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Biomedical subjects

A Cunningham

Publications and source records attributed to A Cunningham.

At least 19 recordsLinked to original sources
PubMed2001

Mast cells/basophils in the peripheral blood of allergic individuals who are HIV-1 susceptible due to their surface expression of CD4 and the chemokine receptors CCR3, CCR5, and CXCR4.

A population of metachromatic cells with mast cell (MC) and basophil features was identified recently in the peripheral blood of patients with several allergic disorders. This study now shows that these metachromatic cells express on their surface the high-affinity IgE receptor (FcepsilonRI), CD4, and the chemokine receptors CCR3, CCR5, and CXCR4, but not the T-cell surface protein CD3 and the monocyte/macrophage surface protein CD68. This population of MCs/basophils can be maintained ex vivo for at least 2 weeks, and a comparable population of cells can be generated in vitro from nongranulated hematopoietic CD3(-)/CD4(+)/CD117(-) progenitors. Both populations of MCs/basophils are susceptible to an M-tropic strain of human immunodeficiency virus 1 (HIV-1). Finally, many patients with acquired immunodeficiency syndrome have HIV-1-infected MCs/basophils in their peripheral blood. Although it is well known that HIV-1 can infect CD4(+) T cells and monocytes, this finding is the first example of a human MC or basophil shown to be susceptible to the retrovirus. (Blood. 2001;97:3484-3490)

Acquired Immunodeficiency Syndrome↗
PubMed2000

Enantioselective reduction of prochiral ketones by catecholborane catalysed by chiral group 13 complexes

LiGaH4, in combination with the S,O-chelate 2-hydroxy-2'-mercapto-1,1'-binaphthyl (MTBH2), forms an active catalyst for the asymmetric reduction of prochiral ketones, with catecholborane as the hydride source. Enantioface differentiation is on the basis of the steric requirements of the ketone substituents. Aryl/ n-alkyl ketones are reduced in 90-93% ee and RC(O)Me (e.g. R = iPr, cycloC6H11, tBu) in 60-72% ee. Other borane sources and alternative catalyst structures based on indium do not form enantioselective catalysts.

Journal Article↗
PubMed2000

Serological survey of measles and rubella immunity in Sydney preschool children.

OBJECTIVES: To estimate the prevalence of serological evidence of immunity to measles and rubella in preschool children in central and southern Sydney (NSW, Australia) and the prevalence of immunity in children with either documented or parentally reported immunization. METHODS: Geographical cluster random sampling was used to select children aged between 18 and 60 months to participate in the present study. Standardized interviews obtained information on each child's reported (by parents) immunization status and documentary evidence of immunization was recorded from the Personal Health Record. Venous blood was collected, serum was separated and stored frozen until tested. Measles and rubella antibodies were measured using ELISA, with either immunofluorescence or haemagglutination inhibition being used to clarify equivocal results. The study was conducted from 1992 to 1994 in conjunction with surveys of blood lead concentrations, iron status and micronutrient status. RESULTS: Parents of 726 of 953 children identified between 9 and 60 months of age agreed to participate in the lead, immunization, iron status and micronutrient studies. Sufficient blood for antibody testing was obtained from 580 children, aged 18 to 62 months at the time of collection. Parents reported that 94.7% (95% confidence interval (CI) 92.7-96.5%) of children had received a measles-mumps or measles-mumps-rubella (MMR) immunization. General practitioners administered 72.8% of these immunizations. The prevalence of serological evidence of immunity to measles and rubella was 88.8% (95% CI 86.2-91.4%) and 91.9% (95% CI 89.6-94.2%). respectively. There was documented evidence of measles and rubella immunization for 88.4% (95% CI 85.7-91.2%) and 86.4% (95% CI 83.4-89.3%) of children, respectively. Of children with documented measles immunization, 91.6% (95% CI 89.2-94.0%) had detectable measles antibody. Of children with documented rubella immunization 97.2% (95% CI 95.8-98.6%) had detectable rubella antibody. CONCLUSIONS: Measles and rubella immunization rates in central and southern Sydney are relatively high and most of these immunizations are provided by the private sector. Immunity to rubella in children with documented rubella immunization is at the level that would be expected from seroconversion studies. Immunity to measles in children with documented measles immunization is slightly lower than expected from seroconversion studies, highlighting the need for the second MMR immunization in preschool children, as well as making near universal immunization imperative if this disease is to be eradicated.

Antibodies, Viral↗
PubMed2000

Penicillopepsin-JT2, a recombinant enzyme from Penicillium janthinellum and the contribution of a hydrogen bond in subsite S3 to k(cat).

The nucleotide sequence of the gene (pepA) of a zymogen of an aspartic proteinase from Penicillium janthinellum with a 71% identity in the deduced amino acid sequence to penicillopepsin (which we propose to call penicillopepsin-JT1) has been determined. The gene consists of 60 codons for a putative leader sequence of 20 amino acid residues, a sequence of about 150 nucleotides that probably codes for an activation peptide and a sequence with two introns that codes for the active aspartic proteinase. This gene, inserted into the expression vector pGPT-pyrG1, was expressed in an aspartic proteinase-free strain of Aspergillus niger var. awamori in high yield as a glycosylated form of the active enzyme that we call penicillopepsin-JT2. After removal of the carbohydrate component with endoglycosidase H, its relative molecular mass is between 33,700 and 34,000. Its kinetic properties, especially the rate-enhancing effects of the presence of alanine residues in positions P3 and P2' of substrates, are similar to those of penicillopepsin-JT1, endothiapepsin, rhizopuspepsin, and pig pepsin. Earlier findings suggested that this rate-enhancing effect was due to a hydrogen bond between the -NH- of P3 and the hydrogen bond accepting oxygen of the side chain of the fourth amino acid residue C-terminal to Asp215. Thr219 of penicillopepsin-JT2 was mutated to Ser, Val, Gly, and Ala. Thr219Ser showed an increase in k(cat) when a P3 residue was present in the substrate, which was similar to that of the wild-type, whereas the mutants Thr219Val, Thr219Gly, and Thr219Ala showed no significant increase when a P3 residue was added. The results show that the putative hydrogen bond alone is responsible for the increase. We propose that by locking the -NH- of P3 to the enzyme, the scissile peptide bond between P1 and P1' becomes distorted toward a tetrahedral conformation and becomes more susceptible to nucleophilic attack by the catalytic apparatus without the need of a conformational change in the enzyme.

Amino Acid Sequence↗
PubMed2000

Neonatal herpes prevention: a minor public health problem in some communities.

BACKGROUND: Neonatal herpes is a condition with high morbidity and mortality. The greatest risk occurs when the mother acquires herpes simplex virus (HSV) towards the end of pregnancy. A study from Seattle has suggested that the risk of acquisition of HSV during pregnancy was 3.7%. In Australia, HSV-2 infection is less common in pregnant women than in the United States. Consequently we conducted a study to establish HSV seroprevalence and the rate of HSV seroconversion in this population. METHODS: The study was conducted at Westmead Hospital, Sydney, between June 1995 and April 1998. Women completed a questionnaire covering risk factors for the acquisition of genital herpes. A serum sample during pregnancy and a specimen of cord blood were obtained and tested for antibodies to HSV-2 using a type specific indirect enzyme linked immunosorbent assay (ELISA). Equivocal results were resolved by western blot. A subset of the paired sera was tested for antibodies to HSV-1. The data were analysed using SPSS. RESULTS: 326 of the 2616 (12.5%) women were HSV-2 seropositive. Three women (0.15%) acquired HSV-2 infection during pregnancy. None of the three babies of these mothers developed neonatal herpes. 416 maternal cord pairs were tested for HSV-1 antibodies and 330 (79.3%) were positive. No HSV-1 seroconversions occurred. CONCLUSIONS: In this population, HSV acquisition was uncommon (0.34% per year) and neonatal herpes was rare. A cost effective analysis suggested that type specific serology to screen pregnant women and their partners in low prevalence communities was not cost effective.

Adult↗
PubMed2000

Antibiotic bead production.

We are reporting a practical technique for the production of antibiotic beads for use in combating musculoskeletal infections. The technique utilizes bead molds with tobramycin powder mixed with polymethylmethacrylate on twisted wire strands to produce strands of 25 beads of various sizes. These beads are gas sterilized and available for use "off the shelf" in a manner that is much more efficient than traditional production by hand on the back table in the operating room. Our technique was also utilized at a second institution to demonstrate its efficacy at another site.

Anti-Bacterial Agents↗
PubMed1999

Genomic organization and biological characterization of the novel human CC chemokine DC-CK-1/PARC/MIP-4/SCYA18.

The chemokines are a group of chemotactic molecules that appear to regulate the directed movement of white blood cells in vitro and in vivo and may therefore play important roles in inflammation and immunity. The genes encoding the chemokines are clustered in close physical proximity to each other. A large cluster of human CC chemokine genes resides on chromosome 17. We have used this information in a positional cloning approach to identify novel chemokine genes within this cluster. We constructed a YAC contig encompassing the MIP-1alpha (HGMW-approved symbol SCYA3) gene region and used exon trapping and sequence analysis to isolate novel chemokine genes. Using this approach, a gene encoding a chemokine named MIP-4, based on its homology with MIP-1alpha (49.5% identity at the nucleotide level and 59.6% at the predicted amino acid level), was found. The MIP-4 gene (HGMW-approved symbol SCYA18) consists of three exons spread over 7.1 kb and is separated from the MIP-1alpha gene by 16 kb. The MIP-4 gene encodes a 750-bp mRNA that is expressed in lung and macrophages but not in brain or muscle. The mRNA encodes an 89-amino-acid protein and includes a predicted signal peptide of 21 amino acids. Recombinant or synthetic MIP-4 induced calcium mobilization in naive and activated T lymphocyte subpopulations in vitro. Injection of synthetic MIP-4 into the peritoneal cavity of mice led to the accumulation of both CD4(+) and CD8(+) T lymphocytes, but not monocytes or granulocytes. These observations provide new information concerning the arrangement of the CC chemokine gene cluster on human chromosome 17 and indicate that the MIP-4 gene product is chemotactic in vivo for both CD4(+) and CD8(+) T lymphocytes and may therefore be implicated in both humoral and cell-mediated immunity.

Amino Acid Sequence↗
PubMed1999

New developments in the epidemiology, natural history and management of genital herpes.

The prevalence of genital herpes is increasing in several populations worldwide. Factors that may be contributing to this increase include greater numbers of sexual partners, the high frequency of asymptomatic infections, poor use of safe sexual practices, and possibly the decreased incidence of childhood oral herpes simplex virus infection. Transmission occurs via skin-to-skin or mucous membrane contact during periods of viral shedding when lesions are present but may also occur when the patient is unaware of the lesions or when lesions are not clinically apparent. This has important implications for strategies to prevent transmission of the disease. The introduction of the antiherpes agent, acyclovir, and more recently famciclovir and valacyclovir, facilitates the management of genital herpes. Treatment of first-episode genital herpes reduces the severity and duration of symptoms, time to lesion healing, and cessation of viral shedding. Episodic treatment of recurrences as they occur may be of benefit to some patients. Daily suppressive therapy significantly reduces the frequency of recurrences and asymptomatic viral shedding. Accordingly, patients who experience frequent or severe recurrences, those particularly troubled by their disease, and those who wish to reduce the frequency of asymptomatic infection generally prefer suppressive therapy. The possibility that suppressive therapy may have an impact on transmission of the disease is currently under investigation. Antiviral treatments have important implications for public health and may help reduce the psychological and psychosocial impact of genital herpes on individual patients.

Antiviral Agents↗
PubMed1999

Etiology of acute lower respiratory tract infection in Central Australian Aboriginal children.

BACKGROUND: Aboriginal children in central Australia have attack rates for acute lower respiratory tract infection (ALRI) that are similar to those in developing countries. Although mortality rates are much lower than in developing countries, morbidity is high and ALRI is still the leading cause of hospitalization. However, there are no data on the etiology of ALRI in this population. METHODS: We prospectively studied 322 cases of ALRI in 280 Aboriginal children admitted to the hospital. Blood, urine and nasopharyngeal aspirate samples were examined for evidence of bacterial, viral and chlamydial infection. RESULTS: The combination of blood culture, viral studies and chlamydial serology provided at least 1 etiologic agent in 170 of 322 (52.5%) cases. Assays for pneumolysin immune complex and pneumolysin antibody increased etiologic diagnosis to 219 (68.0%). Blood cultures were positive in 6% but pneumolysin immune complex and pneumolysin antibody studies were positive in one-third of cases. Evidence of viral infection was present in 155 (48%) of cases compared with 12% in controls (P < 001). There were only 7 possible cases and 2 definite cases of Chlamydia trachomatis and 3 cases of Chlamydia pneumoniae. Coinfection was common in these children. CONCLUSION: These findings have implications for both standard treatment protocols and vaccine strategies. The high rate of coinfection may make it difficult to develop simple clinical predictors of bacterial infection. In the setting of a developed country with efficient patient evacuation services, management algorithms that focus on disease severity and need for hospital referral will be most useful to health staff in remote communities. Pneumococcal conjugate vaccines will be required to reduce the high attack rate of pneumococcal disease.

Australia↗
PubMed1999

Identification of type-specific domains within glycoprotein G of herpes simplex virus type 2 (HSV-2) recognized by the majority of patients infected with HSV-2, but not by those infected with HSV-1.

A combination of phage peptide display library mapping and pepscanning, with both murine monoclonal antibodies and a panel of well-characterized human sera, have been used in order to define type-specific epitopes of glycoprotein G of herpes simplex virus type 2 (HSV-2) (gG2). Both techniques revealed an immunodominant region of gG2, centred around amino acids 525-587 of the uncleaved gG2 molecule. A soluble peptide, equivalent to amino acids 551-570, when used as antigen in an ELISA format was recognized by three out of five murine MAbs and by 20/26 (77%) Western blot anti-HSV-2-positive human sera, but by only 1/63 Western blot anti-HSV-2-negative sera (specificity, 98%). The sensitivity of detection of human anti-HSV-2 antibodies was increased to 90% using a peptide derived from this region, presented on a nitrocellulose membrane. This highly antigenic and type-specific domain of gG2 is located at the junction between the 'unique' region of gG2 and its C-terminal end, which has approximately 50% identity with gG1. A second antigenic region of gG2, amino acids 351-427, which lies within the 'unique' part of gG2, was also identified by both techniques employed in this study and is recognized by a proportion of anti-HSV-2-positive sera. These findings demonstrate the feasibility of developing a peptide-based type-specific assay for the detection of anti-HSV-2 antibody in human sera based on type-specific epitopes of gG2 and have implications for the understanding of the three-dimensional topography of gG2.

Amino Acid Sequence↗
PubMed1999

Diminished production of human immunodeficiency virus type 1 in astrocytes results from inefficient translation of gag, env, and nef mRNAs despite efficient expression of Tat and Rev.

Astrocytes infected with human immunodeficiency virus type 1 (HIV-1) produce only minimal quantities of virus. The molecular events that limit acute-phase HIV-1 infection of astrocytes were examined after inducing acute-phase replication by transfection with the pNL4-3 proviral plasmid. The levels of HIV-1 mRNA were similarly high in both astrocytes and HeLa cells, but astrocytes produced approximately 50-fold less supernatant p24 than HeLa cells. We found that diminished HIV-1 production in astrocytes resulted from inefficient translation of gag, env, and nef mRNAs that were efficiently transported to the cytoplasm. Tat- or Rev-dependent reporter constructs showed no defect in Tat or Rev function in astrocytes compared with HeLa cells. HIV-1 mRNAs were correctly spliced, but only Rev and Tat proteins were efficiently translated from their native mRNAs. Pulse-chase labelling and immunoblot experiments revealed no defect in protein processing, but levels of Gag, Env, or Nef protein expressed were dramatically reduced in astrocytes compared to HeLa cells. These results demonstrate that inefficient translation of HIV-1 structural proteins underlies the restricted infection of astrocytes. The efficient expression of functional Tat and Rev by astrocytes may contribute to HIV-1 neuropathogenesis.

5' Untranslated Regions↗
PubMed1999

Persistent CCR5 utilization and enhanced macrophage tropism by primary blood human immunodeficiency virus type 1 isolates from advanced stages of disease and comparison to tissue-derived isolates.

Viral phenotype, tropism, coreceptor usage, and envelope gene diversity were examined in blood isolates collected from 27 individuals at different stages of human immunodeficiency virus type 1 (HIV-1) disease and tissue derived isolates from 10 individuals with AIDS. The majority (89%) of blood and all tissue HIV-1 isolates from all stages of infection were non-syncytium inducing and macrophage (M) tropic. Tropism and productive infection by HIV isolates in both monocytes and monocyte-derived macrophages (MDM) increased in advanced disease (HIV tropism for monocytes, 1 of 6 from categories I and II versus 11 of 21 [P = 0.05] from category IV and II [CD4 < 250]; and high-level replication in MDM, 1 of 6 from categories I and II versus 16 of 21 from categories IV and II [P = 0. 015]). There was a high level of replication of blood and tissue isolates in T lymphocytes without restriction at any stage. Overall, the level of replication in MDM was 5- to 10-fold greater than in monocytes, with restriction in the latter occurring mainly at entry and later stages of replication. Only three blood isolates were identified as syncytium inducing, and all had a dualtropic phenotype. There was a significant increase of HIV envelope gene diversity, as shown by a heteroduplex mobility assay, in advanced disease; this may partly underlie the increase of HIV replication in MDM. Unlike blood isolates (even those from patients with advanced disease), tissue isolates displayed greater similarities (90%) in productive infection between MDM and monocytes. The majority (87%) of all isolates, including those from patients with advanced disease, used CCR5, and only 5 of 37 isolates showed expanded coreceptor usage. These results indicate that in the late stage of disease with increasing viral load and diversity, CCR5 utilization and M-tropism persist in blood and tissue and the replicative ability in macrophages increases. This suggests that these characteristics are advantageous to HIV and are important to disease progression.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Distribution and characterization of the cell types expressing GALR2 mRNA in brain and pituitary gland.

The neuropeptide galanin mediates its activities through G-protein-coupled receptors, and three receptor subtypes have been described with distinctly different patterns of regional tissue expression. GALR1 is predominantly expressed in basal forebrain, hypothalamus, as well as spinal cord. GALR2 has a wider distribution in brain and is also present in the pituitary gland and peripheral tissues. GALR3 has been found to be widely distributed at low abundance. We examined the distribution of GALR2 in rat brain and pituitary by in situ hybridization histochemistry and found it abundant in regions of hippocampus, piriform and entorhinal cortex, basal nucleus of the accessory olfactory tract, amygdala, hypothalamic nuclei, Purkinje cells, and discrete brainstem nuclei. It is also highly expressed in the intermediate and anterior lobes of the pituitary. Using combined in situ hybridization immunohistochemistry we characterized the neurotransmitter and hormonal phenotype of cells expressing GALR2 mRNA in the hypothalamus and pituitary gland. Our findings suggest GALR2 is a receptor mediating important functions of galanin in the hypothalamic-pituitary axis and may also play a role in hippocampal and cerebellar function.

Animals↗
PubMed1998

Domain-specific gene disruption reveals critical regulation of neuregulin signaling by its cytoplasmic tail.

Neuregulins are a multi-isoform family of growth factors that activate members of the erbB family of receptor tyrosine kinases. The membrane-anchored isoforms contain the receptor-activating ligand in their extracellular domain, a single membrane-spanning region, and a long cytoplasmic tail. To evaluate the potential biological role of the intracellular domain of the membrane-anchored neuregulin isoforms, we used a domain-specific gene disruption approach to produce a mouse line in which only the region of the neuregulin gene encoding almost the entire intracellular domain was disrupted. Consistent with previous reports in which all neuregulin isoforms were disrupted, the resulting homozygous neuregulin mutants died at E10.5 of circulatory failure and displayed defects in neural and cardiac development. To further understand these in vivo observations, we evaluated a similarly truncated neuregulin construct after transient expression in COS-7 cells. This cytoplasmic tail-deleted mutant, unlike wild-type neuregulin isoforms, was resistant to proteolytic release of its extracellular-domain ligand, a process required for erbB receptor activation. Thus, proteolytic processing of the membrane-bound neuregulin isoforms involved in cranial ganglia and heart embryogenesis is likely developmentally regulated and is critically controlled by their intracellular domain. This observation indicates that erbB receptor activation by membrane-bound neuregulins most likely involves a unique temporally and spatially regulated "inside-out" signaling process that is critical for processing and release of the extracellular-domain ligand.

Animals↗
PubMed1998

Role of paired basic residues in the expression of active recombinant galactosyltransferases from the bacterial pathogen Neisseria meningitidis.

The lgtB gene encoding a beta-1,4-galactosyltransferase gene and the lgtC gene encoding an alpha-1,4-galactosyltransferase from the bacterial pathogen Neisseria meningitidis were cloned into an expression vector and overexpressed in Escherichia coli. Both genes expressed very well, but problems with C-terminal proteolysis were encountered with both proteins. The lgtC protein was initially isolated from extracts of recombinant E.coli as a truncated species that retained enzymatic activity, and was subsequently shown by mass spectrometry to be 19 residues shorter than the expected protein. A specific set of engineered C-terminal deletions was constructed to investigate their effect on the expression of lgtC. As many as 28 residues could be deleted with little effect on activity, and with the concomitant improvement of the overall expression up to fivefold over the full length protein. The lgtB protein was also proteolysed in extracts of normal E.coli strains into enzymatically inactive fragments lacking 28 or 41 C-terminal residues. This degradation could be prevented by expression in an ompT protease deficient strain of E.coli. The full length lgtB protein was not stable in soluble protein extracts from all recombinant strains, however a stable enzyme preparation could be achieved with the membrane fraction from cells of the ompT deficient strain expressing lgtB. Specific deletions of lgtB were also constructed, and 15 residues could be removed without loss of enzyme activity and also with the concomitant improvement of the overall expression up to twofold over the full length protein. Longer deletions produced protein but activity could not be detected in these recombinant strains. Examination of the glycosyltransferase sequences from a wide range of bacteria showed their C-terminal segments of approximately 50 amino acids frequently contained paired basic residues. Engineering of these segments may therefore be required as a general practice to produce these enzymes for use in the large scale chemi-enzymatic synthesis of carbohydrate-based therapeutics.

Amino Acid Sequence↗
PubMed1998

Outcomes of a high school program to increase fruit and vegetable consumption: Gimme 5--a fresh nutrition concept for students.

This paper describes an intervention to increase high school students' fruit and vegetable consumption. Twelve schools were randomized to intervention or control conditions. The cohort (2,213 students; 56% females, 84% Caucasian) were followed from 9th to 12th grades. Interventions comprised a media campaign, classroom workshops, school meal modification, and parental support. Usual daily servings of fruit/vegetables increased 14% in the intervention compared to the control group (p > 0.001) the first three years. At follow-up, consumption within the control group also increased, resulting in no significant difference between groups. Intervention group knowledge scores and awareness indicators were significantly higher than those of the control group (p < 0.0001). Gimme 5 provided a first model to show that dietary habits of high school students can be influenced by positive media messages relative to that age group, increased exposure to a variety of tasty products, and minimal classroom activity.

Adolescent↗
PubMed1997

Induction of apoptosis and cell cycle arrest by CP-358,774, an inhibitor of epidermal growth factor receptor tyrosine kinase.

The epidermal growth factor receptor (EGFR) is overexpressed in a significant percentage of carcinomas and contributes to the malignant phenotype. CP-358,774 is a directly acting inhibitor of human EGFR tyrosine kinase with an IC50 of 2 nM and reduces EGFR autophosphorylation in intact tumor cells with an IC50 of 20 nM. This inhibition is selective for EGFR tyrosine kinase relative to other tyrosine kinases we have examined, both in assays of isolated kinases and whole cells. At doses of 100 mg/kg, CP-358,774 completely prevents EGF-induced autophosphorylation of EGFR in human HN5 tumors growing as xenografts in athymic mice and of the hepatic EGFR of the treated mice. CP-358,774 inhibits the proliferation of DiFi human colon tumor cells at submicromolar concentrations in cell culture and blocks cell cycle progression at the G1 phase. This inhibitor produces a marked accumulation of retinoblastoma protein in its underphosphorylated form and accumulation of p27KIP1 in DiFi cells, which may contribute to the cell cycle block. Inhibition of the EGFR also triggers apoptosis in these cells as determined by formation of DNA fragments and other criteria. These results indicate that CP-358,774 has potential for the treatment of tumors that are dependent on the EGFR pathway for proliferation or survival.

Adenosine Triphosphate↗