH involving microsatellite markers within the CD interval, and including PTEN/MMACI, was identified in two fibroadenomas of the breast, a thyroid adenoma, and a pulmonary hamartoma belonging to 3 to 11 (27%) of these patients. The wild-type allele was lost in these hamartomas. Semi-quantitative PCR performed on RNA from hamartomas from three different tissues from a CD patient suggested substantial reduction of PTEN/MMACI RNA levels in all of these tissues. The LOH identified in samples from individuals with CD and the suggestion of allelic loss and reduced transcription in hamartomas from a CD patient provide evidence that PTEN/MMACI functions as a tumor suppressor in CD.

An investigation of the effect of paternal occupation group at conception on birth weight and gestational age. ALSPAC Study Team of Pregnancy and Childhood

The occupational histories of fathers were collected prospectively as part of the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC), and were used to investigate the association of paternal job title with a baby's birth weight and gestational age. The analysis cohort consisted of 4,795 singleton live-born babies whose fathers responded fully to questionnaire items regarding occupational history. Jobs were coded using the British Standard Occupational Codes and classified into nine major occupational groups. A 73-gram difference (95% CI: 0.16, 145.17) was found between the mean birth weight of full-term babies born of professional fathers (3,543 gm) and of fathers working in craft and related occupations (3,470 gm). This difference decreased and lost significance after controlling for sociodemographic variables. No difference was found in the mean birth weight of preterm babies, or in the rate of preterm delivery, when analyzed by paternal occupation at conception. Our results suggest that when important sociodemographic variables are known, the father's job title alone may not be a useful predictor of birth weight or preterm delivery.

Biochemical characterization of recombinant fusions of lipopolysaccharide binding protein and bactericidal/permeability-increasing protein. Implications in biological activity

The physiological response to endotoxin (lipopolysaccharide (LPS)) can be regulated by two closely related LPS-binding proteins, LPS-binding protein (LBP), which potentiates LPS' inflammatory activity via interaction with the monocytic antigen CD14, and bactericidal/permeability-increasing protein (BPI), which neutralizes LPS. Both proteins bind LPS with high affinity sites in their N-terminal domains, whereas interaction between LBP and CD14 is dependent upon the LBP C-terminal domain. We have created fusions of the N- and C-terminal domains from each protein and compared the functional activities and pharmacokinetics of these fusions, the individual N-terminal domains, and the parent proteins. The N-terminal domains of BPI and LBP bound lipid A with their characteristic apparent affinity constants, regardless of the C-terminal fusion partner. In addition, the C-terminal domain of LBP allowed transfer of LPS to CD14 in conjunction with either N-terminal LPS binding domain. Proteins containing a BPI N-terminal domain had greater heparin binding capacities in vitro and were cleared more rapidly from the plasma of whole animals. Taken together, these data better define how closely related proteins such as BPI and LBP can have opposing effects on the body's response to LPS.

Decreased striatal monoaminergic terminals in olivopontocerebellar atrophy and multiple system atrophy demonstrated with positron emission tomography

We used [11C]dihydrotetrabenazine, a new ligand for the type 2 vesicular monoamine transporter (VMAT2), with positron emission tomography to study striatal monoaminergic presynaptic terminals in 4 patients with multiple system atrophy, 8 with sporadic olivopontocerebellar atrophy, and 9 normal control subjects. Specific binding in the striatum was significantly reduced in the multiple system atrophy patients as compared with the normal control group, with average reductions of 61% in the caudate nucleus (p = 0.002) and 58% in the putamen (p = 0.009). Smaller reductions were found in the sporadic olivopontocerebellar atrophy group, averaging 26% in the caudate nucleus (p = 0.05) and 24% in the putamen (p = 0.11). Mean blood-to-brain [11C]dihydrotetrabenazine transport (K1) was significantly different between groups only in the cerebellum, with values for the sporadic olivopontocerebellar atrophy group diminished compared with the normal control group. Cerebellar K1 was not significantly decreased in the multiple system atrophy group. The finding of reduced striatal VMAT2 in sporadic olivopontocerebellar atrophy patients suggests nigrostriatal pathology, indicating that some may later develop symptomatic extrapyramidal disease.

Intent-to-treat analysis for longitudinal studies with drop-outs

We consider intent-to-treat (IT) analysis of clinical trials involving longitudinal data subject to drop-out. Common methods, such as Last Observation Carried Forward imputation or incomplete-data methods based on models that assume random dropout, have serious drawbacks in the IT setting. We propose a method that involves multiple imputation of the missing values following drop-out based on an "as treated" model, using actual dose after drop-out if this is known, or imputed doses that incorporate a variety of plausible alternative assumptions if unknown. The multiply-imputed data sets are then analyzed using IT methods, were subjects are classified by randomization group rather than by the dose actually received. Results from the multiply-imputed data sets are combined using the methods of Rubin (1987, Multiple Imputation for Nonresponse in Surveys). A novel feature of the proposed method is that the models for imputation differ from the model used for the analysis of the filled-in data. The method is applied to data on a clinical trial for Tacrine in the treatment of Alzheimer's disease.

The repeatability of self-reported exposure after miscarriage. ALSPAC Study Team. Avon Longitudinal Study of Pregnancy and Childhood

BACKGROUND

The Avon Longitudinal Study of Pregnancy and Childhood is a prospective study of women who were resident in Avon and who were expected to deliver a baby between April 1991 and December 1992.

METHODS

The study provided an opportunity to test the repeatability of responses from 220 women who experienced a miscarriage and who reported exposure to occupational substances and common household products and appliances in two questionnaires. The first questionnaire was completed in the early part of the pregnancy and the second after the miscarriage. Women were asked to score their frequency of exposure on a five-point scale from 'daily' to 'never'. Their responses were analysed to assess the degree of agreement between replies to identical questions in the two questionnaires using the kappa statistic. A new frequency variable was created which compared the replies for the two questionnaires; this was analysed for all exposures by cross-tabulation with possible explanatory variables (age of mother, social class, history of miscarriage and the time lag between questionnaires).

RESULTS

In general there was good agreement in the reported exposures to 48 substances and products. The results showed a small and consistent pattern of reporting exposures less frequently in the second questionnaire, i.e. after miscarriage. This was not explained by the analysis of possible confounding variables. Given the literature, the authors had expected to find a shift in the opposite direction.

CONCLUSION

The study reinforces the need to be cautious when using the results from single surveys of retrospective self-reported exposure.