Directions in HIV/AIDS research. A Minnesota perspective

Clinical studies involving HIV therapeutics are becoming ever more challenging because of the changing epidemiology of HIV infection, the rapid evolution of standard clinical practice, and a more difficult economic environment for research. Recent studies relating to HIV pathogenesis have provided novel insights into the interactions between HIV, the immune system, and antiretroviral therapies. Current dogma now suggests that the interaction of HIV and the immune system is an incredibly dynamic process. HIV is an intimidating pathogen capable of replicating quickly and mutating very rapidly in response to antiretroviral therapy. An important question being studied by Minnesota-based investigators is how well plasma analysis reflects HIV-immune system interactions in the lymphoid tissue where most virus and CD4+ (T-helper) cells are located. Most of the HIV clinical studies in Minnesota are conducted under the auspices of the AIDS Clinical Trials Group (ACTG) or the AIDS Research Consortium of the Twin Cities (ARCTiC). Much expertise is available in Minnesota addressing a wide range of topics, from epidemiology, to basic virology, to prevention. To optimize patient access to clinical studies, we recommend that physicians discuss available clinical studies with an HIV investigator soon after first seeing a new HIV-infected patient.

Effectiveness of adjunct therapies in crack cocaine treatment

Although intensive outpatient therapy is recommended for treatment of cocaine, psychosocial characteristics associated with crack cocaine abuse are also implicated in attrition from outpatient programs. Acupuncture, medications, and brainwave therapy (biofeedback), have all been used to encourage treatment retention and drug use outcomes. The effectiveness of three adjunct therapies in improving retention and drug use outcomes in intensive outpatient cocaine treatment was tested in a primarily young, indigent African-American sample of crack cocaine users at a community hospital in a low-income, high drug use neighborhood in Houston. Subjects were assigned to receive either neurobehavioral treatment alone or neurobehavioral with one of three adjunct therapies. These included acupuncture, anticraving medication, or brainwave therapy. Comparative results indicated that dosage of any adjunct therapy was associated with days in treatment and standard treatment sessions attended, and that standard treatment sessions attended was associated with negative urinalysis results at follow-up. None of the adjunct therapies were directly associated with drug use outcomes.

Recombinant human erythropoietin therapy for anemic cancer patients receiving cisplatin chemotherapy

PURPOSE

To assess whether the administration of recombinant human erythropoietin (r-HuEPO) would increase the hematocrit, reduce the requirement for transfusion, and improve the quality of life in anemic cancer patients receiving myelosuppressive, cisplatin-based chemotherapy.

PATIENTS AND METHODS

One hundred thirty-two anemic cancer patients receiving cyclic, cisplatin-containing, myelosuppressive chemotherapy were evaluated. Patients received either r-HuEPO (150 U/kg) or placebo, subcutaneously, three times a week for 3 months. Responses were assessed by measuring changes in hemoglobin/hematocrit, transfusion requirement, and quality of life.

RESULTS

The mean hematocrit increased by 6.0 percentage points in the r-HuEPO group versus 1.3 in the placebo group. A decrease in transfusion requirement did not reach significance over all 3 months, but there was a significant reduction in the percentage of patients transfused in the second and third months (27% r-HuEPO vs. 56% placebo) and a trend toward reduction in the mean total number of units transfused (1.20 units r-HuEPO vs. 2.02 units placebo), suggesting a lag of 1 month before r-HuEPO can affect the transfusion requirement. Pretreatment serum erythropoietin levels were lower in responders than in nonresponders (73.5 IU/L and 86.3 IU/L means, respectively). However, the magnitude of this difference was not helpful in defining which patients were likely to respond. There was a significant improvement in overall quality of life between the two treatment arms in favor of the r-HuEPO-treated group. There were no significant adverse effects associated with r-HuEPO.

CONCLUSIONS

r-HuEPO is safe and can cause a significant improvement in the hematocrit and quality of life of anemic cancer patients receiving myelosuppressive, cisplatin-based chemotherapy. After 1 month of r-HuEPO, there is also a reduction in transfusion requirement.

Dietary sodium intake modulates systemic but not forearm norepinephrine release

INTRODUCTION

Sodium intake has profound effects on systemic and renal sympathetic activity, but its effects on sympathetic activity in skeletal muscle vascular beds, a site at which local regulatory mechanisms could alter vascular tone directly, are unclear.

METHODS

To determine the effect of dietary sodium intake on basal and isoproterenol-stimulated systemic and forearm norepinephrine kinetics, we studied seven healthy male volunteers twice, 4 weeks apart, while they were receiving a low-sodium (10 mmol sodium/24 hours) diet and a high-sodium diet (250 mmol sodium/24 hours). Forearm blood flow, measured by plethysmography, and systemic and forearm norepinephrine spillover, measured by radioisotope dilution, were determined before and after intra-arterial infusion of 60 and 400 ng/min isoproterenol.

RESULTS

Baseline (before isoproterenol) systemic norepinephrine spillover was higher when subjects received the low-sodium diet (448.1 +/- 55.7 ng/min) compared with the high-sodium diet (269.7 +/- 42.7 ng/min; p < 0.05). In contrast, sodium intake did not affect local forearm norepinephrine spillover, either at baseline (low-sodium diet, 2.05 +/- 0.48 ng/min versus high-sodium diet, 2.63 +/- 0.79 ng/min; p = 0.50) or after stimulation with isoproterenol in doses of 60 ng/min (low-sodium diet, 8.84 +/- 2.2 ng/min versus high-sodium diet, 6.1 +/- 1.9 ng/min; p = 0.38) or 400 ng/min (low-sodium diet, 16.4 +/- 4.5 ng/min versus high-sodium diet, 16.7 +/- 2.5 ng/min; p = 0.93).

CONCLUSIONS

Under conditions of low sodium intake, systemic norepinephrine spillover was increased but forearm norepinephrine spillover was not, suggesting that alteration in sodium intake may produce a differential effect on norepinephrine spillover in different tissues but that decreased local sympathetic activity in skeletal muscle is not the likely mechanism by which a low-sodium diet may lower blood pressure or attenuate stress-induced pressor responses.

Sterilization with methyl cyanoacrylate-induced fallopian tube occlusion from a nonsurgical transvaginal approach in rabbits

PURPOSE

To evaluate a nonsurgical, nonhormonal sterilization procedure performed with use of transvaginal microcatheterization techniques and methyl cyanoacrylate (MCA) as a sclerosing agent

MATERIALS AND METHODS

Seventeen adult virgin female rabbits underwent bilateral fallopian tube cannulation through a nonsurgical transvaginal approach with use of a coaxial catheter system with fluoroscopic guidance. Fourteen of the rabbits underwent bilateral fallopian tube occlusion with direct MCA injection; the remaining three rabbits were separated as controls. Three of the rabbits with occlusions were killed as temporal histologic controls. The remaining 11 rabbits with occlusions and the initial three controls underwent 6 months of mating trials. All 17 rabbits were killed. Gross inspection was performed and histologic specimens of their fallopian tubes were obtained.

RESULTS

None of the 11 rabbits with occlusions that underwent mating became pregnant. All three control rabbits became pregnant. Histologic examination of the occluded fallopian tubes demonstrated long-segment tubal wall fibrosis with varying degrees of occlusion. No peritoneal abnormalities were identified. Histologic findings for the three control animals were normal.

CONCLUSION

With use of a nonsurgical transcervical coaxial catheter system, MCA can be placed directly into fallopian tubes without difficulty. MCA administration leads to fallopian tube fibrosis and occlusion. A 100% nonpregnancy rate was demonstrated. Further investigation may lead to a safer, more convenient, and less expensive form of permanent sterilization.

Community-based prevalence of anal incontinence

OBJECTIVE

To determine the prevalence of and characteristics associated with anal incontinence in the general community.

SETTING

Community survey.

PARTICIPANTS

The population of the state of Wisconsin sampled in the Wisconsin Family Health Survey. Subjects were identified by random digit dialing with telephone interview. The individual within each household identified as most knowledgeable about the health status of all other members of the household was asked about the health status of each member of the household. Approximately 200 households were surveyed each month.

MAIN OUTCOME MEASURES

The presence of anal incontinence to solid or liquid feces or gas, who suffered from it, the frequency of anal incontinence, and how the incontinent person coped with it.

RESULTS

A total of 2570 households comprising 6959 individuals were surveyed, and 153 individuals were reported to have anal incontinence, representing 2.2% of the population (95% confidence interval [Cl], +/- 0.3%). Thirty percent of the incontinent subjects were older than 65 years, and 63% were women. Of those with anal incontinence, 36% were incontinent to solid feces, 54% to liquid feces, and 60% to gas. In a multivariate analysis, independent associations of the following risk factors with anal incontinence were found: female sex (odds ratio [OR], 1.5; Cl, 1.1 to 2.1), age (continuously adjusted) (OR, 1.01; Cl, 1.01 to 1.02), physical limitations (OR, 1.8; Cl, 1.2 to 2.7), and poor general health (OR, 1.6; Cl, 1.4 to 1.9).

CONCLUSIONS

Anal incontinence was reported in 2.2% of the general population. Independent risk factors for incontinence include female sex, advancing age, poor general health, and physical limitations.

Formation of ion channels in lipid bilayers by a peptide with the predicted transmembrane sequence of botulinum neurotoxin A

Synthetic peptides patterned after the predicted transmembrane sequence of botulinum toxin A were used as tools to identify an ion channel-forming motif. A peptide denoted BoTxATM, with the sequence GAVILLEFIPEIAI PVLGTFALV, forms cation-selective channels when reconstituted in planar lipid bilayers. As predicted, the self-assembled conductive oligomers express heterogeneous single-channel conductances. The most frequent openings exhibit single-channel conductance of 12 and 7 pS in 0.5 M NaCl, and 29 and 9 pS in 0.5 M KCl. In contrast, ion channels are not formed by a peptide of the same amino acid composition as BoTxATM with a scrambled sequence. Conformational energy calculations show that a bundle of four amphipathic alpha-helices is a plausible structural motif underlying the measured pore properties. These studies suggest that the identified module may play a functional role in the ion channel-forming activity of intact botulinum toxin A.

Attenuation of isoproterenol-mediated vasodilatation in blacks

BACKGROUND

The mechanism of enhanced vascular reactivity in young blacks, which may play a part in the development of hypertension, has not been defined. To determine the contribution of blunted vasodilatation mediated by beta 2-adrenergic receptors to this phenomenon, we compared forearm blood-flow responses to isoproterenol in young black and white normotensive men.

METHODS

We used venous-occlusion plethysmography to measure the responses of blood flow in the forearm to the intraarterial administration of isoproterenol (10 to 400 ng per minute) in 9 normotensive black men (mean [+/- SD] age, 31.3 +/- 8.0 years) and 13 normotensive white men (mean age, 32.9 +/- 5.6 years). Sympathetic activity in the forearm was measured simultaneously by isotope-dilution techniques.

RESULTS

Base-line blood flow in the forearm was similar in blacks and whites, but the degree of vasodilatation in response to isoproterenol was markedly lower in blacks. Isoproterenol at an infusion rate of 400 ng per minute produced a 9-fold increase in blood flow in whites but only a 3.5-fold increase in blacks (P < 0.001). The base-line rate of norepinephrine spillover in the forearm was higher in blacks (2.0 +/- 1.3 ng per minute [11.8 +/- 7.7 nmol per minute]) than in whites (0.6 +/- 0.5 ng per minute [3.5 +/- 3.0 nmol per minute], P = 0.002), but there was no difference between the groups after isoproterenol stimulation.

CONCLUSIONS

Forearm blood-flow responses to isoproterenol were markedly attenuated in normotensive blacks, indicating a blunting of vasodilatation mediated by beta 2-adrenergic receptors. Sympathetic activity in the forearm was greater in blacks than in whites, but isoproterenol-stimulated presynaptic beta 2-adrenergic responses (which facilitated norepinephrine release) did not differ significantly between blacks and whites. Our findings suggest that the mechanisms responsible for blunted vasodilatation in response to the administration of isoproterenol may contribute to enhanced vascular reactivity in blacks and may play a part in the pathogenesis of hypertension in blacks.

Functional role of GABA in cat retina: II. Effects of GABAA antagonists

Putative GABAergic mechanisms were studied in the cat retina by exogenous application of the GABAA antagonists picrotoxin (PTX), native bicuculline (BCC), and bicuculline methyl bromide (BCC MeBr). When recording intracellular responses from horizontal cells (HCs) and amacrine cells as well as electroretinograms (ERGs), drugs were added to the perfusate used to maintain the isolated eyecup; when recording extracellular spikes from ganglion cells of anesthetized cats, drugs were introduced by iontophoretic injection. Both PTX and BCC MeBr had relatively little influence upon the response properties of HCs. In contrast, native BCC tended to decrease the amplitude of and to slow the photic response to light onset and both to quicken and to increase the amplitude of response to light offset; in the presence of native BCC, HC responses were dominated by a prominent spike-like "Off-overshoot." The influence of GABAA agonists upon HC responses was not blocked by GABAA antagonists. ERG b-wave amplitude was reduced both by PTX and by native BCC, but was not influenced by BCC MeBr. Latency (time to half-peak) was increased by low doses of native BCC, and to a lesser extent PTX but not BCC MeBr. Rod-amacrine On-transient responses were increased in amplitude by PTX. Extracellular recordings from On- and Off- X and Y ganglion cell types became considerably more transient with application of either PTX, native BCC, or BCC MeBr; this tendency was greater in Off-type ganglion cells. Collectively, these results strengthen conclusions from the previous paper suggesting that GABA serves to slow onset and offset kinetics of retinal neurons, making them more sustained and less phasic. They also suggest that in mammalian retina heterogeneous types of GABAA receptors exist, segregated into different zones: a distal zone, sensitive only to native BCC, a central zone sensitive to both native BCC and PTX, and a proximal zone sensitive to native BCC, BCC methyl halides (BCC MeH), and PTX. Only the proximal zone obeys conventional GABAA pharmacology.

Forearm beta adrenergic receptor-mediated vasodilation is impaired, without alteration of forearm norepinephrine spillover, in borderline hypertension

Impaired beta adrenoceptor-mediated vasodilation associated with enhanced sympathetic activity has been reported in established hypertension. We examined whether altered beta adrenoceptor-mediated vasodilation occurs early in the disease process, when structural vascular changes are likely to be less marked, by measurement of forearm blood flow by strain gauge plethysmography after the intraarterial administration of increasing doses of a beta receptor agonist, isoproterenol, in eight subjects with borderline hypertension (BHT) and 13 normotensive (NT) controls. To determine the role of sympathetic activation in the regulation of responsiveness, we measured local sympathetic activity in the forearm by a radioisotope dilution technique. Vasodilation in response to isoproterenol, measured either as changes in forearm blood flow or forearm vascular resistance, was impaired in the BHT group so that flow at the highest dose of isoproterenol (400 ng/min) increased less (15.2 +/- 1.5 ml/100 ml per min) than in the NT group (24.4 +/- 2.4 ml/100 ml per minute) (P < 0.001). Although, systemic norepinephrine spillover was significantly greater in BHT, the difference in blood flow response to isoproterenol was not accounted for by increased local sympathetic activity since forearm norepinephrine spillover at baseline (BHT 1.0 +/- 0.4 ng/min vs. NT 0.64 +/- 0.13 ng/min) and after the administration of isoproterenol 60 ng/min (BHT 5.2 +/- 1.4 ng/min vs. NT 6.0 +/- 1.5 ng/min) and 400 ng/min (BHT 13.5 +/- 2.9 ng/min vs. NT 16.5 +/- 2.7 ng/min) did not differ between the two groups. We therefore conclude that vasodilation in response to isoproterenol is impaired in subjects with BHT and that this impairment is not explained by locally increased basal, or stimulated, sympathetic activity.

A pilot study of client progress in short-term drug abuse treatment

This paper is a pilot study of client progress in two short-term (23-day) drug abuse treatment programs. Client progress is defined as those changes in cognitive functioning, emotional well-being, and social support resources that are th proximate goals of drug abuse treatment. In this study, client progress was measured by changes in cognitive functioning, emotional well-being, and social support domains over the course of treatment. This pilot study showed that client progress can be detected in short-term treatment and can be related to indicators of the quantity and quality of treatment. In general, results showed that both relationships and emotional well-being changed over the course of treatment. Cognitive functioning variables did not generally change over time, nor were they related to indicators of treatment quality. Evidence in this pilot study suggests that more attention needs to be given to the relational and emotional aspects of the drug abuse treatment process.

Functional role of GABA in cat retina: I. Effects of GABAA agonists

Putative GABAergic mechanisms were studied in perfused cat retina by means of intracellular recording and application of GABA and the GABAA agonists delta-amino valeric acid (dAVA), muscimol, and THIP. In contrast to results reported previously for cold-blooded vertebrates, introduction of 20 mM GABA into the superfusate had no influence upon the response properties of cat retinal horizontal cells (HCs). In common with results reported in cold-blooded vertebrates, introduction of the GABAA agonists dAVA (2-12 mM) and THIP or muscimol (0.2-1 mM) had four consistent reversible influences upon the response properties of cat retinal HCs: (1) they reduced photic-response amplitude, (2) slowed response onset, (3) slowed response offset, and (4) depolarized the dark membrane potential. Both rod and cone signal components were affected. GABAA agonists had similar influences upon both the time course and amplitude of responses recorded from amacrine and ganglion cells. In all cell types examined, the influence upon response kinetics was made particularly apparent with rapidly flickering stimuli. Flicker responses were reduced in amplitude much more than sustained responses. These results suggest that, in addition to other influences, GABAergic action serves to modify the time course of photic responses in both the inner and outer plexiform layer of mammalian retina making responses slower and less phasic.

Comparison of the results of cemented, porous-ingrowth, and threaded acetabular cup fixation. A meta-analysis of the orthopaedic literature

A meta-analysis of the orthopaedic literature was performed to evaluate the clinical performance of cementless, threaded acetabular cups. The hypothesis for the study was that the clinical performance of the cementless, threaded acetabular cup is equivalent to that of the cemented and porous-ingrowth acetabular cups. Ninety-five articles were included in the study. There were 1,269 cases in the threaded cup group, 1,979 in the porous control group, and 10,230 in the cemented control group. The primary outcome variable tested was the rate of aseptic loosening of the acetabular components as measured by the revision rates following the index total hip arthroplasty procedure. Other measures of acetabular component loosening that were analyzed included clinical rating scores, pain scores, frequency of radiolucencies according to location and size, frequency of radiolucencies as a separately defined outcome variable, progressive radiolucencies, and component migration. The threaded cup group was found to have a significantly higher rate of revision, clinical and pain score failures, progressive radiolucencies and migrations when compared with the cemented and porous control groups (P < .05). Despite the many limitations of meta-analyses and the poor state of the orthopaedic literature database, this study provides a reasonable comparison of the clinical performance of threaded acetabular cups with that of cemented and porous-ingrowth acetabular cups.

Tachyphylaxis of human forearm vascular responses does not occur rapidly after exposure to isoproterenol

In vitro and limited in vivo data suggest that rapid desensitization of beta-adrenoceptor responses occurs after exposure to agonist. Tachyphylaxis to a beta-adrenoceptor agonist would represent a potentially important mechanism for the short-term regulation of vascular tone. The effects of a 4-hour infusion of 400 ng/min intra-arterial isoproterenol on forearm blood flow and presynaptic beta-adrenoceptor-mediated norepinephrine release were determined in eight healthy volunteers. Intra-arterial isoproterenol at 400 ng/min resulted in a significant increase in forearm blood flow in all eight subjects at all time points, with no evidence of tachyphylaxis. In fact, forearm blood flow after 4 hours of the isoproterenol infusion (22.8 +/- 3.3 mL/100 mL per minute) was significantly greater than after 7 minutes (14.6 +/- 2.8 mL/100 mL per minute), 15 minutes (15.4 +/- 2.4 mL/100 mL per minute), and 30 minutes (17.4 +/- 3.0 mL/100 mL per minute) of the infusion (P < .05). Similarly, presynaptic beta-adrenoceptor responses showed no evidence of tachyphylaxis, so forearm norepinephrine spillover values after 7 minutes (6.6 +/- 0.94 ng/min), 15 minutes (7.6 +/- 1.5 ng/min), and 4 hours (8.8 +/- 1.1 ng/min) of isoproterenol infusion were increased and similar. Minimal systemic effects were observed, and there was no evidence of tolerance, there being no difference in heart rate after 7 minutes (70.7 +/- 2.7 beats per minute) and 4 hours (72.2 +/- 3.6 beats per minute) of isoproterenol infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary sodium intake modulates vasodilation mediated by nitroprusside but not by methacholine in the human forearm

Studies in animals suggest that nitric oxide production is increased under conditions of salt loading and that this increase protects against the development of salt-induced hypertension. To determine the effect of dietary sodium intake on nitric oxide-mediated vascular responses, we studied seven healthy male volunteers twice 4 weeks apart while they were receiving a diet containing 10 or 250 mmol Na+ per 24 hours. Methacholine (0.25 to 8 micrograms/min) and sodium nitroprusside (0.25 to 8 micrograms/min) were infused intra-arterially in incremental doses, and forearm blood flow was measured. The response of forearm blood flow to sodium nitroprusside was greater when subjects received a high sodium diet than when they received a low sodium diet (F = 7.11, P < .05); however, the response to methacholine was not altered by sodium intake (F = 0.57, P = NS). Plasma renin activity was significantly higher (3.99 versus 1.0 ng angiotensin I/mL per hour) when subjects received a low salt diet (P < .05). Systolic pressure, diastolic pressure, heart rate, and baseline forearm blood flow were not affected by sodium status. We conclude that under conditions of salt loading, vasodilation in response to sodium nitroprusside was enhanced, whereas the response to methacholine was not affected, suggesting a differential effect of sodium intake on endothelium-dependent and endothelium-independent responses after the administration of methacholine and sodium nitroprusside, respectively.

[In vitro synergic lymphocyte stimulation in HIV-1 infected patients using inosine derivatives and radio-detoxified endotoxin]

Restoration of immune functions through promoting cell cycle might delay acquired immunodeficiency syndrome development. Therefore, stimulation of peripheral lymphocytes of human immunodeficiency virus-1 infected patients in successive clinical stages was studied by phytohaemagglutinin and other stimulants. In vitro blastogenesis was quantitated by 3H-thymidine uptake. Stimulation by phytohaemagglutinin decreased in patients with AIDS related complex to 63.1%, with AIDS to 13.6% of control values. Small amount of recombinant interleukin-2 or indomethacin solely not promoting lymphocytes, increased response to phytohaemagglutinin minimally. Alone ineffective methyl-ester and methyl-phosphonate inosine derivatives augmented phytohaemagglutinin-response of controls and patients with AIDS related complex by approx. 1.5-fold, but the effect in the case of AIDS patients was minimal. Radio-detoxified endotoxin alone or in combination with phytohaemagglutinin stimulated lymphocytes of both controls and patients with AIDS related complex slightly. Lymphocyte stimulation of patients with AIDS related complex was augmented in concentration-dependent manner, and by synergic effect it approached phytohaemagglutinin-stimulated blastogenesis of controls. Anergy due to human immunodeficiency virus-1 infection damages synchronisation of secondary messenger systems induced on cell surface receptors, therefore their selective influence by recombinant interleukin-2 or indomethacin is less efficient. Inosine derivatives promote cell cycle by inhibiting cyclic adenosine 3',5'-monophosphate production. In the early stage of virus infection, radio-detoxified endotoxin might bind to receptors of immature T cells and facilitate cell cycle through cyclic guanosine 3',5'-monophosphate stimulation. The clinical trials of radio-detoxified endotoxin (Tolerin) have already been launched.