Staining intensity of individual osteons correlated with elastic properties and degrees of mineralization

Surface staining is widely used for histological studies involving undecalcified thick bone sections. Individual osteons, particularly newly formed ones stained with toluidine blue (TB), show various color intensities. We studied the correlations between TB color intensity and the differences in stiffness and degree of mineralization of individual osteons in undecalcified histological sections of goat tibial diaphysis, measured by scanning acoustic microscopy (SAM) and contact microradiography (CMR), respectively. Results showed that all three measurements correlated significantly with each other (r = 0.567 - 0.786; all P < or = 0.01). The TB surface staining intensity of individual osteons correlated better with the reflection coefficient (stiffness index) measured by SAM (r = 0.713) than with the aluminum step-wedge equivalent thickness measured on CMR micrographs (r = 0.567). The aluminum step-wedge equivalent thickness of individual osteons on CMR correlated slightly better with the SAM reflection coefficient (r = 0.786) than with the TB surface staining intensity (r = 0.713). The results of this study suggest that TB surface staining may be used as a simple method for indicating differences in stiffness and degree of mineralization in individual osteons in comparative histological studies.

Asthmatic subjects symptomatically worse at work: prevalence and characterization among a general asthma clinic population

STUDY OBJECTIVES

To assess the prevalence of a historical occupational component to asthma in an adult asthma clinic and to compare characteristics of asthmatic subjects with and without work-attributed symptoms.

DESIGN

A retrospective review of data obtained from a physician-administered questionnaire, answers to which were obtained at the initial patient visit of asthmatic subjects, and which included specific questions regarding the relationship of work to symptoms. Chart review data were used to supplement information on workplace exposures and investigations.

SETTING

A university-based secondary- and tertiary-referral asthma clinic.

PATIENTS

Seven hundred thirty-one adult asthmatic subjects who were referred for assessment and management of asthma.

INTERVENTIONS

Statistical analyses of asthmatic subjects with and without work-attributed symptoms and a determination, from chart review, of the likelihood of causes for symptomatic worsening of asthma at work.

MEASUREMENTS AND RESULTS

Sixty percent of the patients (435) had adult onset of asthma, among whom 310 patients (71%) were employed at the time of their visit. Fifty-one patients reported their asthma to be worse at work (ie, 16% of adult-onset working asthmatic subjects). Sixteen of these patients (31%) had likely or possible sensitizer-induced occupational asthma (OA), and 49% likely had aggravation of underlying asthma. The other 20% of patients had possible OA or aggravation of underlying asthma at work.

CONCLUSIONS

Adult-onset asthmatic subjects commonly report a worsening of asthma at work, more commonly on the basis of likely aggravation of underlying asthma than on the basis of likely or possible OA.

Lack of functional receptors is the only barrier that prevents caprine arthritis-encephalitis virus from infecting human cells

Barriers to replication of viruses in potential host cells may occur at several levels. Lack of suitable and functional receptors on the host cell surface, thereby precluding entry of the virus, is a frequent reason for noninfectivity, as long as no alternative way of entry (e.g., pinocytosis, antibody-dependent adsorption) can be exploited by the virus. Other barriers can intervene at later stages of the virus life cycle, with restrictions on transcription of the viral genome, incorrect translation and posttranslational processing of viral proteins, inefficient viral assembly, and release or efficient early induction of apoptosis in the infected cell. The data we present here demonstrate that replication of caprine arthritis-encephalitis virus (CAEV) is restricted in a variety of human cell lines and primary tissue cultures. This barrier was efficiently overcome by transfection of a novel infectious complete-proviral CAEV construct into the same cells. The successful infection of human cells with a vesicular stomatitis virus (VSV) G-pseudotyped Env-defective CAEV confirmed that viral entry is the major obstacle to CAEV infection of human cells. The fully efficient productive infection obtained with the VSV-G-protein-pseudotyped infectious CAEV strengthened the evidence that lack of viral entry is the only practical barrier to CAEV replication in human cells. The virus thus produced retained its original host cell specificity and acquired no propensity to propagate further in human cultures.

Variation of measured sound speeds in gaseous and liquid air with temperature and pressure

Based on sound speeds in gaseous and liquid air measured by Younglove and Frederick [Int. J. Thermophys. 13(6), 1033-1041 (1992)], empirical equations for the computation of sound speeds in the above media at relatively smaller temperature and pressure ranges were derived. For gaseous air, over a temperature range from 200 to 300 K and pressure from 0.614 to 10.292 MPa, the maximum deviation between the measured sound speeds and those computed with the empirical equation is 56 ppm. For liquid air, over the ranges from 90 to 110 K for temperature and from 0.763 to 13.823 MPa for pressure, the corresponding deviation is 173 ppm.

Pattern formation and selection in quasistatic fracture

Fracture in quasistatically driven systems is studied by means of a discrete spring-block model. Developed from close comparison with desiccation experiments, it describes crack formation induced by friction on a substrate. The model produces cellular, hierarchical patterns of cracks, characterized by a mean fragment size linear in the layer thickness, in agreement with experiments. The selection of a stationary fragment size is explained by exploiting the correlations prior to cracking. A scaling behavior associated with the thickness and substrate coupling, derived and confirmed by simulations, suggests why patterns have similar morphology despite their disparity in scales.

Restricted expression of an adenoviral vector encoding Fas ligand (CD95L) enhances safety for cancer gene therapy

Gene transfer of Fas ligand (CD95L) using adenoviral vectors has been shown to generate apoptotic responses and potent inflammatory reactions that can be used to induce the regression of malignancies in vivo, but these vectors also cause significant hepatotoxicity that may limit their clinical utility. Here we describe an adenoviral vector encoding CD95L with restricted gene expression that reduces its toxicity in vivo. Preclinical efficacy and gene expression studies of lineage-restricted CD95L adenoviral vectors were performed. To enhance its cytotoxicity and reduce potential systemic effects, a noncleavable CD95L was made by deleting a segment containing the cleavage site (CD95L deltaQP). Higher CD95L expression of this mutant was observed on the tumor cell surface, together with a reduction in the release of soluble CD95L. This CD95L cleavage mutant was then expressed under control of a smooth muscle-specific promoter, SM22apha, and analyzed for its ability to suppress the growth of tumors of smooth muscle origin in vivo. Growth of human leiomyosarcomas but not gliomas was inhibited after ADV gene transfer into tumor-bearing immunodeficient mice. In contrast to viral promoters, in which mortality was uniformly seen after injection of 10(12) particles, no significant hepatic injury or systemic toxicity was observed in mice, and the maximum tolerated dose was increased > or = 10- to 100-fold. These findings suggest that restricted specificity of adenoviral CD95L gene expression enhances the safety of this approach for cancer gene therapy.

Viability of competing field theories for the driven lattice gas

It has recently been suggested that the driven lattice gas should be described by an alternate field theory in the limit of infinite drive. We review the original and the alternate field theory, invoking several well-documented key features of the microscopics. Since the alternate field theory fails to reproduce these characteristics, we argue that it cannot serve as a viable description of the driven lattice gas. Recent results, for the critical exponents associated with this theory, are reanalyzed and shown to be incorrect.

Parent management training in a Chinese population: application and outcome

OBJECTIVE

To examine the applicability and outcome of parent management training in a group of Chinese children referred for aggressive and defiant behaviors.

METHOD

Twenty-five children (aged 4-10 years) were assigned to a standardized 8 to 12 sessions of parent management training. Trained child and adolescent psychiatric nurses conducted the treatment. Measures taken at pretreatment, posttreatment, and 4-month follow-up period included the Child Behavior Checklist, direct observation of parent-child interactions, and a parent perception inventory.

RESULTS

Significant therapeutic gains occurred in parent-child interactions, externalizing behaviors, and parents' perception of their parenting behaviors. These were maintained at 4-month follow-up. Fifty-two percent of cases improved to a level below clinical cutoffs. Poor parent-child interactions had stronger correlation with externalizing disturbances than internalizing disturbances. The changes in parent-child interactions had low correlation with the changes in the symptom profiles.

CONCLUSIONS

The data provide preliminary evidence for the efficacy of parent management training for Chinese children with conduct problems. The rationale for its success and modifications to improve its cultural sensitivity are discussed.

Derivation and biological characterization of a molecular clone of SHIV(KU-2) that causes AIDS, neurological disease, and renal disease in rhesus macaques

Previously, we described the derivation of a pathogenic strain of simian-human immunodeficiency virus (SHIV(KU-2)) consisting of the tat, rev, vpu, and env genes of HIV-1 (strain HXB2) in a genetic background of SIV(mac)239 that causes AIDS and productive infection of the CNS in rhesus macaques (Macca mulatta) (Raghavan et al., 1997, Brain Pathol. 7, 851-861). We report here on the characterization of a molecular clone of SHIV(KU-2), designated SHIV(KU-2MC4), that caused CD4(+) T cell loss as well as neurological and renal disease in macaques. DNA sequence analysis of selected SIV regions of SHIV(KU-2MC4) revealed 10 nucleotide changes in the LTR, whereas Gag, Vif, Vpr, Vpx, and Nef had 1, 1, 1, 2, and 13 predicted amino acid substitutions, respectively, compared to SIV(mac)239. DNA sequence analysis of HIV-1 derived regions of SHIV(KU-2MC4) revealed 2, 1, 2, and 18 predicted amino acid substitutions in the Tat, Rev, Vpu, and Env proteins, respectively, when compared to SHIV-4. Unlike the parental SHIV-4, which is not tropic for macrophages, SHIV(KU-2MC4) replicated efficiently in macrophage cultures as determined by p27 assays. However, despite the numerous changes in the Env protein and newly acquired tropism for macrophages, SHIV(KU-2MC4), like the parental SHIV-4, used CXCR4 exclusively as its coreceptor for entry into susceptible cells. Inoculation of SHIV(KU-2MC4) into two rhesus macaques resulted in severe infection in which the numbers of circulating CD4(+) T cells in the blood declined rapidly by 2 weeks postinoculation and virus producing cells in the peripheral blood mononuclear cells were identified throughout the course of infection. At the time of euthanasia (20 and 22 weeks), both macaques had lost a significant amount of weight and had no circulating CD4(+) T cells. In addition, one macaque developed intension tremors and uncoordinated movements. Virological examination of tissues at necropsy revealed active virus replication in both lymphoid and nonlymphoid tissues such as the lung and brain. Histological examination revealed that the induced immunodeficiency was associated with lymphoid depletion of the lymph nodes and spleen, opportunistic infections, lentiviral encephalitis, and severe glomerulosclerosis of the kidney. This molecular clone will serve as the basis for analyzing the molecular determinants through which SHIV(KU-2) causes severe CD4(+) T cell loss, neurological disease, and SHIV nephropathy in rhesus macaques.

Thiazole-derived potent, highly bioavailable short duration growth hormone secretagogues

Replacement of the phenyl in 3 with a 2-pyridyl or 4-thiazolyl group resulted in increased potency in the rat pituitary cell GH release assay and in beagles.

Applications of the green fluorescent protein as a molecular marker in environmental microorganisms

In this review, we examine numerous applications of the green fluorescent protein (GFP) marker gene in environmental microbiology research. The GFP and its variants are reviewed and applications in plant-microbe interactions, biofilms, biodegradation, bacterial-protozoan interactions, gene transfer, and biosensors are discussed. Methods for detecting GFP-marked cells are also examined. The GFP is a useful marker in environmental microorganisms, allowing new research that will increase our understanding of microorganisms in the environment.

Identification of a fimbriae-associated haemagglutinin from Prevotella intermedia

Prevotella intermedia, a putative periodontopathic microorganism, possesses various types of fimbriae (surface appendages). Some of these surface structures mediate the adherence of the organism to several mammalian erythrocytes, resulting in the agglutination of the erythrocytes. Prevotella intermedia fimbriae were solubilized and separated by preparative SDS gel electrophoresis followed by preparative isoelectric focusing to determine which fimbrial component(s) were responsible for the haemagglutinating activity exhibited by these bacteria. Heat treatment of isolated fractions which exhibited haemagglutinating activity revealed the presence of two types of haemagglutinating activity which were either heat sensitive or resistant. Analysis of isolated fractions, which exhibited haemagglutinating activity that were heat labile, by Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of a 3.8 kD peptide. The purified peptide had a pI of 4.8-5.0. Examination of fractions containing this peptide by electron microscopy showed the presence of fimbriae. Immunogold labelling showed that mouse antibodies raised against the 3.8 kD peptide bound specifically and extensively to P. intermedia fimbriae. It appears that this peptide is a fimbriae-associated haemagglutinin and may represent a major constituent of the fimbriae. Further, fractions exhibiting haemagglutinating activity that were heat resistant, which were recovered at a pH of 3.5 in preparative isoelectric focusing of fimbrial samples, did not possess any detectable major protein bands as shown by analytical gel electrophoresis. However, silver stained gels for the detection of lipopolysaccharide (LPS) revealed the presence of LPS-like components in these fractions. In addition, LPS isolated from whole cells showed a similar electrophoretic pattern and exhibited the haemagglutinating activity that was heat resistant. The results of this study strongly suggest that P. intermedia possesses the machinery to agglutinate erythrocytes, which may be a contributing factor in its colonization in vivo.

bcl-1 gene rearrangements in mantle cell lymphoma: a comprehensive analysis of 118 cases, including B-5-fixed tissue, by polymerase chain reaction and Southern transfer analysis

We evaluated 118 cases of mantle cell lymphoma by polymerase chain reaction (PCR) for the major translocation cluster (MTC) region and another breakpoint corresponding to probe p94PS, located 24 kb telomeric to the MTC locus on chromosome 11. The specimens included 64 frozen, 19 formalin-fixed, and 9 B-5-fixed lymph nodes and 26 B-5-fixed bone marrow biopsy specimens. We also analyzed DNA from the 64 frozen lymph nodes by Southern transfer analysis (SB) using three separate bcl-1 breakpoint probes. Gene rearrangements were identified in 17 (PCR) and 18 (SB) of 64 frozen lymph nodes and by PCR in 6 of 19 formalin-fixed lymph nodes, 3 of 9 B-5-fixed lymph nodes, and 12 of 26 B-5-fixed bone marrow cores with MTC locus primers and probe. Only one case showed rearrangement with the p11EH probe that corresponds to breakpoints situated 63 kb telomeric to the MTC locus. No rearrangements were detected by PCR or SB for the breakpoint site corresponding to the p94PS probe, but we identified a polymorphic restriction site with HinD III digest in approximately 25% of the cases. In agreement with other studies, these results confirmed that breakpoints in the MTC region of the bcl-1 locus are tightly clustered and associated with 30 to 40% of mantle cell lymphomas. Other breakpoints in the bcl-1 locus seem to be heterogeneous and cannot be detected by PCR or SB with use of existing probes or primer sequences. The most important finding of our study is optimization of the methodology for the detection of immunoglobulin heavy chain gene rearrangement and MTC region breakpoints by PCR from the DNA isolated from B-5-fixed, paraffin-embedded lymph nodes and bone marrow biopsy specimens. The results obtained from these tissues are comparable to those obtained from frozen or formalin-fixed tissue.

Chronology of genetic changes in the vpu, env, and Nef genes of chimeric simian-human immunodeficiency virus (strain HXB2) during acquisition of virulence for pig-tailed macaques

Recently, we developed a highly pathogenic variant of simian-human immunodeficiency virus, SHIV-4 (containing the tat, rev, vpu, and env of the HXB2 strain of HIV-1 in a genetic background of SIVmac239), through a series of four bone marrow-bone marrow passages-first in rhesus monkeys and then in pig-tailed macaques [Joag et al. (1996) J. Virol. 70, 3189-3197]. Inoculation of pig-tailed macaques with this pathogenic virus (SHIVKU-1) causes subtotal elimination of CD4(+) T cells and fatal opportunistic infections, usually within 6 months. Genetic characterization of SHIVKU-1 showed that it has a functional vpu gene (the first codon is ATG vs ACG for the vpu of SHIV-4) and several amino acid substitutions in Env and nef [Stephens et al. (1997) Virology 231, 313-321]. Two pig-tailed macaques, PPc and PQc, were the first to develop a severe loss of CD4(+) T cells and the acquired immune deficiency syndrome and were euthanized at 26 and 105 weeks, respectively. In this report, we analyzed the changes that occurred in the vpu, nef, and env (gp120) genes of the virus used to inoculate macaques PPc and PQc and established the chronology of changes that occurred in these viral genes as these two animals lost their CD4(+) T cells and progressed to develop acquired immune deficiency syndrome. Compared with SHIV-4, the virus used to inoculate macaques PPc and PQc had 0, 3, and 0 consensus amino acid changes in the Vpu, gp120, and Nef, respectively. An analysis of the viral sequences amplified from peripheral blood mononuclear cells samples taken at various times after inoculation of PPc revealed that the vpu had not reverted to an open reading frame (closed vpu, ACG) at 4 weeks after inoculation, but by 16 weeks vpu had reverted to an open reading frame (open vpu, ATG). Macaque PQc, which had a longer course of disease, had a closed vpu at 4 and 16 weeks, but by 28 weeks, both closed and open vpu were detected. From 39 to 105 weeks, only an open vpu was detected. In both macaques, the reversion to an open vpu correlated well with the second phase (major) of CD4(+) T cell loss. An analysis of the nef and env sequences isolated from the same times after inoculation revealed an association between the reversion of vpu to an open reading frame and the accumulation of increased numbers of consensus changes in these two viral proteins. These data suggest that the concomitant reversion of vpu to an open reading frame along with increased substitutions in Nef and gp120 were important genetic changes in the viral genome that were responsible for the increased and highly efficient rate of replication of the virus in CD4(+) T cells and macrophages, which in turn led to elimination of the CD4(+) T cells and profound loss of immunocompetence in the infected animals.

Genetic and biochemical analysis of mutacin 1140, a lantibiotic from Streptococcus mutans

Streptococcus mutans JH1000 and its derivatives were previously shown (J. D. Hillman, K. P. Johnson, and B. I. Yaphe, Infect. Immun. 44:141-144, 1984) to produce a low-molecular-weight, broad-spectrum bacteriocin-like inhibitory substance (BLIS). The thermosensitive vector pTV1-OK harboring Tn917 was used to isolate a BLIS-deficient mutant, DM25, and the mutated gene was recovered by shotgun cloning in Escherichia coli. Sequence analysis of insert DNA adjacent to Tn917 led to the identification of four open reading frames including two (lanA and lanB) which have substantial homology to the Staphylococcus epidermidis structural gene (epiA) and a modifying enzyme gene (epiB) for biosynthesis of the lantibiotic epidermin, respectively. Although the BLIS activity could not be recovered from broth cultures, high yields were obtained from a solid medium consisting of Todd-Hewitt broth containing 0.5% agarose that was stab inoculated with JH1140 (a spontaneous mutant of JH1000 that produces threefold-elevated amounts of activity). Agar could not substitute for agarose. Chloroform extraction of the spent medium produced a fraction which yielded two major bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The faster-migrating band was absent in chloroform extracts of the mutant, DM25. The amino acid sequence of this band was determined by Edman sequencing and mass spectroscopy. The results showed that it is a lantibiotic, which we have named mutacin 1140, and that the sequence corresponded to that deduced from the lanA sequence. We observed a number of similarities of mutacin 1140 to epidermin and an S. mutans lantibiotic, B-Ny266, but it appears to have significant differences in the positions of its thioether bridges. It also has other unique features with regard to its leader sequence and posttranslational modification. A proposed structure for mutacin 1140 is presented.

Simian-human immunodeficiency virus (SHIV) containing the nef/long terminal repeat region of the highly virulent SIVsmmPBj14 causes PBj-like activation of cultured resting peripheral blood mononuclear cells, but the chimera showed No increase in virulence

SIVsmmPBj14 is a highly pathogenic lentivirus which causes acute diarrhea, rash, massive lymphocyte proliferation predominantly in the gastrointestinal tract, and death within 7 to 14 days. In cell culture, the virus has mitogenic effects on resting macaque T lymphocytes. In contrast, SIVmac239 causes AIDS in rhesus macaques, generally within 2 years after inoculation. In a previous study, replacement of amino acid residues 17 and 18 of the Nef protein of SIVmac239 with the corresponding amino acid residues of the Nef protein of SIVsmmPBj14 yielded a PBj-like virus that caused extensive activation of resting T lymphocytes in cultures and acute PBj-like disease when inoculated into pig-tailed macaques. This study suggested that nef played a major role in both processes. In this study, we replaced the nef/long terminal repeat (LTR) region of a nonpathogenic simian-human immunodeficiency virus (SHIV), SHIVPPc, with the corresponding region from SIVsmmPBj14 and examined the biological properties of the resultant virus. Like SIVsmmPBj14, SHIVPPcPBjnef caused massive stimulation of resting peripheral blood mononuclear cells (PBMC), which then produced virus in the absence of extraneous interleukin 2. However, when inoculated into macaques, the virus failed to replicate productively or cause disease. Thus, while these results confirmed that the nef/LTR region of SIVsmmPBj14 played a major role in the activation of resting PBMC, duplication of the cellular activation process in macaques may require a further interaction between nef and the envelope glycoprotein of simian immunodeficiency virus because SHIV, containing the envelope of human immunodeficiency virus type 1, failed to cause activation in vivo.

In vitro and in vivo evaluations of intestinal barriers for the zwitterion L-767,679 and its carboxyl ester prodrug L-775,318. Roles of efflux and metabolism

The barriers to oral delivery of the hydrophilic zwitterion L-767, 679 (I) and its carboxyl ester prodrug L-775,318 (II) were examined. In the Caco-2 cell model, transport of II, but not I, was strongly oriented in the secretory direction. The basal-to-apical transport of II displayed saturable kinetics and was markedly inhibited by verapamil and quinidine, known P-glycoprotein inhibitors. In Caco-2 cells, metabolism of I was not observed, whereas hydrolysis of II was modest (</=20%). In the in situ rat intestinal loop model, verapamil did not affect the absorption of I but significantly increased the absorption of II. I was resistant to intestinal metabolism, whereas II underwent hydrolysis partially in rat lumen but more extensively in rat intestinal tissue and blood. In vitro metabolism studies indicated that verapamil also inhibited the hydrolysis of II in rats. The inhibition was relatively specific for the intestinal and not the luminal esterases. These results suggested that the intestinal absorption of I was limited not by intestinal efflux or metabolism but more likely by the low lipophilicity of I. However, an efflux system, likely mediated by P-glycoprotein, played an important role in limiting the absorption of II. In rats, metabolism served as an additional barrier to the absorption of II. Verapamil increased the intestinal absorption of the prodrug by inhibiting the efflux system in the two models studied, as well as possibly inhibiting metabolism in rats. For the first time, secretory transport was identified as a cause of the failure to increase the absorption of a lipophilic and cationic prodrug developed to overcome the absorption problem.

A potent, orally bioavailable benzazepinone growth hormone secretagogue

The identification of L-739,943 (8b), a potent, orally bioavailable benzolactam growth hormone secretagogue, is obtained from zwitterionic L-692,429 through modification of its amino acid side chain and replacement of the acidic 2'-tetrazole with the neutral and potency enhancing 2'-(N-methylaminocarbonylamino)methyl substituent. L-739,943 is orally active for the release of growth hormone in beagle dogs at doses as low as 0.5 mg/kg. Oral bioavailability in dogs of 8b is 24% at a dose of 2 mg/kg with a mean drug Cmax of 145 +/- 46 ng/mL. L-739,943 represents a significant breakthrough in terms of both potency and oral bioavailability as compared to the prototype benzolactam L-692,429.

Nucleotide substitutions in the long terminal repeat are not required for development of neurovirulence by simian immunodeficiency virus strain mac

The question of whether consensus nucleotide substitutions in the long terminal repeat (LTR) region of simian immunodeficiency virus strain mac (SIVmac) are important for neurovirulence was investigated in this report. Brains and lymph nodes from two macaques that developed AIDS and encephalitis following inoculation with two strains of neurovirulent SIVmac, and from one animal with AIDS but no neurological disease after inoculation with non-neurovirulent SIVmac239 were used. The 5' LTR regions from neurovirulent SIVmacR71/17E and SIVmac7F-Lu were amplified, cloned and sequenced and these sequences were compared to the LTRs amplified from three regions of the respective encephalitic brains and lymph nodes from macaques inoculated with each virus. The SIVmac7F-Lu and SIVmacR71/17E viruses had zero and three consensus substitutions, respectively, in the U3, R and U5 regions of the LTR compared to that of SIVmac239. The only consensus substitution in the LTR-gag region of the genome was a T to C change at position 829 within the tRNA binding site. The sequences amplified from the brain and lymph nodes of the two animals with AIDS and encephalitis were identical. This single common substitution in this region of the virus genome, the T to C substitution at position 829, was also found in the LTRs isolated from the brain and lymphoid organs from the macaque inoculated with SIVmac239. The virtual identity in nucleotide sequences in the LTR of the neurovirulent and non-neurovirulent viruses and in CNS and lymph tissues of animals inoculated with the viruses suggests that the LTR has no effect on the tissue tropisms of the viruses.

Fate and risk evaluation of persistent organic contaminants and related compounds in Victoria Harbour, Hong Kong

The Environment Protection Department of Hong Kong has a monitoring program for persistent organic contaminants in sediments of Victoria Harbour, the main harbour of Hong Kong. A fugacity model has been used, based on this sedimentary data, to estimate inputs to the system (probably from sewage, stormwater and industrial discharges) as well as the fate of the contaminants, particularly in terms of the aqueous and biotic concentrations. The risk of deleterious effects on the natural marine system, as well as on the consumers of seafood from the system, was carried out using the estimated aqueous and biotic concentrations together with accepted environmental quality guidelines. The result of our analysis indicated that the chlorohydrocarbons, PCBs (as Aroclor 1254) total DDT and total HCH pose a significant risk, and probably have caused damage to the marine ecosystem as well as posing a hazard to seafood consumers. Much higher concentrations of the less toxic total alkanes, nonaromatic hydrocarbons, linear alkyl benzenes and the compounds giving a unresolved complex mixture (UCM) cannot be evaluated due to a lack of environmental guidelines and the complexity of these substances. However, it is probable that these substances add adverse effects to those due to the other contaminants.

Neuroinvasion by ovine lentivirus in infected sheep mediated by inflammatory cells associated with experimental allergic encephalomyelitis

Maedi Visna Virus (MVV) is a prototypic lentivirus that causes infection only in cells of macrophage lineage, unlike the primate lentiviruses which infect both CD4+ T lymphocytes and macrophages. In primates, the earliest viral invasion is associated with the ability of the virus to infect and activate T cells which convey virus to the brain. Infected monocytes in blood rarely cause CNS infection in absence of activation of CD4+ T cells. In the face of lack of infection or activation of T cells by MVV in sheep, the question arises, how does MVV gain access to the brain to cause the classical lesions of visna? In previous studies on experimental induction of visna, sheep were inoculated with virus directly in the brain. In this study, we asked whether neuroinvasion by MVV would occur if sheep were inoculated with virus in a non-neural site. Nine sheep were inoculated intratracheally and all developed systemic infection when examined 3 weeks later. At this time, five were injected intramuscularly with brain white matter homogenized in Freund's complete adjuvant to induce EAE. None of the four animals inoculated with virus alone developed CNS infection despite typical lentiviral infection in lungs, lymphoid tissues and blood-borne mononuclear cells. In contrast, all five of the sheep injected with brain homogenate developed infection in the brain. Virus was produced by macrophages associated with the EAE lesions. This study illustrated that both activated T cells specific for antigen in the CNS and infected macrophages are essential for lentivirus neuropathogenesis.

Fetal cardiorespiratory and neurobehavioral response to zidovudine (AZT) in the baboon

OBJECTIVE

To evaluate the effects of intravenous of zidovudine (AZT) at a dose and duration of infusion comparable to that used clinically on parameters reflective of fetal well-being.

METHODS

Thirteen chronically instrumented noninfected baboons were monitored during intravenous infusions of AZT. Fetal cardiorespiratory activity and neurobehavioral function were assessed with 4-48-hour infusion of AZT to ten mothers (0.5-2.1 mg/kg per hour) and three fetuses (2-6 mg/h), which resulted in fetal plasma concentration of AZT of 194-3100 ng/ml.

RESULTS

No significant differences were found in the mean values in control periods, before and after infusion with values during infusion for parameters of fetal heart rate and rate variability (n = 7), breathing activity (n = 8), electroencephalographic activity (n = 8), and behavioral state (N = 7). No correlations were found with drug level.

CONCLUSIONS

The absence of associations between exposure of the fetal baboon to AZT and changes in parameters reflective of fetal condition suggests that comparable exposure of the human fetus during intravenous infusion of drug would not confound clinical monitoring used to assess fetal well-being. These findings supplement conclusions from clinical research in support of U.S. Public Health Service recommendations that intrapartum fetal monitoring be performed as clinically indicated, not specifically because pregnant patients are treated with intravenous AZT.