Cell biology and genetics of root hair formation in Arabidopsis thaliana

In this review we integrate the information available on the cell biology of root hair formation with recent findings from the analysis of root hair mutants of Arabidopsis thaliana. The mature Arabidopsis root epidermis consists of root-hair-producing cells and non-root-hair-producing cells. Root hair growth begins with a swelling of the outer epidermal wall. It has been postulated that this is due to a pH-mediated localised cell wall loosening. From the bulge a single root hair emerges which grows by tip growth. The root hair tip consists of a vesicle-rich zone and an organelle-rich subapical zone. The vesicles supply new plasma membrane and cell wall material for elongation. The cytoskeleton and its associated regulatory proteins such as profilin and spectrin are proposed to be involved in the targeting of vesicles. Ca2+ influxes and gradients are present in hair tips, but their function is still unclear. Mutants have been isolated with lesions in various parts of the root hair developmental pathway from bulge identity and initiation to control of tip diameter and extent and polarity of elongation.

Mortality association of enhanced CD44v6 expression is not mediated through occult lymphatic spread in stage II colorectal cancer

BACKGROUND AND AIMS

In the absence of other metastatic disease, the presence of lymph node metastasis remains the most important determinant of survival in colorectal cancer (CRC). Cluster designation 44 variant 6 (CD44v6) over-expression is associated with worse outcome in all stages of CRC. The CD44v6 is believed to confer metastatic potential through its facilitation of migration, extravasation and proliferation, although the specific means by which it conveys an adverse prognosis in CRC is unknown. The aim of the present study was to determine if CD44v6 over-expression in Stage II CRC subjects was associated with the presence of lymph node micrometastases.

METHODS

We assessed tumour CD44v6 expression in 43 randomly sampled subjects who had resections for Stage II CRC between 1984 and 1991 by using immunohistochemistry. Micrometastases were sought in corresponding lymph node (LN) sections using keratin immunohistochemistry.

RESULTS

There was a statistical trend between tumour CD44v6 over-expression and mortality (P = 0.09) and a significant relationship between LN cytokeratins and mortality (P = 0.01). There was no association between the detection of LN cytokeratins and tumour CD44v6 over-expression.

CONCLUSION

We conclude that the adverse survival effect of CD44v6 over-expression is not mediated though lymphatic spread and postulate that it may therefore facilitate haematogenous metastasis.

Sequencing of oligosaccharides by collision-induced dissociation matrix-assisted laser desorption/ionization mass spectrometry

A study of the collision-induced dissociation post-source decay (PSD) spectra of free oligosaccharides is presented. These spectra, when obtained with helium as collision gas, show (1,5)X fragments containing the reducing end sugar. The presence of these fragments permits Y ions and, consequently, B and C peaks to be identified. This is a common behaviour from which it has been possible to delineate a general method for the easy assignment of the peaks in PSD spectra of underivatized neutral sugars, allowing the sequence of a real unknown to be obtained.

The detection of cytokeratins in lymph nodes of Duke's B colorectal cancer subjects predicts a poor outcome

OBJECTIVES

The objectives of this study were to examine the frequency of lymph node micrometastases detected by keratin immunohistochemistry and their relationship with survival behaviour.

METHODS

A total of 133 consecutive patients staged as Duke's B, who had curative resection for colorectal cancer (CRC), comprised the study population. Patients who had died of a non-CRC-related cause or who became lost to follow-up were excluded, resulting in an amended population of 100. Study end-points were defined as disease-free survival of 5 years or CRC-related death. Paraffin-embedded lymph node sections were stained with a commercial cytokeratin antibody using a standard avidin-biotin technique.

RESULTS

One quarter of subjects had micrometastases. Fifty-six per cent of subjects with positive lymph nodes had an adverse outcome, compared with 11% of subjects with negative nodes. A highly significant association was found between lymph node cytokeratin expression and mortality in both the univariate (log rank P = 0.0001) and multivariate (Cox proportional hazards P = 0.0123) analysis.

CONCLUSIONS

Lymph node micrometastases detected by this inexpensive and simple technique are significantly associated with mortality in Duke's B CRC. This technique may be used to select patients for adjuvant chemotherapy.

Immunohistochemical detection of mutant p53 protein in regional lymph nodes is associated with adverse outcome in stage II colorectal cancer

Epidemiologic data identifies a cohort of Duke's B (CRC) patients whose survival more closely matches that of Duke's C. Lymph node micrometastases may account for this discrepancy. Lymph node expression of mutant p53 protein (Mp53P) has been linked to a reduction in survival in Japanese Duke's B patients. We aimed to determine the significance of nodal p53 expression in European Duke's B patients using immunohistochemistry. The study comprised 134 consecutive patients who had resections for CRC between 1984 and 1991. End points were 5 year disease free survival or CRC related death. Thirty-four subjects did not achieve end points and were excluded. We examined tumour and nodal sections for Mp53P by immunohistochemistry and correlated this with survival using a Kaplan-Meier (KM) and a Cox Proportional hazards model (CPHT). Five year survival was 73%. Fifty-eight percent of primary tumours expressed Mp53P. Tumour p53 expression did modulate survival behavior. Twenty-six percent of subjects' lymph nodes expressed Mp53P. Fifty-three per cent of those with positive and 17% of those with negative lymph nodes died of recurrence. The relative risk for nodal Mp53P expression was 3.1. There was a significant univariate relationship between lymph node p53 expression and mortality. (Log Rank p = 0.028). Multivariate analysis also showed a significant relationship with mortality. (CPHT p = .03). We conclude that lymph node expression of Mp53P is associated with increased mortality in Duke's B CRC.

Immunohistochemistry of the Hfe protein in patients with hereditary hemochromatosis, iron deficiency anemia, and normal controls

In 1996 two mutations in Hfe, the gene affected in hereditary hemochromatosis, were identified as C282Y (c.845G. A) and H63D (c.187C. G). Immunohistochemical studies have localized the protein product of Hfe to the deep crypts of the duodenum, the maximum site of iron absorption. To date, there are no published data on the cellular location and regulation of Hfe in patients with hemochromatosis who are homozygous for C282Y. The aim of this study was to identify the cellular localization of Hfe in genotyped individuals and to study possible regulation of this protein by the mutations described in the Hfe gene locus and iron deficiency. Duodenal biopsy specimens and serum for iron, ferritin, and transferrin saturation were taken from controls (n = 10) and patients with hereditary hemochromatosis (n = 10) and iron deficiency anemia (n = 10). All participants were genotyped for C282Y and H63D mutations. Expression of Hfe in the duodenum was demonstrated by immunohistochemistry. Hfe was expressed in the deep crypts of the duodenum in all three groups in a perinuclear fashion. Hfe staining was weaker in the hemochromatosis and iron deficiency patients (mean transferrin saturation 69.6%, SD 23% and 15%, SD 11%, respectively) when compared to controls (mean transferrin saturation 33.1%, SD 15%). There was no difference in the intensity of Hfe staining within the hemochromatosis group who were iron overloaded when compared to their iron-depleted counterparts. In summary, Hfe is expressed strongly in the deep crypts of the small intestine of normal subjects. Homozygosity for C282Y and conditions of iron deficiency result in a downregulation of Hfe. Furthermore, Hfe is not regulated by therapeutic iron depletion in patients with hemochromatosis who are homozygous for the C282Y mutation.

Sequence and analysis of chromosome 4 of the plant Arabidopsis thaliana

The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the sequence of chromosome 4. Analysis of 17.38 megabases of unique sequence, representing about 17% of the genome, reveals 3,744 protein coding genes, 81 transfer RNAs and numerous repeat elements. Heterochromatic regions surrounding the putative centromere, which has not yet been completely sequenced, are characterized by an increased frequency of a variety of repeats, new repeats, reduced recombination, lowered gene density and lowered gene expression. Roughly 60% of the predicted protein-coding genes have been functionally characterized on the basis of their homology to known genes. Many genes encode predicted proteins that are homologous to human and Caenorhabditis elegans proteins.

Functional electrical stimulation exercise increases GLUT-1 and GLUT-4 in paralyzed skeletal muscle

The study purpose was to determine the effect of functional electrical stimulation (FES)-leg cycle ergometer training (30 minutes on 3 d/wk for 8 weeks) on the GLUT-1 and GLUT-4 content of paralyzed skeletal muscle. Biopsy samples of vastus lateralis muscle were obtained pre- and post-training from five individuals with motor-complete spinal cord injury ([SCI] four men and one woman aged 31 to 50 years, 3 to 25 years postinjury involving C5-T8). Western blot analysis indicated that GLUT-1 increased by 52% and GLUT-4 increased by 72% with training (P < .05). This coincided with an increase in the muscle oxidative capacity as indicated by a 56% increase in citrate synthase (CS) activity (P < .05) and an improvement in the insulin sensitivity index as determined from oral glucose tolerance tests (P < .05). It is concluded that FES endurance training is effective to increase glucose transporter protein levels in paralyzed skeletal muscle of individuals with SCI.

Association of the HLA-DRB1*01 allele with spontaneous viral clearance in an Irish cohort infected with hepatitis C virus via contaminated anti-D immunoglobulin

BACKGROUND/AIMS

The host's immune response may influence the course of hepatitis C virus (HCV) infection. The aim of this study was to examine the distribution of HLA Class II DRB1* alleles in a homogeneous cohort of individuals who were infected with HCV-contaminated anti-D immunoglobulin, and to compare frequencies of alleles in individuals with spontaneous viral clearance to those with chronic HCV infection.

METHODS

HLA DRB1* typing was performed on whole blood or serum from 157 females. Of these, 73 had spontaneously recovered from infection (persistently HCV RNA negative), while 84 had chronic HCV infection (persistently HCV RNA positive). A group of 5000 healthy bone marrow donors served as a control population.

RESULTS

No significant differences were observed between individuals with spontaneous viral clearance or chronic HCV infection for age, sex, alcohol consumption, source or duration of infection. The DRB1*01 allele was found significantly more frequently in individuals with viral clearance compared to those with chronic infection (27.4% vs. 7.1% p = 0.001, odds ratio OR = 4.9, pc = 0.01). No significant association was shown between severity of liver disease and DRB1* alleles.

CONCLUSIONS

DRB1*01 is associated with spontaneous viral clearance in an Irish cohort infected with HCV via contaminated anti-D immunoglobulin. HLA-DRB1* genes do not appear to influence severity of liver disease. These results suggest that host HLA-DRB1* alleles are important contributors to disease outcome.

Depressive symptomatology and specificity of social support

Psychosocial interventions should be based on research which reflects the multidimensionality of psychosocial constructs. This study investigated six categories of social support which were associated with depressive symptomatology in a sample of 531 college students. The Social Provisions Scale was used to measure social support while the Center for Epidemiological Studies-Depression Scale was used to measure depressive symptomatology. Standard multiple regression analysis was used to analyze the variance contributed by each of the six categories of social support found on the Social Provisions Scale to depressive symptomatology. Specifically, the following categories of social support were significantly associated with depressive symptomatology: Reassurance of Worth (for male and female respondents) and Attachment (for females only). Implications for practice and research are discussed.

Effect of tamoxifen on sexual functioning in patients with breast cancer

PURPOSE

To define the incidence of sexual dysfunction in a population of women with breast cancer treated with tamoxifen.

PATIENTS AND METHODS

Breast cancer patients with a performance status of 0 to 2 who had been treated with tamoxifen for 2 to 24 months completed the following measures: the Center for Epidemiologic Studies-Depression Scale, the Sexual History Form, and the Breast Cancer Prevention Trial Symptom Checklist. Forty-nine of the participants underwent gynecologic examinations with vaginal smears for determination of estrogen effect.

RESULTS

Fifty-seven women were entered onto the trial. Sexual desire, arousal, and ability to achieve orgasm were comparable to norms established in participants in the Tamoxifen Prevention Trial (National Surgical Adjuvant Breast and Bowel Project P-01). Pain, burning, or discomfort with intercourse was reported in 54% of patients and did not correlate with age, surgical treatment of the primary cancer, or chemotherapy. Estrogen effect was seen on the vaginal smears of 34 of 49 participants and was more common in older patients (P = .054). The presence of estrogen effect correlated with negative reactions during sex (P = .02) and vaginal dryness or tightness (P = .046).

CONCLUSION

Women treated with tamoxifen in the adjuvant setting experienced symptoms of sexual dysfunction. The individual contributions of chemotherapy and tamoxifen to sexual dysfunction warrant prospective study.

A respiratory challenge model for infection with Bordetella pertussis: application in the assessment of pertussis vaccine potency and in defining the mechanism of protective immunity

The evaluation of vaccines for human use usually requires the development of appropriate animal models and the definition of laboratory correlates of immunity. Traditionally whole cell pertussis vaccines have been controlled by using an active mouse protection test, which measures protection following intracerebral challenge with Bordetella pertussis. However, this test is unsuitable for assessing the potency of the new generation acellular pertussis vaccines. In the present study we demonstrate that a murine respiratory challenge model for infection with B. pertussis is suitable for assessing the potency of acellular and whole cell pertussis vaccines. To allow standardization of different vaccines we have expressed the area under the clearance curve for immunized mice as a ratio of that for non-immunized controls to obtain a potency index. A comparison of estimated vaccine efficacy in children with potency in the murine model results in a highly significant correlation (r = 0.976, p < 0.001). Furthermore, we have used this model to define the protective mechanism of immunity against respiratory infection with B. pertussis and demonstrate a requirement for both specific T and B cells. In accordance with studies in humans, no clear relationship was observed between monotypic serum antibody responses against the putative protective antigens of B. pertussis and protection. In contrast, the most potent protection was observed when the T cell response is polarized to the Th1 subtype.

Hemochromatosis in Ireland and HFE

Sixty patients diagnosed with hereditary hemochromatosis with grade 3 or 4 hepatic iron overload and 18 patients diagnosed with hereditary hemochromatosis who had less than grade 3 hepatic iron overload were examined for the HFE gene mutations, 845A (C282Y) and 187G (H63D). Control samples were obtained from 109 randomly selected individuals. Fifty-six of 60 unrelated hereditary hemochromatosis patients (93%) with grade 3 or 4 hepatic iron deposition were homozygous for the C282Y mutation. Fourteen of the 18 hereditary hemochromatosis patients with <3+ iron deposition (76%) were homozygous for the C282Y mutation. Three of 8 patients who were heterozygous for the C282Y mutation were also heterozygous for the H63D mutation. Thirty-one of 109 control individuals were heterozygous for the C282Y mutation and 27 were heterozygous for the H63D mutation. Our finding that 93% of hereditary hemochromatosis patients who fulfil standard diagnostic criteria are homozygous for the C282Y mutation provides clear evidence that this mutation is strongly associated with hereditary hemochromatosis. The allele frequency of 14% for the C282Y mutation in our control population is the highest reported and supports the hypothesis of a Celtic origin for the hereditary hemochromatosis gene.

A murine model in which protection correlates with pertussis vaccine efficacy in children reveals complementary roles for humoral and cell-mediated immunity in protection against Bordetella pertussis

The results of phase 3 efficacy trials have shown that acellular and whole-cell pertussis vaccines can confer protection against whooping cough. However, despite the advances in vaccine development, clinical trials have not provided significant new information on the mechanism of protective immunity against Bordetella pertussis. Classical approaches based on measurement of antibody responses to individual antigens failed to define an immunological correlate of protection. A reliable animal model, predictive of acellular and whole-cell pertussis vaccine potency in children, would facilitate an elucidation of the mechanism of immune protection against B. pertussis and would assist in the regulatory control and future development of pertussis vaccines. In this study, we have shown that the rate of B. pertussis clearance following respiratory challenge of immunized mice correlated with vaccine efficacy in children. Using this model together with mice with targeted disruptions of the gamma interferon (IFN-gamma) receptor, interleukin-4 or immunoglobulin heavy-chain genes, we have demonstrated an absolute requirement for B cells or their products in bacterial clearance and a role for IFN-gamma in immunity generated by previous infection or immunization with the whole-cell pertussis vaccine. The results of passive immunization experiments suggested that protection early after immunization with acellular pertussis vaccines is mediated by antibody against multiple protective antigens. In contrast, more complete protection conferred by previous infection or immunization with whole-cell pertussis vaccines reflected the induction of Th1 cells. Our findings suggest that the mechanism of immunity against B. pertussis involves humoral and cellular immune responses which are not directed against a single protective antigen and thus provide an explanation for previous failures to define an immunological correlate of protection.

Distinct T-cell subtypes induced with whole cell and acellular pertussis vaccines in children

Recent clinical trials have demonstrated that new generation acellular pertussis vaccines can confer protection against whooping cough. However, the mechanism of protective immunity against Bordetella pertussis infection induced by vaccination remains to be defined. We have examined cellular immune responses in children immunized with a range of acellular and whole cell pertussis vaccines. Immunization of children with a potent whole-cell vaccine induced B. pertussis-specific T cells that secreted interferon-gamma (IFN-gamma), but not interleukin-5 (IL-5). In contrast, T cells from children immunized with acellular pertussis vaccines secreted IFN-gamma and/or IL-5 following stimulation with B. pertussis antigens in vitro. These observations suggest that protective immunity conferred by whole-cell vaccines, like natural immunity, is mediated by type 1 T cells, whereas the mechanism of immune protection generated with acellular vaccines may be more heterogeneous, involving T cells that secreted type 1 and type 2 cytokines.

Melatonin modulates vascular smooth muscle tone

The molecular cloning of a family of melatonin receptors has created a renewed interest in the diverse actions of the hormone melatonin. The radioligand 2-[125I]iodomelatonin has identified potential sites of action for melatonin throughout the central nervous system and periphery of numerous species. Interestingly, in addition to the suprachiasmatic nucleus (the "biological clock"), 2-[125I]iodomelatonin binding sites have been localized to the rat caudal and cerebral arteries. Furthermore, in vitro, melatonin has been shown to induce a concentration-dependent vasoconstriction of rat caudal and cerebral arteries, and pig and human coronary arteries. The lack of melatonin receptor subtype-selective agonists and antagonists prevents the full pharmacological characterization of these responses. The physiological significance of the in vitro vasoconstrictive properties is far from clear, however; in rats, melatonin has been shown to reduce cerebral blood flow. The widespread use of melatonin warrants appropriately designed studies to probe the role of melatonin and its receptors in the modulation of in vitro vascular tone.

Building an effective corporate compliance plan

Corporate compliance plans are essential for healthcare organizations to cope with, and perhaps even stave off, investigations arising from allegations of illegal business practices. Initial development and implementation of a corporate compliance plan can be facilitated through four steps: determining the content of the code of conduct, determining how the code will be distributed, assigning responsibility for implementing the plan, and appointing a compliance task force to guide the implementation process. Special attention should be paid to education requirements of the United States Sentencing Guidelines to see that all employees understand and can apply provisions of the plan.

Fructosamine concentrations in hyperglycemic cats

The aims of this study were 1) to establish a reference range for fructosamine in cats using a commercial fructosamine kit; 2) to demonstrate that the fructosamine concentration is not increased by transient hyperglycemia of 90 min duration, simulating hyperglycemia of acute stress; and 3) to determine what percentage of blood samples submitted to a commercial laboratory from 95 sick cats had evidence of persistent hyperglycemia based on an elevated fructosamine concentration. Reference intervals for the serum fructosamine concentration were established in healthy, normoglycemic cats using a second generation kit designed for the measurement of the fructosamine concentration in humans. Transient hyperglycemia of 90 min duration was induced by IV glucose injection in healthy cats. Multisourced blood samples that were submitted to a commercial veterinary laboratory either as fluoride oxalated plasma or serum were used to determine the percentage of hyperglycemic cats having persistent hyperglycemia. The reference interval for the serum fructosamine concentration was 249 to 406 mumol/L. Transient hyperglycemia of 90 min duration did not increase the fructosamine concentration and there was no correlation between fructosamine and blood glucose. In contrast, the fructosamine concentration was correlated with the glucose concentration in sick hyper- and normoglycemic cats. It is concluded that the fructosamine concentration is a useful marker for the detection of persistent hyperglycemia and its differentiation from transient stress hyperglycemia. Fructosamine determinations should be considered when blood glucose is 12 to 20 mmol/L and only a single blood sample is available for analysis.