Highly active antiretroviral therapy results in HIV type 1 suppression in lymph nodes, increased pools of naive T cells, decreased pools of activated T cells, and diminished frequencies of peripheral activated HIV type 1-specific CD8+ T cells

This study examines sequential lymph nodes from 13 drug-naive patients before and after 24 weeks of highly active antiretroviral therapy (HAART). A multipronged approach was used to study changes in HIV-1 RNA in each paired lymph node in relation to tissue architecture and frequency of naive T cells. After 24 weeks, all patients showed significant suppression of plasma viral load and 12 of 13 showed concordant viral suppression in the lymph node (p = 0.001). Using in situ hybridization and quantitative image analysis, we showed that HIV-1 RNA was reduced to below detectable levels (two copies per cell) in follicular dendritic cell (FDC) and mononuclear cell pools. Independent immunohistochemical analysis of lymph node sections revealed that 5 of 13 patients displayed increased FDC networks and 6 of 13 showed no change and all patients showed increases in tissue-resident CD4+ cells. All lymph node biopsies at 24 weeks showed increased proportions of CD4+ and CD8+ cells coexpressing the naive markers CD45RA and CD62L when compared with baseline values. Significant correlations existed between viral load suppression and loss of activated CD8+ T cells after 24 weeks in both lymph node and blood, which was mirrored by significantly lowered frequencies of activated peripheral Gag peptide/MHC tetramer+ CD8+ cells. Overall, these data show that a potent and successful treatment strategy that significantly suppresses and removes FDC-resident HIV-1 results in improvements in lymphoid architecture and by so doing provides the structures available for increased numbers of naive cells to interact with cognate antigen. In addition, our article shows that suppression of HIV-1 replication results in diminished frequencies of peripherally activated antigen-specific CD8+ cells.

Gene therapy for myocardial angiogenesis: has it come of age?

Vasculogenesis and angiogenesis are the processes responsible for the development of the circulatory system during embryonic and adult life. Vasculogenesis occurs during embryogenesis while angiogenesis refers to blood vessel formation from any preexisting vasculature. Postnatal angiogenesis resumes during reproduction, wound healing, and ischemia. Excess blood vessel formation may contribute to initiating and maintaining many diseases such as chronic inflammatory disorders, tumor growth, restenosis, and atherosclerosis. In contrast. insufficient blood vessel formation is responsible for tissue ischemia, as in coronary artery disease. An increasing number of patients with advanced coronary artery disease remain symptomatic despite maximal interventional, surgical or medical treatment. Ideally, they would benefit most from additional arterial blood supply to ischemic areas of myocardium. Therapeutic angiogenesis, the ability to induce the growth of new blood vessels, is one of the most intriguing new frontiers in interventional cardiology for this growing patient group. Several approaches are currently undergoing intensive experimental investigations or have already entered early clinical trials involving either local angiogenic peptide administration or the transfection of angiogenic genes. Gene therapy for therapeutic myocardial angiogenesis is the most promising synthesis of two emerging technologies. In the following article, we will review the fundamental pathophysiological concepts of gene-based angiogenic therapy, the technical approaches and delivery systems, and the results of the first clinical trials. We will also discuss the controversies and unresolved issues of this new revascularization therapy.

Maintenance of large numbers of virus-specific CD8+ T cells in HIV-infected progressors and long-term nonprogressors

The virus-specific CD8+ T cell responses of 21 HIV-infected patients were studied including a unique cohort of long-term nonprogressors with low levels of plasma viral RNA and strong proliferative responses to HIV Ags. HIV-specific CD8+ T cell responses were studied by a combination of standard cytotoxic T cell (CTL) assays, MHC tetramers, and TCR repertoire analysis. The frequencies of CD8+ T cells specific to the majority of HIV gene products were measured by flow cytometric detection of intracellular IFN-gamma in response to HIV-vaccinia recombinant-infected autologous B cells. Very high frequencies (0.8-18.0%) of circulating CD8+ T cells were found to be HIV specific. High frequencies of HIV-specific CD8+ T cells were not limited to long-term nonprogressors with restriction of plasma virus. No correlation was found between the frequency of HIV-specific CD8+ T cells and levels of plasma viremia. In each case, the vast majority of cells (up to 17.2%) responded to gag-pol. Repertoire analysis showed these large numbers of Ag-specific cells were scattered throughout the repertoire and in the majority of cases not contained within large monoclonal expansions. These data demonstrate that high numbers of HIV-specific CD8+ T cells exist even in patients with high-level viremia and progressive disease. Further, they suggest that other qualitative parameters of the CD8+ T cell response may differentiate some patients with very low levels of plasma virus and nonprogressive disease.

p-ethynylphenylalanine: a potent inhibitor of tryptophan hydroxylase

Tryptophan hydroxylase (TPH) is the initial and rate-limiting enzyme in serotonin biosynthesis. The enzyme activity is dependent on molecular oxygen, a tetrahydropterin cosubstrate, and ferrous iron. The present study demonstrates that TPH is inhibited by a novel compound, p-ethynylphenylalanine (pEPA), produced by the Heck reaction of trimethylsilylacetylene with N-tertbutyloxycarbonyl-4-iodo-L-phenylalanine methyl ester. pEPA is a more potent and specific inhibitor of TPH than p-chlorophenylalanine (pCPA). In the present study, pEPA was demonstrated to inhibit competitively and reversibly TPH in vitro (Ki = 32.6 +/- 6.2 microM vs. tryptophan). pEPA displayed little inhibitory activity toward tyrosine hydroxylase (EC 1.14.16.2), the initial and rate-limiting enzyme for catecholamine biosynthesis, and no inhibition of phenylalanine hydroxylase or tyrosinase. In addition, pEPA was a poor ligand for the serotonin transporter and several serotonin receptors. Administration of pEPA (30 mg/kg) to rats produced a 95 +/- 5% decrease in TPH activity in brain homogenates and a concomitant decrease in serotonin and 5-hydroxyindole-3-acetic acid levels (85%) at 24 h after injection. In contrast, pCPA produced a similar effect (87 +/- 5% decrease in TPH activity) only at 10 times the concentration (300 mg/kg). These results suggest that pEPA is a selective, reversible, and potent inhibitor of TPH both in vitro and in vivo. The potential for pEPA to inhibit selectively and reversibly the biosynthesis of serotonin may contribute to the characterization of the role of serotonin in behavioral and physiological activities.

Antiviral CD4 and CD8 T-cell memory: differences in the size of the response and activation requirements

Following acute lymphocytic choriomeningitis virus (LCMV) infection, there is a potent antiviral CD8 T-cell response that eliminates the infection. This initial CD8 T-cell response is followed by a period of memory during which elevated numbers of virus-specific CD8 T cells remain in the mouse. CD4 T cells are also activated after LCMV infection, but relatively less is known about the magnitude and duration of the CD4 response. In this study, we used intracellular staining for interferon-gamma to measure both CD4 and CD8 responses in the same mice at the single cell level. After LCMV infection, there was an increase in the number of activated CD4 T cells and an associated increase in the number of virus-specific CD4 T cells. At the peak of this expansion phase, the frequency of virus-specific CD4 T cells was 1 in 20 (0.5-1.0 x 10(6) per spleen). Like the CD8 response, long-term CD4 memory could be found up to a year after the infection with frequencies of approximately 1 in 260 (0.5-1.5 x 10(5) per spleen). However, the magnitude of virus-specific CD8 T cells was greater than virus-specific CD4 T cells during all phases of the immune response (expansion, death, and memory). At day 8, there were 20- to 35-fold more virus-specific CD8 T cells than CD4 T cells. This initial difference in cell number lasted into the memory phase as there remained a ten- to 20-fold difference in the CD8 and CD4 responses. These results highlight the importance of the expansion phase in determining the size of the memory T-cell pool. In addition to the difference in the magnitude, the activation requirements of CD8 and CD4 T-cell responses were different: CD8 T responses were not affected by blockade of CD40-CD40 ligand interaction whereas CD4 responses were reduced 90%. So while there is long-term memory in both the CD8 and CD4 compartments, the rules regulating the activation of CD8 and CD4 T cells and the overall magnitude of the responses are different.

Persistence of memory CD8 T cells in MHC class I-deficient mice

An understanding of how T cell memory is maintained is crucial for the rational design of vaccines. Memory T cells were shown to persist indefinitely in major histocompatibility complex (MHC) class I-deficient mice and retained the ability to make rapid cytokine responses upon reencounter with antigen. In addition, memory CD8 T cells, unlike naïve cells, divided without MHC-T cell receptor interactions. This "homeostatic" proliferation is likely to be important in maintaining memory T cell numbers in the periphery. Thus, after naïve CD8 T cells differentiate into memory cells, they evolve an MHC class I-independent "life-style" and do not require further stimulation with specific or cross-reactive antigen for their maintenance.

Bis[platinum(II)] and bis[platinum(IV)] complexes with optically active bis(vicinal-1,2-diamines) and their interaction with DNA

Bis[platinum(II)] [Cl2Pt(LL)PtCl2] complexes 2,5 and 8 with chiral non-racemic ligands: 1a-c (LL = (R,R), (S,S) and (R,S) N,N'-bis(3,4-diaminobutyl)hexanediamide); 4a,b (LL = (R,R) and (S,S) N,N'-bis[3,4-bis(diaminobutyl)] urea); 7a-d (LL' = (R,R), (S,S), (R,S) and (S,R) 4,5-diamino-N-(3,4-diaminobutyl) pentanamide) and bis[platinum(IV)] complex 10-13 with ligands 1a,b and 4a,b have been prepared and characterized by IR, 1H, 13C and 195Pt NMR spectra. The interactions of 2a-c, 5a, 5b, 8a-d and 10a with dsDNA were investigated with the goal of examining whether the chirality, the nature of the spacer and the oxidation state have an influence on platinum-DNA binding properties. All the bis[platinum(II)] complexes form with dsDNA intra- and interstrand crosslinks and crosslinks over sticky ends, whereas the bis[platinum(IV)] complex 10a only forms intra- and interstrand crosslinks. The platinum-DNA coordination sites were determined by the T4 DNA polymerase footprinting method. The results show that all investigated bis(platinum) complexes have high preference towards distinct purines. All isomeric bis(amide) 2a-c and mono(amide) 8a-d complexes exhibit nearly the same binding pattern, whereas the ureide complexes 5a and 5b have other coordination sites with higher sequence preference. Interestingly, the ureides 5a and 5b differ in their coordination sites not only in comparison to the bis(amides) 2a-c and mono(amides) 8a-d, but also between each other. The bis[platinum(IV)] complex 10a also differs in coordination sites in comparison to all the bis[platinum(II)] compounds.

Molecular interaction of DNA with bisplatinum(II) complexes having bis(vicinal 1,2-diamines) as ligand

The interaction of novel, tetrafunctional bisplatinum compounds with DNA was investigated. These compounds have bis(vicinal 1,2-diamines) as ligand. The reactions' efficiency, types of cross-links, alterations of the global DNA structure, and sequence selectivity differ significantly from the corresponding features of cisplatin. In particular, they form multiple complexes with dsDNA, which include intrastrand, interstrand and interhelical cross-links and cross-links over sticky ends. The novel compounds are able to untwist but not shorten dsDNA. The reactivity and adduct-forming efficiency of these compounds is, depending on the spacer length, 100-200-fold higher than that of cisplatin. As a consequence, interstrand cross-links are also formed to a higher extent. The chemical stability of the interstrand cross-links against cyanide ions, however, is weaker than that of interstrand cross-links formed by cisplatin, suggesting that each platinum sphere of a bisplatinum compound forms intrastrand cross-links. With dsDNA, they show a preference toward purines, particularly guanines, but they apparently are also coordinated to other nucleobases. Their sequence selectivity toward dsDNA is higher than that of cisplatin. Thus, the novel compounds extend the spectrum of alternative platinum-based compounds with chemical features different from cisplatin.

A biological view of drug abuse

In the USA alone, one in four people report having misused psychoactive drugs at some time and over 11% have an active problem. The combined approaches of molecular biology and psychopharmacology reveal that addictive drugs cause long-term changes in brain function and, as a result, addiction is beginning to be seen as a chronic, relapsing illness. As the underlying cellular changes become clearer, the prospects for developing better pharmacotherapeutic strategies are improving.

The biological, social and clinical bases of drug addiction: commentary and debate

This article summarizes the main discussions at a meeting on the biological, social and clinical bases of drug addiction focused on contemporary topics in drug dependence. Four main domains are surveyed, reflecting the structure of the meeting: psychological and pharmacological factors; neurobiological substrates; risk factors (including a consideration of vulnerability from an environmental and genetic perspective); and clinical treatment. Among the topics discussed were tolerance, sensitization, withdrawal, craving and relapse; mechanisms of reinforcing actions of drugs at the behavioural, cognitive and neural levels; the role of subjective factors in drug dependence; approaches to the behavioural and molecular genetics of drug dependence; the use of functional neuroimaging; pharmaceutical and psychosocial strategies for treatment; epidemiological and sociological aspects of drug dependence. The survey takes into account the considerable disagreements and controversies arising from the discussions, but also reaches a degree of consensus in certain areas.

Developing therapies for Alzheimer's disease

With the greying of the population, many more people will suffer from senile dementia, placing an enormous burden on families and on health provision. Alzheimer's disease, by far the most common form of dementia, is a complex disease, whose causes are still poorly understood despite a recent mushrooming in research. Many drugs are being developed that may provide symptomatic relief or slow down deterioration, but preventive therapies still seem a long way off.

Disseminated acanthamebiasis in patients with AIDS. A report of five cases and a review of the literature

BACKGROUND

Acanthamoeba and Leptomyxida are free-living amebae that cause granulomatous amebic encephalitis, a rare, slowly progressive, fatal neurologic process seen in immunosuppressed hosts. In addition, these organisms produce disseminated cutaneous lesions and involve other organs, particularly in patients with the acquired immunodeficiency syndrome (AIDS).

RESULTS

We report five cases of disseminated acanthamebiasis in patients with AIDS, each with cutaneous manifestations but lacking central nervous system involvement. The medial CD4+ T-cell count was 0.024 x 10(9)/L. Skin lesions included pustules, subcutaneous and deep dermal nodules, and ulcers, most often seen on the extremities and face. Histopathologically, both pustular and vasculitic changes were observed; in all cases, the microscopic identification of organisms was difficult because of the macrophagelike appearance of the microbes in routine sections.

CONCLUSIONS

Skin lesions are the most common reported presentation of infections caused by Acanthamoeba and Leptomyxida organisms in patients with AIDS, a minority of whom have central nervous system manifestations. A high index of suspicion is necessary for both the dermatologist and the dermatopathologist. Prognosis is guarded, but early treatment using a combination of intravenous pentamidine and oral fluconazole, sulfadiazine, and flucytosine may be beneficial.

Three-dimensional reconstructions of the developing forebrain in rat embryos

Using a computerized three-dimensional reconstruction technique with serially sectioned rat embryos, changes in the size and form of the forebrain were studied on Embryonic Days (E) 12 (1 day after closure of the neural tube), E15, E18, and E21 (2 days before birth). During this time, the forebrain changes from a relatively simple tubular structure with thin walls surrounding a large ventricular system to a thick-walled brain with a highly convoluted but reduced ventricular system. On E12, the two components of the forebrain, the telencephalon and the diencephalon, cannot be distinguished. Considering the forebrain as a whole (the embryonic prosencephalon), its volume continually increases between E12 and E21 due to the generation, differentiation, and maturation of neurons and glia. Attention was paid to changes in the sizes of the ventricles, the neuroepithelium and the parenchyma. Volumes of the ventricles and the surrounding neuroepithelium rapidly expanded from E12 to E18 and then decreased by E21, while the volume of the parenchyma continually increased. Differential growth of the telencephalon and that of the diencephalon were compared between E15 and E21. The expansion of the telencephalon was much larger than that of the diencephalon. In the telencephalon, the volumes of the lateral ventricles and the surrounding neuroepithelium increased between E15 and E18 and decreased by E21, while in the diencephalon the volumes of the third ventricle and its surrounding neuroepithelium continually declined between E15 and E21. That observation is compatible with previous work showing that the majority of diencephalic structures develop earlier than those in the telencephalon. It is important to note that volume changes in the ventricles and the neuroepithelium are maintained in "lock-step," suggesting a close relationship between the size of the ventricle and the size of the neuroepithelium.

Evidence that Chlamydia pneumoniae causes pneumonia and bronchitis

An epidemic often provides an opportunity to obtain evidence of the etiologic association of a microorganism with disease. Chlamydia pneumoniae TWAR is a newly recognized organism whose relationship to disease is not completely understood. An outbreak of C. pneumoniae infections from November 1990 to February 1991 was studied in University of Washington students. Twelve TWAR infections were identified serologically in 54 students with acute respiratory disease. The organism was isolated from 7 of the 12 and identified by the polymerase chain reaction (PCR) in 2 that were isolation-negative. The organism was not found in any of the 42 serologically negative patients or in 51 control student patients without respiratory illness cultured in 1991. There was no evidence of infection with Mycoplasma pneumoniae or respiratory viruses in the 12 patients with C. pneumoniae infection. During the 4-month outbreak, there was an increase in total pneumonia cases. These findings provide evidence for an etiologic association of C. pneumoniae with pneumonia and bronchitis.

Effect of calcitonin gene-related peptide on well-developed canine coronary collateral vasculature

This study was performed to examine the effect calcitonin gene-related peptide (CGRP) on blood flow through well-developed coronary collateral vessels. Studies were performed in 9 adult mongrel dogs 4-6 months after embolic occlusion of the left anterior descending coronary artery (LAD) with a hollow intravascular plug to stimulate collateral vessel growth. At the time of study, the LAD was cannulated to determine inter-arterial collateral flow from measurement of retrograde blood flow. Radioactive microspheres were injected during retrograde flow collection to determine continuing tissue flow in the collateral dependent region. CGRP was infused into the left main coronary artery in a dose of 0.2 microgram/kg/min to reach collateral vessels originating from the left coronary system. Retrograde blood flow was 40 +/- 9 ml/min during basal conditions and increased 22 +/- 9% in response to infusion of CGRP (n = 9, p < 0.05). Tissue flow to the collateral-dependent myocardial region did not change in response to CGRP infusion. Isolated rings of epicardial collateral vessels contracted with prostaglandin F2 alpha (PGF2 alpha) underwent relaxation in response to CGRP which was similar in magnitude to that of normal coronary arteries of comparable size. These data demonstrate that CGRP causes vasodilation of well-developed epicardial coronary collateral vessels, resulting in an increase in collateral blood flow.

Endothelial function in well-developed canine coronary collateral vessels

This study examined responses of coronary collateral blood flow to endothelial-dependent vasodilators. Studies were performed in 13 dogs 4-6 mo after embolic occlusion of the left anterior descending coronary artery (LAD). Collateral flow was determined as the sum of retrograde flow from the cannulated LAD, and continuing tissue flow was measured with microspheres administered during the retrograde flow collection. Agonists were introduced into the left main coronary artery to reach collaterals arising from the left coronary arterial system. The endothelial-dependent vasodilators acetylcholine and bradykinin caused 21 +/- 7 and 25 +/- 8% increases of collateral flow, respectively (each P < 0.05). This was not different from the 28 +/- 8% increase in collateral flow produced by nitroglycerin. To determine whether vasodilator prostaglandins contributed to the increased collateral flow, studies were performed after cyclooxygenase blockade with indomethacin (5 mg/kg iv). Indomethacin caused a 30 +/- 9% decrease of retrograde flow during basal conditions but did not blunt the maximum collateral flow rates produced by acetylcholine, bradykinin, or nitroglycerin. These data demonstrate intact endothelial-dependent vasodilator mechanisms in the well-developed coronary collateral circulation.

An outbreak of mud-wrestling-induced pustular dermatitis in college students. Dermatitis palaestrae limosae

OBJECTIVE

To investigate an outbreak of gram-negative folliculitis in relation to a common exposure, mud wrestling, and identify risk factors for dermatitis among those who mud wrestled.

DESIGN

Case-control study.

SETTING

University of Washington, Seattle.

PARTICIPANTS

Two college-residence groups of students.

RESULTS

Cultures from affected students and from mud similar to that used for wrestling yielded Enterobacteriaceae. The odds ratio associated with mud wrestling was 79.5 (95% confidence interval, 13.9 to 895.4). Increased time spent wrestling was associated with increased risk. Skin trauma during wrestling or immersion in the mud increased the risk of infection (odds ratio, 23.1; 95% confidence interval, 1.7 to 1440.4).

CONCLUSIONS

Mud wrestling is one cause of pustular follicular dermatitis. Trauma to the skin may be a necessary cofactor for the development of infection.

Effect of cyclooxygenase blockade on blood flow through well-developed coronary collateral vessels

Collateral vessels that develop after coronary artery occlusion demonstrate perivascular inflammation, subintimal hyperplasia, and endothelial proliferation. This study was performed to test the hypothesis that these abnormalities are associated with evidence for increased production of vasodilator prostaglandins. Eight dogs were studied 4-6 months after occlusion of the anterior descending coronary artery had been performed to stimulate collateral vessel growth. At the time of study, the anterior descending coronary artery was cannulated at the site of occlusion to allow measurement of retrograde blood flow as an index of interarterial collateral flow. Injection of radioactive microspheres during the retrograde flow collection allowed determination of continuing tissue flow in the collateral-dependent zone as an index of intramural microvascular collateral flow. Retrograde and tissue flows were measured before and 20 minutes after 5 mg/kg i.v. indomethacin, a dose that caused 95 +/- 3% inhibition of the coronary vasodilation in response to a 500 micrograms intracoronary bolus of arachidonic acid. Heart rate and mean aortic pressure were not significantly altered by indomethacin, and blood flow to the normally perfused myocardial region was not changed by administration of indomethacin. However, indomethacin caused a 40 +/- 7% decrease in retrograde flow (p less than 0.01), and microvascular collateral flow to the dependent myocardium decreased by 20 +/- 10% (p less than 0.05). These data indicate that, unlike the normal coronary circulation, well-developed coronary collateral vessels are under the tonic influence of vasodilator prostaglandins.