Beta-defensins: linking innate and adaptive immunity through dendritic and T cell CCR6

Defensins contribute to host defense by disrupting the cytoplasmic membrane of microorganisms. This report shows that human beta-defensins are also chemotactic for immature dendritic cells and memory T cells. Human beta-defensin was selectively chemotactic for cells stably transfected to express human CCR6, a chemokine receptor preferentially expressed by immature dendritic cells and memory T cells. The beta-defensin-induced chemotaxis was sensitive to pertussis toxin and inhibited by antibodies to CCR6. The binding of iodinated LARC, the chemokine ligand for CCR6, to CCR6-transfected cells was competitively displaced by beta-defensin. Thus, beta-defensins may promote adaptive immune responses by recruiting dendritic and T cells to the site of microbial invasion through interaction with CCR6.

Observation of Bose-Einstein Condensation in a Dilute Atomic Vapor

A Bose-Einstein condensate was produced in a vapor of rubidium-87 atoms that was confined by magnetic fields and evaporatively cooled. The condensate fraction first appeared near a temperature of 170 nanokelvin and a number density of 2.5 x 10(12) per cubic centimeter and could be preserved for more than 15 seconds. Three primary signatures of Bose-Einstein condensation were seen. (i) On top of a broad thermal velocity distribution, a narrow peak appeared that was centered at zero velocity. (ii) The fraction of the atoms that were in this low-velocity peak increased abruptly as the sample temperature was lowered. (iii) The peak exhibited a nonthermal, anisotropic velocity distribution expected of the minimum-energy quantum state of the magnetic trap in contrast to the isotropic, thermal velocity distribution observed in the broad uncondensed fraction.

Biosynthesis and insecticidal properties of plant cyclotides: the cyclic knotted proteins from Oldenlandia affinis

Several members of the Rubiaceae and Violaceae families produce a series of cyclotides or macrocyclic peptides of 29-31 amino acids with an embedded cystine knot. We aim to understand the mechanism of synthesis of cyclic peptides in plants and have isolated a cDNA clone that encodes the cyclotide kalata B1 as well as three other clones for related cyclotides from the African plant Oldenlandia affinis. The cDNA clones encode prepropeptides with a 20-aa signal sequence, an N-terminal prosequence of 46-68 amino acids and one, two, or three cyclotide domains separated by regions of about 25 aa. The corresponding cyclotides have been isolated from plant material, indicating that the cyclotide domains are excised and cyclized from all four predicted precursor proteins. The exact processing site is likely to lie on the N-terminal side of the strongly conserved GlyLeuPro or SerLeuPro sequence that flanks both sides of the cyclotide domain. Cyclotides have previously been assigned an antimicrobial function; here we describe a potent inhibitory effect on the growth and development of larvae from the Lepidopteran species Helicoverpa punctigera.

Spectrum and mode of action of azithromycin (CP-62,993), a new 15-membered-ring macrolide with improved potency against gram-negative organisms

The macrolide antibiotic azithromycin (CP-62,993; 9-deoxo-9a-methyl-9a-aza-9a-homoerythromycin A; also designated XZ-450 [Pliva Pharmaceuticals, Zagreb, Yugoslavia]) showed a significant improvement in potency against gram-negative organisms compared with erythromycin while retaining the classic erythromycin spectrum. It was up to four times more potent than erythromycin against Haemophilus influenzae and Neisseria gonorrhoeae and twofold more potent against Branhamella catarrhalis, Campylobacter species, and Legionella species. It had activity similar to that of erythromycin against Chlamydia spp. Azithromycin was significantly more potent versus many genera of the family Enterobacteriaceae; its MIC for 90% of strains of Escherichia, Salmonella, Shigella, and Yersinia was less than or equal to 4 micrograms/ml, compared with 16 to 128 micrograms/ml for erythromycin. Azithromycin inhibited the majority of gram-positive organisms at less than or equal to 1 micrograms/ml. It displayed cross-resistance to erythromycin-resistant Staphylococcus and Streptococcus isolates. It had moderate activity against Bacteroides fragilis and was comparable to erythromycin against other anaerobic species. Azithromycin also demonstrated improved bactericidal activity in comparison with erythromycin. The mechanism of action of azithromycin was similar to that of erythromycin since azithromycin competed effectively for [14C]erythromycin ribosomebinding sites.

Association between blood pressure level and the risk of myocardial infarction, stroke, and total mortality: the cardiovascular health study

BACKGROUND

Recent reports have drawn attention to the importance of pulse pressure as a predictor of cardiovascular events. Pulse pressure is used neither by clinicians nor by guidelines to define treatable levels of blood pressure.

METHODS

In the Cardiovascular Health Study, 5888 adults 65 years and older were recruited from 4 US centers. At baseline in 1989-1990, participants underwent an extensive examination, and all subsequent cardiovascular events were ascertained and classified.

RESULTS

At baseline, 1961 men and 2941 women were at risk for an incident myocardial infarction or stroke. During follow-up that averaged 6.7 years, 572 subjects had a coronary event, 385 had a stroke, and 896 died. After adjustment for potential confounders, systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure were directly associated with the risk of incident myocardial infarction and stroke. Only SBP was associated with total mortality. Importantly, SBP was a better predictor of cardiovascular events than DBP or pulse pressure. In the adjusted model for myocardial infarction, a 1-SD change in SBP, DBP, and pulse pressure was associated with hazard ratios (95% confidence intervals) of 1.24 (1.15-1.35), 1.13 (1.04-1.22), and 1.21 (1.12-1.31), respectively; and adding pulse pressure or DBP to the model did not improve the fit. For stroke, the hazard ratios (95% confidence intervals) were 1.34 (1.21-1.47) with SBP, 1.29 (1.17-1.42) with DBP, and 1.21 (1.10-1.34) with pulse pressure. The association between blood pressure level and cardiovascular disease risk was generally linear; specifically, there was no evidence of a J-shaped relationship. In those with treated hypertension, the hazard ratios for the association of SBP with the risks for myocardial infarction and stroke were less pronounced than in those without treated hypertension.

CONCLUSION

In this population-based study of older adults, although all measures of blood pressure were strongly and directly related to the risk of coronary and cerebrovascular events, SBP was the best single predictor of cardiovascular events.

Hypoxic induction of interleukin-8 gene expression in human endothelial cells

Because leukocyte-mediated tissue damage is an important component of the pathologic picture in ischemia/reperfusion, we have sought mechanisms by which PMNs are directed into hypoxic tissue. Incubation of human endothelial cells (ECs) in hypoxia, PO2 approximately 14-18 Torr, led to time-dependent release of IL-8 antigen into the conditioned medium; this was accompanied by increased chemotactic activity for PMNs, blocked by antibody to IL-8. Production of IL-8 by hypoxic ECs occurred concomitantly with both increased levels of IL-8 mRNA, based on polymerase chain reaction analysis, and increased IL-8 transcription, based on nuclear run-on assays. Northern analysis of mRNA from hypoxic ECs also demonstrated increased levels of mRNA for macrophage chemotactic protein-1, another member of the chemokine superfamily of proinflammatory cytokines. IL-8 gene induction was associated with the presence of increased binding activity in nuclear extracts from hypoxic ECs for the NF-kB site. Studies with human umbilical vein segments exposed to hypoxia also demonstrated increased elaboration of IL-8 antigen compared with normoxic controls. In mice exposed to hypoxia (PO2 approximately 30-40 Torr), there was increased pulmonary leukostasis, as evidenced by increased myeloperoxidase activity in tissue homogenates. In parallel, increased levels of transcripts for IP-10, a murine homologue in the chemokine family related to IL-8, were observed in hypoxic lung tissue. Taken together, these data suggest that hypoxia constitutes a stimulus for leukocyte chemotaxis and tissue leukostasis.

Human papillomavirus testing in primary cervical screening

Several studies have examined the role of tests for human papillomavirus (HPV) in screening for cervical cancer but as yet the relevance is unclear. We looked at HPV testing for types 16, 18, 31, and 33 on material taken at the time of a cervical smear in 2009 eligible women having routine screening. Women with any degree of dyskaryosis or high levels of one of these HPV types were referred for colposcopy. 44% of the cervical intraepithelial neoplasia (CIN) lesions of grade 2/3 detected had negative cytology and were found only by HPV testing. A further 22% of the CIN 2/3 lesions were positive for HPV but showed only borderline or mild cytological changes. The positive predictive value of HPV testing was 42%, which was similar to that for moderate dyskaryosis. HPV types 16 and 31 were more sensitive and specific for CIN 2/3 than were types 18 or 33. However, 25% of the CIN 2/3 lesions were not detected by these four HPV tests. We suggest that HPV testing could usefully augment but not replace conventional cytology. These results should stimulate a much larger randomised trial to assess the impact of these improved CIN 2/3 detection rates on the subsequent incidence of invasive cancer.

The subiculum: a review of form, physiology and function

We review the neuroanatomical, neurophysiological and functional properties of the mammalian subiculum in this paper. The subiculum is a pivotal structure positioned between the hippocampus proper and entorhinal and other cortices, as well as a range of subcortical structures. It is an under-investigated region that plays a key role in the mediation of hippocampal-cortical interaction. We argue that on neuroanatomical, physiological and functional grounds, the subiculum is properly part of the hippocampal formation, given its pivotal role in the hippocampal circuit. We suggest that the term "subicular complex" embraces a heterogenous range of distinct structures and this phrase does not connote a functionally or anatomically meaningful grouping of structures. The subiculum has a range of electrophysiological and functional properties which are quite distinct from its input areas; given the widespread set of cortical and subcortical areas with which it interacts, it is able to influence activity in quite disparate brain regions. The rules which govern the plasticity of synaptic transmission are not well-specified; it shares some properties in common with the hippocampus proper, but behaves quite differently in other respects. Equally, its functional properties are not well-understood, it plays an important but ill-defined role both in spatial navigation and in mnemonic processing. The important challenges for the future revolve around the theoretical specification of its unique contribution to hippocampal formation processing on the one hand, and the experimental investigation of the many open questions (anatomical, physiological, pharmacological, functional) regarding its properties, on the other.

Genome-wide mapping with biallelic markers in Arabidopsis thaliana

Single-nucleotide polymorphisms, as well as small insertions and deletions (here referred to collectively as simple nucleotide polymorphisms, or SNPs), comprise the largest set of sequence variants in most organisms. Positional cloning based on SNPs may accelerate the identification of human disease traits and a range of biologically informative mutations. The recent application of high-density oligonucleotide arrays to allele identification has made it feasible to genotype thousands of biallelic SNPs in a single experiment. It has yet to be established, however, whether SNP detection using oligonucleotide arrays can be used to accelerate the mapping of traits in diploid genomes. The cruciferous weed Arabidopsis thaliana is an attractive model system for the construction and use of biallelic SNP maps. Although important biological processes ranging from fertilization and cell fate determination to disease resistance have been modelled in A. thaliana, identifying mutations in this organism has been impeded by the lack of a high-density genetic map consisting of easily genotyped DNA markers. We report here the construction of a biallelic genetic map in A. thaliana with a resolution of 3.5 cM and its use in mapping Eds16, a gene involved in the defence response to the fungal pathogen Erysiphe orontii. Mapping of this trait involved the high-throughput generation of meiotic maps of F2 individuals using high-density oligonucleotide probe array-based genotyping. We developed a software package called InterMap and used it to automatically delimit Eds16 to a 7-cM interval on chromosome 1. These results are the first demonstration of biallelic mapping in diploid genomes and establish means for generalizing SNP-based maps to virtually any genetic organism.

Leptomyxid ameba, a new agent of amebic meningoencephalitis in humans and animals

Amebae belonging to the order Leptomyxida are regarded as innocuous soil organisms incapable of infecting mammals. We report here the isolation of a leptomyxid ameba from the brain of a pregnant baboon (Papio sphinx) that died of meningoencephalitis at the San Diego Zoo Wild Animal Park. By using rabbit anti-leptomyxid serum in the immunofluorescence assay, we have identified the leptomyxid ameba in the brain sections of a number of human encephalitic cases from around the world as well as a few cases of meningoencephalitis in animals in the United States, which suggests that the leptomyxid amebae are potential etiologic agents of fatal meningoencephalitis in humans and animals.

N-acetylcysteine replenishes glutathione in HIV infection

BACKGROUND

Glutathione (GSH) deficiency is common in HIV-infected individuals and is associated with impaired T cell function and impaired survival. N-acetylcysteine (NAC) is used to replenish GSH that has been depleted by acetaminophen overdose. Studies here test oral administration of NAC for safe and effective GSH replenishment in HIV infection.

DESIGN

Oral NAC administration in a randomized, 8-week double-blind, placebo-controlled trial followed by optional open-label drug for up to 24 weeks.

SUBJECTS

HIV-infected, low GSH, CD4 T cells < 500 micro L(-1), no active opportunistic infections or other debilitation; n = 81. Study conducted prior to introduction of protease inhibitors.

RESULTS

Whole blood GSH levels in NAC arm subjects significantly increased from 0.88 mM to 0.98 mM, bringing GSH levels in NAC-treated subjects to 89% of uninfected controls (P = 0.03). Baseline GSH levels in the placebo group (0.91) remained essentially the same during the 8 week placebo-controlled trial. T cell GSH, adjusted for CD4 T cell count and beta2-microglobulin levels, also increased in the NAC-treated subjects (P = 0.04). Adverse effects were minimal and not significantly associated with NAC ingestion.

CONCLUSION

NAC treatment for 8 weeks safely replenishes whole blood GSH and T cell GSH in HIV-infected individuals. Thus, NAC offers useful adjunct therapy to increase protection against oxidative stress, improve immune system function and increase detoxification of acetaminophen and other drugs. These findings suggest that NAC therapy could be valuable in other clinical situations in which GSH deficiency or oxidative stress plays a role in disease pathology, e.g. rheumatoid arthritis, Parkinson's disease, hepatitis, liver cirrhosis, septic shock and diabetes.

Routine quantitative analysis of brain and cerebrospinal fluid spaces with MR imaging

A computerized system for processing spin-echo magnetic resonance (MR) imaging data was implemented to estimate whole brain (gray and white matter) and cerebrospinal fluid volumes and to display three-dimensional surface reconstructions of specified tissue classes. The techniques were evaluated by assessing the radiometric variability of MR volume data and by comparing automated and manual procedures for measuring tissue volumes. Results showed (a) the homogeneity of the MR data and (b) that automated techniques were consistently superior to manual techniques. Both techniques, however, were affected by the complexity of the structure, with simpler structures (eg, the intracranial cavity) showing less variability and better spatial correlation of segmentation results between raters. Moreover, the automated techniques were completed for whole brain in a fraction of the time required to complete the equivalent segmentation manually. Additional evaluations included interrater reliability and an evaluation that included longitudinal measurement, in which one subject was imaged sequentially 24 times, with reliability computed from data collected by three raters over 1 year. Results showed good reliability for the automated segmentation procedures.

Causes of death in racehorses over a 2 year period

Necropsies were performed on 496 horses that had a fatal injury or illness at a California racetrack during the period February 20th 1990 to March 1st 1992. The primary cause of death was categorised by breed, activity at time of injury or illness and organ system affected. Most of the submissions were Thoroughbred horses (432) and Quarter Horses (46). Most of the injuries occurred while racing (42%) and in training sessions (39%); with fewer non-exercise (12%) and accident (7%) related injuries or illnesses. Musculoskeletal injuries accounted for 83% of the Thoroughbred and 80% of the Quarter Horse submissions. The Thoroughbred horses incurred 306 fractures with 263 in the limbs and 90% of those in the forelimbs. The proximal sesamoid bone(s), third metacarpal bone and humerus were the most common bones fractured in Thoroughbred horses and Quarter Horses. Other major causes of death included respiratory, digestive and multi-organ system disorders.

Detection of serum antibody responses in cattle with natural or experimental Neospora infections

Parasite-specific antibody responses were detected using an indirect fluorescent antibody (IFA) test in cattle that were naturally or experimentally infected with Neospora parasites. The test was developed using Neospora tachyzoites isolated from an aborted bovine fetus and grown in bovine cell cultures (isolate BPA1). In all cases, infections were confirmed by the identification of Neospora tachyzoites and/or bradyzoite cysts in fetal or calf tissues using an immunoperoxidase test procedure. Fifty-five naturally infected cows that aborted Neospora-infected fetuses had titers of 320-5,120 at the time of abortion. The titer of 6 cows that were serologically monitored over a prolonged period decreased to 160-640 within 150 days after they aborted infected fetuses. Two of the cows showed an increase in their Neospora titers during their subsequent pregnancy, and they gave birth to congenitally infected calves that had precolostral titers of 10,240-20,480. Postcolostral titers of these calves and of 4 other calves with congenital Neospora infections were all > or = 5,120, whereas calves with no detectable parasites had titers < or = 160. Two pregnant heifers that were experimentally infected with the BPA1 isolate at approximately 120 days gestation seroconverted to Neospora antigens within 9 days and developed peak titers of 5,120 and 20,480 within 32 days of infection. The fetus taken by caesarean section 32 days postinfection from 1 heifer and the full-term calf born to the other had Neospora titers of 640 and 10,240, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Transforming growth factor(s) production enables cells to grow in the absence of serum: an autocrine system

Kirsten murine sarcoma virus (KiMSV)-transformed rat-1, normal rat kidney (NRK), and BALB/c 3T3 cells are capable of continual growth in a serum-free medium supplemented with transferrin and insulin but with no exogenous mitogenic growth factors. Cells transformed by a mutant of KiMSV that is temperature sensitive for the maintenance of transformation grow in this medium at the permissive temperature only. At the nonpermissive temperature, growth is dependent upon the presence of serum-free conditioned medium from the transformed cells. Normal rat-1 cells are also dependent upon factors from the transformed cells for growth in this serum-free/mitogen-free medium. The serum-derived growth factors, epidermal growth factor, and fibroblast growth factor have no effect on the transformed cells, although epidermal growth factor can replace transforming growth factors produced by KiMSV-transformed cells for the growth of rat-1 cells. Growth of the transformed cells in serum-free medium at clonal densities is dependent upon the presence of conditioned medium collected from the same cells grown to high densities. These results show that (i) growth in serum-free/mitogen-free medium is a general property of KiMSV-transformed cells and (ii) growth of the transformed cells in this medium is dependent upon the presence of growth factors known to be produced by the cells, and they provide support for the hypothesis that serum-free growth of KiMSV-transformed cells is dependent upon ectopically produced growth factors.

Responses to single pulse electrical stimulation identify epileptogenesis in the human brain in vivo

The aim of the present study was to investigate in vivo cortical excitability in the human brain. We studied 45 consecutive patients with refractory epilepsy in whom subdural or intracerebral electrodes were implanted for assessment prior to epilepsy surgery. We compared cortical responses to single pulse stimulation (up to 8 mA, 1 ms duration) in areas where seizure onset occurred, with responses recorded elsewhere. Two main types of responses were seen: (i) 'early responses', spikes and/or slow waves starting within 100 ms after the stimulus which were observed in most regions in all patients; and (ii) 'delayed responses', spikes or sharp waves occurring between 100 ms and 1 s after stimulation which were seen in some regions in 27 patients. The distributions of early and delayed responses were compared with the topography of seizure onset. Whereas early responses were seen in most regions and seem to be a normal response of the cortex to single pulse stimulation, the distributions of delayed responses were significantly associated with the regions where seizure onset occurred. We conclude that the presence of delayed responses can identify regions of hyperexcitable cortex in the human brain. The study of delayed responses may improve our understanding of the physiology and dynamics of neuronal circuits in epileptic tissue and may have an immediate clinical application in assessment of candidates for surgical treatment of epilepsy.

School-associated violent deaths in the United States, 1994-1999

CONTEXT

Despite the public alarm following a series of high-profile school shootings that occurred in the United States during the late 1990s, little is known about the actual incidence and characteristics of school-associated violent deaths.

OBJECTIVE

To describe recent trends and features of school-associated violent deaths in the United States.

DESIGN, SETTING, AND SUBJECTS

Population-based surveillance study of data collected from media databases, state and local agencies, and police and school officials for July 1, 1994, through June 30, 1999. A case was defined as a homicide, suicide, legal intervention, or unintentional firearm-related death of a student or nonstudent in which the fatal injury occurred (1) on the campus of a public or private elementary or secondary school, (2) while the victim was on the way to or from such a school, or (3) while the victim was attending or traveling to or from an official school-sponsored event.

MAIN OUTCOME MEASURES

National estimates of risk of school-associated violent death; national trends in school-associated violent deaths; common features of these events; and potential risk factors for perpetration and victimization.

RESULTS

Between 1994 and 1999, 220 events resulting in 253 deaths were identified; 202 events involved 1 death and 18 involved multiple deaths (median, 2 deaths per multiple-victim event). Of the 220 events, 172 were homicides, 30 were suicides, 11 were homicide-suicides, 5 were legal intervention deaths, and 2 were unintentional firearm-related deaths. Students accounted for 172 (68.0%) of these deaths, resulting in an estimated average annual incidence of 0.068 per 100 000 students. Between 1992 and 1999, the rate of single-victim student homicides decreased significantly (P =.03); however, homicide rates for students killed in multiple-victim events increased (P =.047). Most events occurred around the start of the school day, the lunch period, or the end of the school day. For 120 (54.5%) of the incidents, respondents reported that a note, threat, or other action potentially indicating risk for violence occurred prior to the event. Homicide offenders were more likely than homicide victims to have expressed some form of suicidal behavior prior to the event (odds ratio [OR], 6.96; 95% confidence interval [CI], 1.96-24.65) and been bullied by their peers (OR, 2.57; 95% CI, 1.12-5.92).

CONCLUSIONS

Although school-associated violent deaths remain rare events, they have occurred often enough to allow for the detection of patterns and the identification of potential risk factors. This information may help schools respond to this problem.

Fixation, polyethylene wear, and pelvic osteolysis in primary total hip replacement

A multicenter retrospective review was performed analyzing 1081 primary total hip replacements in 944 patients using the Harris Galante-I cementless acetabular component with screw fixation. All patients were followed up for a minimum of 5 years with a mean followup of 81 months. Linear polyethylene wear averaged 0.11 mm/year (range, 0-0.86 mm/year). Pelvic osteolysis was seen in 25 patients (2.3%). Migration of the acetabular component was seen in four hips. A subgroup of patients was reanalyzed at a minimum followup of 10 years. The mean linear polyethylene wear rate remained 0.11 mm/year. In this group, only one socket had migrated. There was an association between wear rate and age. On average, younger patients had higher wear rates. The risk for having pelvic osteolysis develop and the need for revision surgery also was age-related. Twenty-two percent of hip replacements (15 hips) in patients younger than 50 years of age at the time of their index operation had pelvic osteolysis develop. In contrast, for patients older than 50 years of age at the time of surgery only 7.8% (eight hips) had osteolysis of the pelvis develop. For patients older than 70 years of age at the time of primary total hip replacement, none had pelvic osteolysis develop.

Type-specific human papillomavirus DNA in abnormal smears as a predictor of high-grade cervical intraepithelial neoplasia

Human papillomavirus (HPV) typing and quantitation by polymerase chain reaction was performed on exfoliated cells from 133 women referred for colposcopy because of an abnormal smear. High levels of HPV 16 correctly predicted cervical intraepithelial neoplasia (CIN) grade II-III in 93% of its occurrences, but only 59% of cases of CIN III were associated with high levels of this type. Eighty-four per cent of CIN III lesions contained high levels of at least one of HPV types 16, 18, 31, 33 and 35, but the other types were less specific for CIN III than HPV 16. Overall HPV testing compared favourably with cytology for predicting high-grade CIN lesions, but it would appear that some combination of the two modalities will produce better performance than either alone. In particular, HPV testing appears to be helpful in determining which women with mildly abnormal smears have high-grade underlying lesions in need of immediate referral for colposcopy.

Canine distemper epizootic in lions, tigers, and leopards in North America

Canine distemper virus (CDV) infection occurred in captive leopards (Panthera pardus), tigers (Panthera tigris), lions (Panthera leo), and a jaguar (Panthera onca) in 1991 and 1992. An epizootic affected all 4 types of cats at the Wildlife Waystation, San Fernando, California, with 17 mortalities. CDV-infected raccoons were thought to be the source of infection in these cats. Two black leopards died at the Naibi Zoo, Coal Valley, Illinois, and 2 tigers died at the Shambala Preserve, Acton, California. Initial clinical signs were anorexia with gastrointestinal and/or respiratory disease followed by seizures. Canine distemper virus was isolated from 3 leopards, 3 tigers, and 3 lions that died or were euthanized when moribund. Monoclonal antibody testing identified the virus isolates as CDV. Gross and histopathologic findings were similar to those found in canids with distemper with a few exceptions. There were fewer lesions in the brain, and there was a pronounced type 2 cell proliferation in the lung, with inclusion bodies and CDV antigen demonstrated by immunohistology. Neutralizing antibody to CDV was found in high titers in serum from most animals but was absent or was found only in low titers in some cats that succumbed after CDV infection. There was a marked difference in neutralizing antibody titers when tests were done with different strains of CDV.

Effects of vitrified and nonvitrified sugars on phosphatidylcholine fluid-to-gel phase transitions

DSC was used to study the ability of glass-forming sugars to affect the gel-to-fluid phase transition temperature, T(m), of several phosphatidylcholines during dehydration. In the absence of sugars, T(m) increased as the lipid dried. Sugars diminished this increase, an effect we explain using the osmotic and volumetric properties of sugars. Sugars vitrifying around fluid phase lipids lowered T(m) below the transition temperature of the fully hydrated lipid, T(o). The extent to which T(m) was lowered below T(o) ranged from 12 degrees to 57 degrees, depending on the lipids' acyl chain composition. Sugars vitrifying around gel phase lipids raised T(m) during the first heating scan in the calorimeter, then lowered it below T(o) in subsequent scans of the sample. Ultrasound measurements of the mechanical properties of a typical sugar-glass indicate that it is sufficiently rigid to hinder the lipid gel-to-fluid transition. The effects of vitrification on T(m) are explained using the two-dimensional Clausius-Clapeyron equation to model the mechanical stress in the lipid bilayer imposed by the glassy matrix. Dextran and polyvinylpyrrolidone (PVP) also vitrified but did not depress T(m) during drying. Hydration data suggest that the large molecular volumes of these polymers caused their exclusion from the interbilayer space during drying.

Derivation of neurotropic simian immunodeficiency virus from exclusively lymphocytetropic parental virus: pathogenesis of infection in macaques

Neurological disease resulting from lentivirus (including human immunodeficiency virus) infections is usually caused by a strain of virus that replicates productively in microglia in vivo and in macrophage cultures in vitro. We undertook this study using the model of simian immunodeficiency virus in macaques (SIVmac) to test the hypothesis that macrophage tropism is a prerequisite for neurotropism of the virus. Using molecularly cloned SIVmac239, a virus which is lymphocyte- but not macrophagetropic, we showed that this virus failed to infect brain after intracerebral (i.c.) inoculation into two macaques. Rather, these inoculations resulted in disseminated infection in lymphoid organs and the bone marrow. Two sequential passages of infected bone marrow cells inoculated i.c. into new macaques resulted in severe neurological disease and classical neuropathological lesions. Virus obtained from affected brain answered the hypothetical question: it was neurotropic and macrophagetropic. New findings in the study were that both lymphocyte- and macrophage-tropic viruses were present in the animals, but the viruses localized in different tissues: the lymphotropic virus in the spleen, lymph nodes, and plasma and the macrophagetropic virus in the brain and lungs. To determine whether the brain virus was preferentially neurotropic and whether it had neuroinvasive properties, infectious brain homogenate was inoculated into one animal i.c. and into two others peripherally. The i.c. inoculated animal developed fatal encephalitis 5 months later, and examination of tissues showed cell-free virus only in brain homogenates. Only microglia were infected despite persistent viremia and infection in bone marrow cells. The two macaques inoculated peripherally remained healthy and were euthanized at 6 months. Virus replication was detected only in the bone marrow cells and peripheral blood mononuclear cells. No infection in any macrophage population in visceral organs was detected, and the virus did not invade the brain. The strictly microglial specificity of this virus suggested that different macrophage populations in the body may select specific phenotypes of lentivirus from the quasispecies of virus in the bone marrow. This could provide the basis for specific disease affecting different organ systems.

Preliminary evidence of improved verbal working memory performance and normalization of task-related frontal lobe activation in schizophrenia following cognitive exercises

OBJECTIVE

The authors' goal was to evaluate the possibility of treating brain and behavioral aspects of verbal memory dysfunction in patients with schizophrenia through cognitive exercises.

METHOD

Eight patients did daily verbal memory exercises that became progressively more difficult over a 10-week training period. Memory performance and regional brain activations during a verbal memory task were assessed before and after these exercises.

RESULTS

Verbal but not nonverbal memory performance improved after training; three patients made substantial gains, and five showed little change. Performance gains were correlated with increases in task-related activation of the left inferior frontal cortex. One patient given 5 extra weeks of training 6 weeks after the initial training period showed maintenance of initial performance gains 6 weeks after training, further improvement after the second period of training, and normalization of task-related activation of the left inferior frontal cortex.

CONCLUSIONS

Verbal memory deficits can be ameliorated by memory exercises in some patients with schizophrenia. Performance improvements are associated with increased task-related activation of the same brain region that is activated during verbal memory tasks in healthy individuals.

Human papillomavirus type 16 in cervical smears as predictor of high-grade cervical intraepithelial neoplasia [corrected]

The management of women with mild to moderately dyskaryotic cervical smears would benefit from a non-invasive test that predicts which women have high-grade cervical intraepithelial neoplasia. Detection of human papillomavirus type 16 (HPV16) DNA in cervical smears may be such a test. With the polymerase chain reaction (PCR), we estimated the amount of HPV16 DNA in cervical smears from 85 women referred for colposcopy because of abnormal cytology. An intermediate or high amount of HPV16 DNA predicted the presence of high-grade cervical intraepithelial neoplasia in a subsequent biopsy in almost 90% of patients irrespective of the cytological grade of the referral smear. This technique may allow early identification of those women with low-grade cytological abnormalities who have high-grade underlying cervical disease.