Dissemination and evaluation of AAP/AHA Neonatal Resuscitation Programme in Ireland

We evaluated the need for a structured Neonatal Resuscitation Programme (NRP) by means of a questionnaire sent to 25 Irish maternity hospitals inquiring about staff availability and current teaching structures. Having taught NRP to almost 1000 health care providers, we present a descriptive evaluation of the programme by a sample of 429 NRP participants, exploring their opinions of NRP. Our results show that midwives were responsible for newborn resuscitation at all low risk deliveries. Only 5 units (23%) had a registrar available on-site 24 hours a day, while the remaining units (77%) had to summon additional medical help from outside, in emergency situations occurring outside of normal working hours. Resuscitation equipment was checked by nurses alone (52%), or by a nurse and physician (48%), on a daily (45%), alternate days (41%) or weekly basis (14%). Although 19 units had some form of neonatal resuscitation training available, only 35% of respondents were happy with the current training structures. Almost half of the 429 providers (45%) replied to the survey. Most (85%) indicated that NRP improved their skills and confidence. Two thirds of participants found the lesson on medications the most difficult theory lesson, while 45% found endotracheal intubation the most difficult skills station. Because of the wide geographical distribution of deliveries in this country, we conclude that all perinatal professionals should be trained to perform newborn resuscitation in a coordinated, team-approach manner. NRP provides such training with a high degree of approval from Irish health care providers.

Inducible interleukin 4 (IL-4) production and mRNA expression following exposure of mice to chemical allergens

Previous investigations have indicated that different classes of chemical allergen provoke discrete immune responses in mice characterized by the development of selective cytokine secretion patterns by draining lymph node cells. It was found that, in mice exposed chronically to chemical respiratory allergens, lymph node cells produced high levels of mitogen-inducible interleukin 4 (IL-4), a cytokine necessary for the development of IgE antibody responses. In contrast, exposure of mice to contact allergens resulted in only low levels of IL-4 production. The studies described here were conducted to determine whether differentially induced expression of IL-4 messenger RNA was independent of the need for mitogen stimulation, unlike secretion of IL-4 protein. Mice were exposed to concentrations of trimellitic anhydride (TMA), a respiratory allergen, or to 2,4-dinitrochlorobenzene (DNCB), a contact allergen, under conditions of equivalent immunogenicity and where the former, but not the latter, resulted in significant production of mitogen-inducible IL-4 protein. The steady state levels of IL-4 mRNA in draining lymph nodes were measured by reverse transcription-polymerase chain reaction after a single or repeated daily application of the test chemical to the ears of chronically sensitized mice. Expression of mRNA for IL-4 was evaluated relative to the expression of a housekeeping gene, glyceraldehyde 3-phosphate dehydrogenase. Both chemicals elicited increased steady state levels of IL-4 mRNA by draining lymph node cells compared with vehicle-treated and naive controls. However, using two different treatment protocols, a chronic and an abbreviated chronic protocol and at all times examined, the elevation in IL-4 mRNA steady state levels induced by TMA was greater than that observed with DNCB. These data provide further support for the differential stimulation by contact and respiratory chemical allergens of cytokine secretion patterns in mice and demonstrate that the divergent production of IL-4 in response to these classes of allergen is at least partly transcriptionally regulated.

Prosystemin from potato, black nightshade, and bell pepper: primary structure and biological activity of predicted systemin polypeptides

Prosystemin is the precursor protein of the 18 amino acid wound signal systemin which activates systemic defense in tomato leaves against insect herbivores (McGurl B, Pearce G, Orozco-Cardenas M, Ryan CA, Science 255 (1992) 1570-1573). Here, we report the isolation of cDNA sequences encoding prosystemin from potato (Solanum tuberosum), black nightshade (S. nigrum), and bell pepper (Capsicum annuum), all members of the Solanaceae family, using reverse-transcription polymerase chain reaction (RT-PCR). Pairwise comparisons of the predicted prosystemin proteins from the three species with tomato prosystemin and among each other indicated sequence identities ranging from 73% to 88%. The deduced systemin polypeptides were synthesized and tested for their capacities to induce the synthesis of the defensive proteinase inhibitors in tomato leaves. Potato and pepper systemins were approximately as active as tomato systemin, whereas nightshade systemin was ten-fold less active. The accumulation of proteinase inhibitor mRNA transcripts could be induced in each of these plants by treatment with the homologous systemin. As in the tomato, in potato, black nightshade, and bell pepper plants, prosystemin homologs appear to function as precursors of systemic wound signals.

A novel gene of tomato preferentially expressed in fruit encodes a protein with a Ca2+-dependent lipid-binding domain

A cDNA clone, called CLB1, was isolated from a cDNA library from tomato (Lycopersicon esculentum) and characterized. The CLB1 cDNA contains an open reading frame of 1518 bp, and encodes a putative protein of 506 amino acids with a predicted molecular mass of 54,633 Da. The deduced CLB1 amino acid sequence contains a domain that exhibits from 26% to 37% identity with the Ca2+-dependent lipid-binding domains of cytosolic phospholipase A2, protein kinase C, Rabphilin-3A, and Synaptotagmin 1 of animals. Southern blot analysis indicates that the CLB1 gene belongs to a small gene family in the tomato genome. The CLB1 mRNA is preferentially expressed in fruit tissues.

Proteinase inhibitors I and II from potatoes specifically block UV-induced activator protein-1 activation through a pathway that is independent of extracellular signal-regulated kinases, c-Jun N-terminal kinases, and P38 kinase

Solar UV irradiation is the causal factor for the increasing incidence of human skin carcinomas. The activation of the transcription factor activator protein-1 (AP-1) has been shown to be responsible for the tumor promoter action of UV light in mammalian cells. We demonstrate that proteinase inhibitor I (Inh I) and II (Inh II) from potato tubers, when applied to mouse epidermal JB6 cells, block UV-induced AP-1 activation. The inhibition appears to be specific for UV-induced signal transduction for AP-1 activation, because these inhibitors did not block UV-induced p53 activation nor did they exhibit any significant influence on epidermal growth factor-induced AP-1 transactivation. Furthermore, the inhibition of UV-induced AP-1 activity occurs through a pathway that is independent of extracellular signal-regulated kinases and c-Jun N-terminal kinases as well as P38 kinases. Considering the important role of AP-1 in tumor promotion, it is possible that blocking UV-induced AP-1 activity by Inh I or Inh II may be functionally linked to irradiation-induced cell transformation.

Myelin basic protein kinase activity in tomato leaves is induced systemically by wounding and increases in response to systemin and oligosaccharide elicitors

In response to wounding, a 48-kDa myelin basic protein (MBP) kinase is activated within 2 min, both locally and systemically, in leaves of young tomato plants. The activating signal is able to pass through a steam girdle on the stem, indicating that it moves through the xylem and does not require intact phloem tissue. A 48-kDa MBP kinase is also activated by the 18-amino acid polypeptide systemin, a potent wound signal for the synthesis of systemic wound response proteins (swrps). The kinase activation by systemin is strongly inhibited by a systemin analog having a Thr-17 --> Ala-17 substitution, which is a powerful antagonist of systemin activation of swrp genes. A 48-kDa MBP kinase activity also increases in response to polygalacturonic acid and chitosan but not in response to jasmonic acid or phytodienoic acid. In def1, a mutant tomato line having a defective octadecanoid pathway, the 48-kDa MBP kinase is activated by wounding and systemin as in the wild-type plants. This indicates that MBP kinase functions between the perception of primary signals and the DEF1 gene product. In response to wounding, the MBP kinase is phosphorylated on phosphotyrosine residues, indicating a relationship to the mitogen-activated protein kinase family of protein kinases.

A gene encoding a chloroplast-targeted lipoxygenase in tomato leaves is transiently induced by wounding, systemin, and methyl jasmonate

We investigated the relationship between the expression of lipoxygenase (LOX) genes and the systemin-dependent wound response in tomato (Lycopersicon esculentum) leaves. A polymerase chain reaction-based approach was used to isolate two tomato Lox cDNAs, called TomLoxC and TomLoxD. Both TomLOXC and TomLOXD amino acid sequences possess an N-terminal extension of about 60 residues that were shown by in vitro uptake to function as transit peptides, targeting these proteins into the chloroplast. Within 30 to 50 min following wounding or systemin or methyl jasmonate treatments, the TomLoxD mRNA level increased and reached a maximum between 1 and 2 h. TomLoxC mRNA was not detectable in leaves and was not found following wounding, but it was found in ripening fruits, indicating that the two tomato Lox genes are regulated in different tissues by different processes. The results suggest that the TomLoxD gene is up-regulated in leaves in response to wounding and encodes a chloroplast LOX that may play a role as a component of the octadecanoid defense-signaling pathway.

Menopausal hormone therapy: physician awareness of patient attitudes

BACKGROUND

Physicians need to be aware of their patients' attitudes toward menopause when counseling women regarding hormone therapy, because menopausal attitudes may affect women's satisfaction with their decisions to use or not to use hormone therapy. Our objectives were to assess physician awareness of patient attitudes on issues surrounding the menopause and hormone therapy, and to determine the prevalence and correlates of hormone use.

METHODS

This cross-sectional survey study was conducted in the primary care outpatient practices of an academic medical center. Surveys were simultaneously administered to female patients aged 50 to 70 years (n = 182) and their primary care physicians immediately after clinical encounters. The surveys contained questions from four established (five-point) attitudinal scales (autonomy, desire for information, philosophy of the menopause, barriers to use of hormone therapy), and questions addressing patients' degree of concern about developing various conditions. Physicians were asked to estimate their patients' attitudes.

PATIENTS AND METHODS

Physicians were generally aware of patients' desire for autonomy (3.2 versus 3.2, P = 1.0), but tended to underestimate patients' desire for information (3.7 versus 4.5, P = 0.0001) and patients' perceptions of barriers to using hormone therapy (3.2 versus 3.4, P = 0.0001). They also underestimated the extent to which patients view menopause as a medical problem (3.0 versus 3.2, P = 0.0001). Physicians overestimated patients' general concern about heart disease (scale difference 0.40, P = 0.0001) and breast cancer (difference 0.23, P = 0.02). Physicians were less aware of their patients' attitudes when they were male (versus female), interns/residents (versus faculty/fellows), and less knowledgeable about menopausal hormone therapy (versus more knowledgeable). The significant predictors of hormone use on multivariate analysis were past hysterectomy, urinary incontinence, alcohol intake, and possession of knowledge regarding hormone therapy.

CONCLUSIONS

Physicians incorrectly estimate some aspects of their patients' attitudes regarding menopause and hormone therapy, and certain physician characteristics may be associated with decreased awareness. To optimize hormone therapy counseling, physicians may need to increase their attention to patients' menopausal attitudes.

Sequence variation in the early genes E1E4, E6 and E7 of human papilloma virus type 6

The majority of condylomata acuminata (anogenital warts) are caused by infection with Human Papilloma Virus type 6 (HPV-6). We have sequenced the HPV-6 early genes, E1-E4, E6 and E7 from wart biopsy DNA samples sourced from the UK and USA and derived a consensus sequence for these genes and the proteins they encode. When compared to the prototype HPV-6b sequence, published over 12 years ago, the E1-E4 consensus sequence showed 3/91 (3.3%) amino acid changes, the E6 consensus sequence showed 1/150 (0.7%) changes and the E7 consensus sequence showed 1/98 (1.0%) changes. Since many of the early gene sequences from biopsy material were more similar to the HPV-6a subtype than HPV-6b, this data supports the use of HPV-6a as the HPV-6 prototype.

Decline in the incidence of late diagnosed congenital dislocation of the hip

INTRODUCTION

We reviewed the incidence of early and late diagnosed CDH over a 13 yr period in a single maternity with a well established follow-up program and a stable population base. In March 1991, all newborn infants were nursed in the lateral or supine position, having previously been nursed prone. In addition, a dedicated hip screener was appointed in October 1992. We wished to determine whether these changes could have led to a reduction in late diagnosed CDH.

METHODS

Babies with suspected CDH were seen by a single consultant orthopaedic surgeon within 1 week of birth. Splints were not applied until diagnosis was confirmed by the orthopaedic surgeon. The study period was from January 1983 to December 1995, inclusive.

RESULTS

37,383 babies were born during the study period, an average of 2,876 births per annum. The average rate of babies referred to the orthopaedic surgeon was 12.8 per 1,000 (range 5.5-28.2 per 1,000). The average incidence of babies splinted early was 7.19 per 1,000 (range 4.0-14.1 per 1,000) with no discernible increase or decrease over the yrs. In contrast, there was a clear reduction in the incidence of late diagnosed CDH; 42/24,713 births (January 1983-February 1992) compared to only 2/12,673 births (March 1992-December 1995; p < 0.0001. Twelve of the 44 infants (27 per cent) diagnosed with late diagnosed CDH were discovered by the policy of routine hip radiographs at 6 months of age of all babies born by breech presentation (2/12) or those with a positive family history of CDH in a first degree relative (10/12). Six others had a diagnosis of CDH confirmed by X-rays done at 6 months of age because of doubts about their examination in the newborn period.

CONCLUSIONS

Nursing infants in the supine or lateral position and the introduction of a single hip screener were associated with a reduction in the incidence of late diagnosed CDH. Routine hip radiographs of high risk infants at 6 months of age proved to be a valuable safety net in detecting a significant proportion of previously undetected infants with CDH.

Phenotypic analysis of lymphocyte subpopulations in lymph nodes draining the ear following exposure to contact allergens and irritants

The murine local lymph node assay (LLNA) measures in vivo proliferation in draining lymph nodes (DLN) following topical exposure to chemicals to assess contact sensitization potential. However, proliferation has also been observed with some irritants. To further characterize events in the DLN during the LLNA and distinguish allergens from irritants, phenotypic analysis of lymphocyte subsets was made following topical exposure. In preliminary studies, mice were treated on the ears for 3 consecutive days, and 48 hr following the final application, analysis of CD3, CD4, CD8, and B220 expression was evaluated by flow cytometry. The allergens oxazolone (OXAZ) and picryl chloride (TNCB) and the irritant benzalkonium chloride (BC) increased cell number compared to vehicle. The increase in lymph node cellularity for these materials was due to an increase in the total number of T and B lymphocytes. Interestingly, even though contact sensitization is a cell-mediated immune response (Th1), mice exposed to the contact allergens showed a preferential increase in B lymphocytes in the DLN as seen by an increase in the percentage of B220+ cells. The percentage of B220+ cells was 13.1 and 36.1% for OXA and TNCB, respectively, compared to percentages of 7.4 and 9.3% for irritant and vehicle, respectively. With some allergens, a concomitant decrease in the percentage of CD3+ cells was seen. Time course studies demonstrated the increase in the percentage of B220+ cells was seen in allergen treated mice by 24 hr after the final application of material, plateaued by 48 hr, and was still elevated by 96 hr. In allergen-treated mice, percentages of B220+ cells increased dose dependently. Further studies were performed to evaluate additional contact allergens and irritants and determine if evaluation of flow cytometric parameters could potentially identify contact allergens and differentiate them from irritants. Analysis of data from these studies, which examined a total of five contact allergens and six irritants, showed that the modifications to the LLNA improved the identification of irritants and allergens in individual experiments by including both phenotypic analysis of the DLN and cell number per node as endpoints rather than either endpoint alone.

An octadecanoid pathway mutant (JL5) of tomato is compromised in signaling for defense against insect attack

The activation of defense genes in tomato plants has been shown to be mediated by an octadecanoic acid-based signaling pathway in response to herbivore attack or other mechanical wounding. We report here that a tomato mutant (JL5) deficient in the activation of would-inducible defense genes is also compromised in resistance toward the lepidopteran predator Manduca sexta (tobacco hornworm). Thus we propose the name defenseless1 (def1) for the mutation in the JL5 line that mediates this altered defense response. In experiments designed to define the normal function of DEF1, we found that def1 plants are defective in defense gene signaling initiated by prosystemin overexpression in transgenic plants as well as by oligosaccharide (chitosan and polygalacturonide) and polypeptide (systemin) elicitors. Supplementation of plants through their cut stems with intermediates of the octadecanoid pathway indicates that def1 plants are affected in octadecanoid metabolism between the synthesis of hydroperoxylinolenic acid and 12-oxo-phytodienoic acid. Consistent with this defect, def1 plants are also compromised in their ability to accumulate jasmonic acid, the end product of the pathway, in response to wounding and the aforementioned elicitors. Taken together, these results show that octadecanoid metabolism plays an essential role in the transduction of upstream would signals to the activation of antiherbivore plant defenses.

An octadecanoid pathway mutant (JL5) of tomato is compromised in signaling for defense against insect attack

The activation of defense genes in tomato plants has been shown to be mediated by an octadecanoic acid-based signaling pathway in response to herbivore attack or other mechanical wounding. We report here that a tomato mutant (JL5) deficient in the activation of would-inducible defense genes is also compromised in resistance toward the lepidopteran predator Manduca sexta (tobacco hornworm). Thus we propose the name defenseless1 (def1) for the mutation in the JL5 line that mediates this altered defense response. In experiments designed to define the normal function of DEF1, we found that def1 plants are defective in defense gene signaling initiated by prosystemin overexpression in transgenic plants as well as by oligosaccharide (chitosan and polygalacturonide) and polypeptide (systemin) elicitors. Supplementation of plants through their cut stems with intermediates of the octadecanoid pathway indicates that def1 plants are affected in octadecanoid metabolism between the synthesis of hydroperoxylinolenic acid and 12-oxo-phytodienoic acid. Consistent with this defect, def1 plants are also compromised in their ability to accumulate jasmonic acid, the end product of the pathway, in response to wounding and the aforementioned elicitors. Taken together, these results show that octadecanoid metabolism plays an essential role in the transduction of upstream would signals to the activation of antiherbivore plant defenses.

The octadecanoid signalling pathway in plants mediates a response to ultraviolet radiation

Many plant genes that respond to environmental and developmental changes are regulated by jasmonic acid, which is derived from linolenic acid via the octadecanoid pathway. Linolenic acid is an important fatty-acid constituent of membranes in most plant species and its intracellular levels increase in response to certain signals. Here we report that irradiation of tomato leaves with ultraviolet light induces the expression of several plant defensive genes that are normally activated through the octadecanoid pathway after wounding. The response to ultraviolet light is blocked by an inhibitor of the octadecanoid pathway and it does not occur in a tomato mutant defective in this pathway. The ultraviolet irradiation maximally induces the defence genes at levels where cyclobutane pyrimidine dimer formation, an indicator of DNA damage, is less than 0.2 dimers per gene. Our evidence indicates that this plant defence response to certain wavelengths of ultraviolet radiation requires the activation of the octadecanoid defence signalling pathway.

Polypeptide signaling for plant defensive genes exhibits analogies to defense signaling in animals

The activation of plant defensive genes in leaves of tomato plants in response to herbivore damage or mechanical wounding is mediated by a mobile 18-amino acid polypeptide signal called systemin. Systemin is derived from a larger, 200-amino acid precursor called prosystemin, similar to polypeptide hormones and soluble growth factors in animals. Systemin activates a lipid-based signaling cascade, also analogous to signaling systems found in animals. In plants, linolenic acid is released from membranes and is converted to the oxylipins phytodienoic acid and jasmonic acid through the octadecanoid pathway. Plant oxylipins are structural analogs of animal prostaglandins which are derived from arachidonic acid in response to various signals, including polypeptide factors. Constitutive overexpression of the prosystemin gene in transgenic tomato plants resulted in the overproduction of prosystemin and the abnormal release of systemin, conferring a constitutive overproduction of several systemic wound-response proteins (SWRPs). The data indicate that systemin is a master signal for defense against attacking herbivores. The same defensive proteins induced by wounding are synthesized in response to oligosaccharide elicitors that are generated in leaf cells in response to pathogen attacks. Inhibitors of the octadecanoid pathway, and a mutation that interrupts this pathway, block the induction of SWRPs by wounding, systemin, and oligosaccharide elicitors, indicating that the octadecanoid pathway is essential for the activation of defense genes by all of these signals. The tomato mutant line that is functionally deficient in the octadecanoid pathway is highly susceptible to attacks by Manduca sexta larvae. The similarities between the defense signaling pathway in tomato leaves and those of the defense signaling pathways of macrophages and mast cells of animals suggests that both the plant and animal pathways may have evolved from a common ancestral origin.

Results of a phase I trial of a recombinant vaccinia virus that expresses carcinoembryonic antigen in patients with advanced colorectal cancer

BACKGROUND

The inadequacy of systemic treatments of advanced colorectal cancer has aroused interest in biologic therapy. Recent animal models have demonstrated the efficacy and safety of a recombinant vaccine that contains vaccinia and the gene for carcinoembryonic antigen (rV-CEA).

METHODS

A phase I clinical trial of rV-CEA was conducted to assess vaccine toxicities, the maximum tolerated dosage, resulting immune activities, and tumour responses. A dose-escalation protocol was devised for three concentrations. Six patients per dosage were each to receive three vaccinations.

RESULTS

Seventeen patients with advanced colorectal cancer received a total of 44 vaccinations. Mild local and systemic reactions-comparable to those seen with vaccinia alone-were observed and were typically associated with the first vaccination. No significant complications or deaths were caused by the rV-CEA. In particular, no autoimmune colitis developed, nor did leukopenia occur, despite some homology between CEA and leukocyte antigens. All three vaccine concentrations were equally well tolerated. Most patients demonstrated tumor progression by clinical and radiographic parameters and by CEA levels. Immune assays are pending.

CONCLUSIONS

This phase I trial demonstrated the safety of rV-CEA in patients with advanced colorectal cancer. Future clinical studies are warranted and will likely be influenced by investigations of the immune responses to the vaccine.

Molecular cloning of a tomato leaf cDNA encoding an aspartic protease, a systemic wound response protein

A full-length cDNA encoding an aspartic protease (LeAspP) has been cloned from a tomato leaf cDNA library. Using LeAspP cDNA as a probe in gel blots, LeAspP mRNA was shown to be systemically induced in tomato leaves by wounding. Application of methyl jasmonate to leaves of intact tomato plants, or supplying systemin to young tomato plants through their cut stems, induces synthesis of LeAspP mRNA. LeAspP message is regulated in tomato similar to several systemic wound response proteins (swrps) that are part of the defense response in tomato plants directed against herbivore attacks.

Further evaluation of the local lymph node assay in the final phase of an international collaborative trial

The local lymph node assay (LLNA) is a method used for the prospective identification in mice of chemicals that have the potential to cause skin sensitization. We report here the results of the second and final phase of an international trial in which the performance of the assay has been evaluated using seven test materials in five independent laboratories. The additional chemicals examined here included compounds which are considered less potent allergens than some of those tested in the first phase of the investigation, and includes hexylcinnamic aldehyde (HCA), a chemical recommended by the Organization for Economic Cooperation and Development (OECD) as a positive control for skin sensitization studies. In each laboratory all skin sensitizing chemicals examined (2,4-dinitrochlorobenzene {DNCB}, HCA, oxazolone, isoeugenal and eugenol) elicited positive responses of comparable magnitude as judged by the derived lowest concentration of test chemical required to elicit a 3-fold or greater increase in the proliferative activity of draining lymph node cells compared with vehicle-treated controls. We observed that sodium lauryl sulphate, considered to be a non-sensitizing skin irritant, also induced a positive response in the assay. Para-aminobenzoic acid (pABA), a nonsensitizing chemical, was negative at all test concentrations in each laboratory. Some laboratories incorporated minor modifications into the standard assay procedure, including the evaluation of lymph nodes pooled from individual mice rather than treatment groups and the use of statistical analyses. The use of statistics did not markedly change the determination of the lowest concentration yielding a positive response. These data confirm that the local lymph node assay is robust and yields equivalent results when performed independently.

Sexual behaviors and risk factors for HIV infection among men who have sex with men in the Dominican Republic

OBJECTIVE

To describe self-reported types of sexual identity of men who have sex with men (MSM) in the Dominican Republic, assess sociodemographics and behavioral characteristics, and measure the prevalence of HIV-1 and syphilis.

DESIGN

Cross-sectional study of MSM recruited from a variety of community settings.

METHODS

A total of 354 men agreed to participate after giving verbal informed consent. Information was obtained using a standardized questionnaire assessing demographics and AIDS-relevant information. Blood was obtained for HIV and syphilis testing.

RESULTS

Five main sexual identity groups emerged: cross dressers, homosexuals, gigolos, bisexuals and heterosexuals. Receptive anal and oral intercourse were commonly reported by men self-identifying as cross dressers or homosexuals, whereas nearly all of the remaining three groups practiced only insertive intercourse. Sexual contact with women was also commonly reported; overall, consistent condom use was infrequent. HIV antibodies were detected in 11.0% and serologic evidence of syphilis was found in 7.3%. Factors independently associated with HIV infection included serologic evidence of syphilis, having visited at least one of four local brothels in 1975-1985, and having had receptive anal intercourse with four or more partners in the last 12 months.

CONCLUSIONS

Syphilis, sexual practices and social context of sex (commercial sex), rather than sexual identity per se, were associated with HIV infection. The complex social networks of MSM in this setting, the tendency to practice either insertive or receptive sex, but not both, infrequent condom use, high rates of syphilis and the frequency of sex with women need to be taken into account for targeted HIV prevention programs to be successful.

Systemin--a polypeptide defense signal in plants

Insect and pathogen attacks activate plant defense genes within minutes in nearby cells, and within hours in leaves far distant from the sites of the predator attacks. A search for signal molecules involved in both the localized and distal signalling has resulted in the identification of an 18-amino-acid polypeptide, called systemin, that activates defense genes in leaves of tomato plants when supplied at levels as low as fmols/plant. Several lines of evidence support a role for systemin as a wound hormone. As with animal polypeptide hormones, systemin is derived from a larger precursor protein, called prosystemin, by limited proteolysis. Systemin has been shown by autoradiography to be phloemmobile and, by antisense technology, to be an essential component of the wound-inducible, systemic signal transduction system leading to the transcriptional activation of the defensive genes. A search for the receptor of systemin has led to the identification in plant plasma membranes of a systemin-binding protein. However, this protein has properties not of a receptor, but of a furin-like proteinase that cleaves systemin into smaller polypeptides. Systemin and its precursor prosystemin provide prototypes for the emerging possibilities that polypeptide hormones may have broad roles in signalling environmental stress responses, and in regulating plant growth and development as well.

An international evaluation of the murine local lymph node assay and comparison of modified procedures

The murine local lymph node assay is a predictive test for the identification of skin-sensitizing chemicals. The method has been the subject both of national inter-laboratory studies and of extensive comparisons with guinea pig tests. In the investigations reported here, the local lymph node assay has been evaluated further in the context of an international study comprising five independent laboratories. In addition, the influence of minor modifications to the standard assay procedure on the performance of the test has been examined. The modified procedures investigated were exposure of mice for 4 rather than 3 consecutive days, excision of lymph nodes 4 rather than 5 days after the initiation of exposure and the use of an alternative isotope. All five laboratories, irrespective of whether the standard or a modified protocol was used, were able to identify accurately, and with comparable sensitivity, potassium dichromate and 2,4-dinitrochlorobenzene as skin sensitizers. Using standard criteria, none of the laboratories recorded positive responses with methyl salicylate, a non-sensitizer. In the standard protocol, lymph nodes are pooled for each experimental group and the vigor of responses measured as a stimulation index relative to vehicle controls. A stimulation index of 3 or greater is considered to indicate skin-sensitizing potential. One further modification adopted by three of the laboratories was to analyze nodes from individual animals and, thereby, permit statistical evaluation. This allowed a direct comparison of statistical significance with the conventional stimulation index as criteria for a positive response. The data indicate that, while statistical evaluation may provide, in some instances, for small increases in sensitivity, this may be at the expense of some loss of selectivity. There are, however, insufficient data presently to draw firm conclusions regarding the relative value of statistical analysis. These studies demonstrate that the local lymph node assay is sufficiently robust to accommodate minor procedural and technical modifications without material changes in test performance.