Comparative evaluation of cancer chemopreventive efficacy of alpha-tocopherol and quercetin in a murine model

Chemopreventive efficacy and the mode of action of alpha-tocopherol and quercetin, both known to possess anti-oxidant properties, were evaluated during carcinogenesis in uterine cervix of mice by chronic exposure to methylcholanthrene. Oral administration of alpha-tocopherol and quercetin could reduce the genotoxic effect of the carcinogen as revealed by the micronucleus frequency in vaginal epithelial cells. Both could restrict the progression of dysplastic changes in cervix uteri leading to carcinoma in-situ but the influence of the quercetin was more pronounced. A decrease in lipid peroxides following ingestion of these agents suggests that their chemopreventive action is due to their protective role on DNA damage by free radicals. Increased glutathione and glutathione-s-transferase also indicate their involvement in detoxification. While alpha-tocopherol activated the PBL response towards mitogenic stimulation, quercetin had no such effect.

Compact measurement of low-PMD optical telecommunication fibers

Accurate polarization mode dispersion (PMD) measurements on modern telecommunication fiber involve significant fiber layout and handling problems. These problems severely limit the quality and quantity of data that can be taken. A new method is proposed for measuring PMD using a large diameter collapsible spool with localized external perturbation (LEP). This method allows the necessary repeated measurements, and virtually eliminates environmental effects, which complicate measurements of low-PMD modern fibers. It is shown that the method produces nearly identical PMD results to a more laborious, conventional method.

Association of deletion in the chromosomal 8p21.3-23 region with the development of invasive head & neck squamous cell carcinoma in Indian patients

BACKGROUND & OBJECTIVES

Deletions in chromosome 8 (chr.8) have been shown to be necessary for the development of head and neck squamous cell carcinoma (HNSCC). Attempts have been made in this study to detect the minimal deleted region in chr.8 associated with the development of HNSCC in Indian patients and to study the association of clinicopathological features with the progression of the disease.

METHODS

The deletion mapping of chr.8 was done in samples from 10 primary dysplastic lesions and 43 invasive squamous cell carcinomas from the head and neck region of Indian patients to detect allelic alterations (deletion or size alteration) using 12 highly polymorphic microsatellite markers. The association of the highly deleted region was correlated with the tumour node metastasis (TNM) stages, nodal involvement, tobacco habit and human papilloma virus (HPV) infection of the samples.

RESULTS

High frequency (49%) of loss of heterozygosity (LOH) was seen within 13.12 megabase (Mb) region of chromosomal 8p21.3-23 region in the HNSCC samples, whereas the dysplastic samples did not show any allelic alterations in this region. The highest frequency (17%) of microsatellite size alterations (MA) was observed in the chr.8p22 region. The loss of short arm or normal copy of chr.8 and rare bi-allelic alterations were seen in the stage II-IV tumours (939, 5184, 2772, 1319 and 598) irrespective of their primary sites. The highly deleted region did not show any significant association with any of the clinical parameters. However, HPV infection was significantly associated (P < 0.05) with the differentiation grades and overall allelic alterations (LOH/MA) of the samples.

INTERPRETATION & CONCLUSION

Our data indicate that the 13.12 Mb deleted region in the chromosomal 8p21.3-23 region could harbour candidate tumour suppressor gene(s) (TSGs) associated with the progression anti invasion of HNSCC tumours in Indian patients.

Allelic imbalance at chromosome 11 in head and neck squamous cell carcinoma in an Indian patient population

BACKGROUND

Genetic instability of chromosome 11 is a frequent event in many solid tumours, including head and neck squamous cell carcinoma (HNSCC).

AIMS

To perform allelic imbalance analysis of cytogenetically mapped altered regions of human chromosome 11 in patients with HNSCC from eastern India.

METHODS

Genomic alterations were investigated using highly polymorphic microsatellite markers in both HNSCC and leukoplakia tissues.

RESULTS

Microsatellite markers D11S1758 from 11p13-15 and D11S925 from 11q23.3-24 had the highest frequency (38% and 32%, respectively) of loss of heterozygosity among all the markers analysed. Allelic loss at the marker D11S925 was seen in both leukoplakia and in all stages of HNSCC tumour tissues suggesting that it is an early event in HNSCC tumorigenesis. Microsatellite size alteration was also found to be high (> 20%) in several markers. In leukoplakia samples microsatellite instability was seen at a higher frequency than loss of the allele, indicating such alterations might initiate the process of tumorigenesis in HNSCC.

CONCLUSIONS

The high rate of chromosomal alterations at 11q21-24 in HNSCC suggests the presence of a putative tumour suppressor gene in this region.

Tea can protect against aberrant crypt foci formation during azoxymethane induced rat colon carcinogenesis

Tea shows many health promoting activities including chemopreventive action during carcinogenesis due to the presence of antioxidative polyphenolic constituents. The present experiment evaluated the anticarcinogenic role of black tea infusion on azoxymethane induced colonic preneoplastic lesions, the aberrant crypt foci in Sprague-Dawley rats. Rats were injected with azoxymethane (15 mg/kg b.w.) and received oral administration of 1% and 2% (w/v) tea infusions from first day of carcinogen application. This treatment was continued for twelve weeks and assessed for aberrant crypt foci and compared with untreated carcinogen control group. Levels of lipid peroxidation were determined in liver as well as in colon tissue. During initiation phase of carcinogenesis, glutathione-S-transferase (GST) and glutathione peroxidase (GPx) activities were also evaluated. Significant reduction in the number of aberrant crypt foci and levels of lipid peroxidation among the tea-treated groups were observed. Induction of GST and GPx activities was noted during the initiation phase of carcinogenesis. Results of the present study indicate that the protective effect of black tea infusions may be due to an outcome of antioxidative influence of tea components on azoxymethane induced carcinogenesis.

The emergence of the menopause in India

A total of 130 million Indian women are expected to live beyond the menopause into old age by 2015. The menopause is emerging as an issue owing to rapid globalization, urbanization, awareness and increased longevity in urban middle-aged Indian women, who are evolving as a homogeneous group. Improved economic conditions and education may cause the attitude of rural working women to be more positive towards the menopause. However, most remain oblivious of the short- and long-term implications of the morbid conditions associated with middle and old age, simply because of lack of awareness, and the unavailability or ever-increasing cost of the medical and social support systems. Evidence-based medicine is accessible to still only a few Indian women. Most menopausal women go untreated or use unproven alternative therapies.

Sequential deletions in both arms of chromosome 9 are associated with the development of head and neck squamous cell carcinoma in Indian patients

In the deletion mapping of chromosome (chr) 9 in head and neck lesions of the Indian patient population by microsatellite markers, we have identified four discrete areas (D1-D4) with high loss of heterozygosities (LOHs) viz. 9p24-p23 (D1), 9p22-p21 (D2), 9q11-q13 (D3) and 9q22.3 (D4) regions. The deletions in D2 and D4 regions were suggested to be essential for the development of dysplastic lesions of head and neck, whereas the deletions in D1 and D3 regions were responsible for progression of the dysplastic lesions to early invasive head and neck squamous cell carcinoma (HNSCC). The microsatellite size alterations (MAs) were observed in the chromosomal 9pter-p23, 9p22-p21(D2), 9q13 and 9q21.1-q21.2 regions with gradual increase during progression of the tumor. Additional chromosomal alterations like loss of normal copy of chr.9 and biallelic alterations were also seen in our samples. There is a correlation between HPV infection with TNM stages, histopathological grades and LOHs at D1 and D4 regions. Whereas tobacco habit is associated with the occurrence of LOHs at D1 and LOHs / MAs at D2 region.

Tomato and garlic can modulate azoxymethane-induced colon carcinogenesis in rats

Tomato (Lycopersicon esculentum) and garlic (Allium cepa) are important constituents of the human diet. Compounds like diallyl sulfides, diallyl disulfides and quercetin, which are active components of garlic, have known anti-inflammatory, antimutagenic activities. Similarly, active components in tomato, such as kaempferol and chlorogenic acid, have antimutagenic activities and lycopene is the most active oxygen quencher with potential chemopreventive activities. In view of this, an endeavour was made to evaluate the anticarcinogenic effect, if any, of tomato and garlic consumption individually and in combination on azoxymethane-induced colonic precancerous lesion, the aberrant crypt foci in animal model. Sprague-Dawley rats (4-5 weeks old) were injected with azoxymethane (15 mg/kg b.w.) and orally administered with 2% (w/v) of tomato, garlic and a combination of both. After 12 weeks of first azoxymethane injection, colons were assessed for aberrant crypt foci and compared with the carcinogen control group. Lipid peroxidation level and glutathione-S-transferase (GST) activity were assessed in liver as well as in colon. Furthermore, in situ cell proliferation and apoptosis were estimated using the Brdu incorporation method and TUNEL method respectively. It was observed that aberrant crypt foci were reduced in all treated groups (by 32.11% in garlic, by 76.14% in tomato and by 55.96% in the combination group). Among treated groups, GST activity was found to be induced in both liver and colon, whereas considerable reduction in lipid peroxidation level was observed in liver as well as in colon with respect to the carcinogen control group. Significant reduction in Brdu labelling index and increase in apoptotic index in colon was noted in the treated groups. These results suggest that tomato and garlic suspensions have a protective effect on colon carcinogenesis, which is mediated by modulation of different biological pathways during carcinogenesis.

Haplotype structure of TP53 locus in Indian population and possible association with head and neck cancer

It has been proposed that a constellation of three TP53 polymorphisms (intron 3 16 bp duplication, codon 72 BstUI, and intron 6 Nci I RFLP at nt 13494) constitute a haplotype predictive of increased cancer risk. We have estimated the allele frequency of these polymorphisms in three endogamous Indian ethnic populations from three different geographic locations (viz. Iyer from south India, Brahmin from central India and Mahishya from eastern India), as well as in head and neck squamous cell carcinoma (HNSCC) patients, and in ethnically matched normal individuals from the eastern region of India. The genotype distributions and allele frequencies of the three polymorphisms in all but one population, as well as in patients, showed a good fit to Hardy-Weinberg equilibrium. Strong linkage disequilibria were observed between all loci in every population examined, except for the 16bp-Nci I haplotype in the Mahishya population. The Mahishya population differed significantly from the other two populations with respect to differences in allele frequency and haplotype frequency. Although there were no significant differences in genotypic frequency at any of the loci between HNSCC patients and the matched control population, the minor allele frequency of codon 72 and intron 3 16 bp polymorphisms showed significant variation. Variation in overall haplotype frequency between patients and normal individuals was significant (p = 0.036) when two rare haplotypes 2-1-2 and 1-2-1 were combined. The rare haplotype 2-1-2 was found to be modestly over represented in HNSCC patients as compared to normal individuals.

Mapping of the candidate tumor suppressor genes' loci on human chromosome 3 in head and neck squamous cell carcinoma of an Indian patient population

The candidate tumor suppressor genes' (TSG) loci on human chromosome 3 (chr.3) were mapped in six dysplastic lesions and 51 primary squamous cell carcinoma from head and neck region of an Indian patient population by using 20 highly polymorphic microsatellite markers. The two chromosomal regions 3p12-13 and 3p21.2-22 have shown the highest losses of heterozygosity (LOHs) of 34.6-38% and 37-46%, respectively with statistically significant clinical correlation's with tobacco habit, positive lymph node and tumor stages. In addition, high frequencies of microsatellite size alterations (MAs) of 16.2-28.5% and 23.8-28.2% were observed in the chromosomal 3p11-13 and 3p21.2-22 regions, respectively, with significant above-mentioned clinical correlation only in the 3p11-13 region. In the dysplastic lesions, the prevalence of LOHs compared to the MAs had indicated that LOHs might be the early events. Five tumors at stage-III/IV seemed to have lost an entire normal copy of chr.3. It was of particular note that 17% (10/57) of the samples showed rare bi-allelic alterations mainly in and around the high LOHs regions. Thus, (1) the gradual increase of LOHs/MAs during progression of the tumor, (2) high frequencies of MAs, (3) rare bi-allelic alterations in and around high LOHs regions and (4) loss of wild type chr.3 in the later stages of tumor development have suggested that such alterations might provide selective growth advantage to the tumors. Also, we propose from our data that the high LOHs regions (3p12-13 and 3p21.2-22) could harbour putative TSG(s), responsible for the development of head and neck squamous cell carcinoma.

Status of minor depression or dysthymia in primary care following a randomized controlled treatment

This report describes the rates of recovery and remission from minor depression or dysthymia in primary care patients three months after completing a randomized controlled treatment trial. The subjects were primary care patients who received > or =4 treatment sessions with Problem-Solving Treatment, paroxetine, or placebo and who completed an independent assessment 3 months after the study (201 with minor depression, 229 with dysthymia). The 17-item Hamilton Rating Scale for Depression (HAMD), semistructured questions about postintervention depression treatments, and baseline medical comorbidity, neuroticism, and social function were the primary measures. For minor depression 76% and for dysthymia 68% of subjects who were in remission at the end of the 11-week treatment trial were recovered (HAMD < or =6) three months after the treatment trial. Of patients who were not in remission at 11 weeks, for minor depression 37% and for dysthymia 31% went on to achieve remission at 25 weeks. The majority of patients chose not to use antidepressants or psychotherapy after the trial. Patients with minor depression that had greater baseline social function and lower neuroticism scores were more likely to be recovered. For patients with minor depression, these findings suggest a need for some matching of continuation and maintenance treatment to patient characteristics rather than uniform, automatic treatment recommendations. Because of the chronic, relapsing nature of dysthymia, practical improvements in encouraging effective continuation and maintenance phases of treatment are indicated.

Cloning and tissue-specific gene expression studies with Dlxin-1, a newly identified transcriptional activator

Dlxin-1, a unique member of the necdin/melanoma associated antigen gene (MAGE) family, is a novel protein that binds Dlxin-5 and regulates its transcriptional function. We have cloned the homology region between Dlxin-1 and necdin from mouse melanoma cells. Here we report the expression cloning, characterization, and detailed tissue-specific expression studies of Dlxin-1. A unique expression pattern of Dlxin-1 emerged from the work wherein strong expression of a 3.2-Kb transcript was observed in mouse brain and embryos. Amongst the representative established cell lines of different tumor categories studied the presence of transcript was detected only in sarcomas and neuroectodermal tumors. Characteristically, lymphomas, leukaemias, adenocarcinomas, and carcinomas did not express Dlxin-1. Also, we observed a growth suppression on ectopic expression of this cDNA possibly due to the close homology shared with necdin, a neuron-specific growth suppressor. The extensive homology of our Dlxin-1 clone to necdin makes it an attractive system to understand the importance of the necdin/MAGE family of molecules in cell cycle regulation.

In vitro bond strengths of resin modified glass ionomer cements and composite resin self-cure adhesives: introduction of an adhesive system with increased bond strength and inhibition of decalcification

This study evaluated the shear bond strength and adhesive remnant index of 5 self-cure adhesives to comparatively evaluate a new adhesive system. Extracted human incisors were randomly divided into 7 test groups of 20 each. Incisor mesh-backed brackets were bonded to the tooth specimens in each group with their respective adhesive according to the manufacturer's instructions. The specimens were thermocycled for 2 weeks at temperatures from 5 degrees to 55 degrees C to simulate oral conditions and debonded using an Instron machine. Acceptable bond strength parameters were present with the Contacto No-Mix (composite resin containing glass ionomer 8.75 MPa) and Fuji Ortho SC with acid conditioning (6.98 MPa). Contacto No-Mix had a higher bond strength (11.2 MPa) when microetching and Megabond were employed than when these adjuncts were not employed. When FUJI Ortho SC specimens were conditioned with polyacrylic acid, they showed a higher bond strength (6.98 MPa) than when bonded to unetched teeth (5.41 MPa). In test 3, EXPT-fluoride adhesive (AF) demonstrated a higher bond strength (13.44 MPa) than both resin composite Contacto No-Mix (8.8 MPa, GAC 7.4 MPa) and FUJI Ortho SC (5.41 MPa). Expt AF (Test 3) and Concise had equal bond strengths, however, the former can potentially release fluoride from the glass ionomer. Although the Ex

Distribution of MUC1 in the normal human oral cavity is localized to the ducts of minor salivary glands

The change in expression of MUC1 from health to disease forms the basis of its use as a potential disease marker. Previous attempts at isolating MUC1 from normal, healthy human oral mucosa have, however, drawn conflicting conclusions as to its presence. Furthermore, when MUC1 was detected in the oral glycocalyx, it was not clear which cells were synthesising it. We examined human oral glycocalyx using pooled buccal smears from 50 normal individuals. Following isopycnic density centrifugation and membrane extraction with octyl glucoside and saponin, MUC1 was detected with the polyclonal antibody CT1. Immunohistochemistry using antibodies CT1 and BC2 was performed on sections from eight labial, seven palatal, four buccal, three retromolar pad, three dorsum of tongue and two ventral surface of tongue biopsies. In-situ hybridisation using MUC1 and cytoplasmic tail oligoprobes on sections from four palatal, seven labial and two retromolar pad biopsies was also carried out. MUC1 mRNA could only be detected in the minor salivary mucous glands. MUC1 has already been identified in the ducts of normal parotid and submandibular gland, and our findings demonstrate a similar distribution in minor salivary glands. We conclude that when present in the normal oral glycocalyx, the only oral source of MUC1 is from cell membranes of the minor salivary glands.

An application of the thresholds of change model to the analysis of mental health data

The threshold of change model (TCM) is a statistical technique for analyzing ordered stages of change variables. TCM focuses on the thresholds that separate the ordered stages, and the effects of explanatory variables are evaluated in terms of raising or lowering the thresholds. TCM also allows the explanatory variables to exert differential influence on each threshold. In this paper, we use TCM to analyze the data from a clinical trial that compared assertive community treatment (ACT) with standard case management (SCM) for patients with co-occurring severe mental illness and substance use disorder. Endpoint data (36-month follow up) were used for this analysis. The response variable is the recoded Substance Abuse Treatment Scale with three ordered levels (engagement/persuasion, active treatment, and recovery/relapse prevention), and hence two thresholds. The explanatory variables are gender and group (ACT vs. SCM). The results indicate that gender exerts constant and significant effects on both thresholds. The group effect is somewhat mixed: ACT lowers the first threshold (active treatment), but raises the second threshold (recovery/relapse prevention).

Microsatellite instability in squamous cell carcinoma of head and neck from the Indian patient population

Genomic instability in simple repeated sequences has been observed in several human cancers. We have analyzed 50 squamous cell carcinomas of the head and neck (SCCHN) and 5 pre-malignant severe dysplastic tissues from Indian patient populations for microsatellite instability in 18 different loci spread over eight different chromosomes. Among the tumors analyzed, 45% exhibited instability at two or more loci, and 15% exhibited instability at 40% of the markers tested. Similar analysis of SCCHN tumors from other populations (British, American and French) showed much less frequency of instability. SCCHN tumors in the present study did not show any instability in the mononucleotide repeat sequences. There is also a clear distinction in the nature of the instability in these tumors in comparison with colorectal tumors. These results suggest that the underlying mechanism generating this type of instability is different from those reported for colorectal tumors.

Functional domains of yeast plasmid-encoded Rep proteins

Both of the Saccharomyces cerevisiae 2 microm circle-encoded Rep1 and Rep2 proteins are required for efficient distribution of the plasmid to daughter cells during cellular division. In this study two-hybrid and in vitro protein interaction assays demonstrate that the first 129 amino acids of Rep1 are sufficient for self-association and for interaction with Rep2. Deletion of the first 76 amino acids of Rep1 abolished the Rep1-Rep2 interaction but still allowed some self-association, suggesting that different but overlapping domains specify these interactions. Amino- or carboxy-terminally truncated Rep1 fusion proteins were unable to complement defective segregation of a 2 microm-based stability vector with rep1 deleted, supporting the idea of the requirement of Rep protein interaction for plasmid segregation but indicating a separate required function for the carboxy-terminal portion of Rep1. The results of in vitro baiting assays suggest that Rep2 contains two nonoverlapping domains, both of which are capable of mediating Rep2 self-association. The amino-terminal domain interacts with Rep1, while the carboxy-terminal domain was shown by Southwestern analysis to have DNA-binding activity. The overlapping Rep1 and Rep2 interaction domains in Rep1, and the ability of Rep2 to interact with Rep1, Rep2, and DNA, suggest a model in which the Rep proteins polymerize along the 2 microm circle plasmid stability locus, forming a structure that mediates plasmid segregation. In this model, competition between Rep1 and Rep2 for association with Rep1 determines the formation or disassembly of the segregation complex.

Modulation of DMBA induced genotoxicity in bone marrow by quercetin during skin carcinogenesis

Effect of quercetin was studied on DMBA induced skin carcinogenesis in young adult Swiss albino mice. Quercetin was administered continuously with the diet (2%) for four weeks and chromosomal aberration, a predictor of future cancer risk, studied in the bone marrow cells at different time intervals. Significant reduction of chromosomal aberration was observed in bone marrow after four weeks (P< 0.02). The reduction was first evident after 96 hrs though it was not significant at this stage. Significant decrease occurred from the 21st day onward when quercetin was given in concomitance with 7,12-dimethylbenz[a]anthracene (DMBA) indicating a definite protective effect of quercetin on chromosomal aberration.

The relationship of aging and dysthymia in primary care

The authors compared symptomatic and functional characteristics between older (age > or =60; n=91) and younger (age 18-59; n=125) primary care patients with dysthymia. Three of six significantly different depression symptoms were of moderate-to-large effect size, with the older group having a lower proportion reporting the symptom. The older group had a worse physical health function score but a better mental health function score. There appears to be a core of symptoms and functional impairment that generalizes across the age span. There are also significant age differences. Growing older appears to have an impact on the nature of what it means to have dysthymia.

Mechanism of neurofibrillary degeneration and pharmacologic therapeutic approach

Neurofibrillary degeneration is a key histopathological brain lesion of Alzheimer disease (AD) and related neurodegenerative disorders such as frontotemporal dementia and Parkinsonism linked to chromosome 17 (FTDP-17), commonly referred to as tauopathies. Microtubule associated protein (MAP) tau, which is a major MAP of a normal mature neuron is abnormally hyperphosphorylated in tauopathies and is the major protein subunit of paired helical filaments (PHF)/straight filaments (SF) which accumulate in the soma (as neurofibrillary tangles) and dystrophic neurites (as neuropil threads and as dystrophic neurites surrounding the beta-amyloid core in neuritic plaques in AD) of the affected neurons. Unlike normal tau which stimulates assembly and stabilizes microtubules, the abnormally hyperphosphorylated tau inhibits assembly and disrupts microtubules. The abnormally hyperphosphorylated tau competes with tubulin/microtubules in associating with normal tau, MAP1 and MAP2. This sequestration of normal MAPs by the abnormal tau results in the breakdown of the microtubules. The association of the abnormal tau with normal tau and not with MAP1 or MAP2 results in the formation of tangles of tau filaments. All these toxic properties of the abnormally hyperphosphorylated tau are eliminated by its enzymatic dephosphorylation. Activities of phosphoseryl/phosphothreonyl protein phosphatases (PP)-2A and PP-1 which can dephosphorylate the abnormal tau to a normal-like state are compromised in AD brain. Dephosphorylation by PP-2A and PP-2B and to a lesser extent by PP-1 restores the normal microtubule assembly promoting activity in AD P-tau in vitro. Neurofibrillary tangles of PHF isolated from AD brain are also dissociated on in vitro dephosphorylation with PP-2A, and the tau released by this treatment can stimulate microtubule assembly. Thus, it appears that the abnormal hyperphosphorylation of tau leads to neurodegeneration through breakdown of the microtubule network and that the abnormal tau on association with normal tau forms neurofibrillary tangles of tau filaments i.e. PHF/SF. Increase in tau phosphatase activity is a promising approach to inhibit neurofibrillary degeneration and thereby the diseases characterized by this lesion.

Family treatment and medication dosage reduction in schizophrenia: effects on patient social functioning, family attitudes, and burden

The effects of 2 family intervention programs (supportive family management [SFM], including monthly support groups for 2 years; or applied family management [AFM], including 1 year of behavioral family therapy plus support groups for 2 years), and 3 different neuroleptic dosage strategies (standard, low, targeted) on social functioning of patients with schizophrenia. their relatives' attitudes, and family burden were examined. AFM was associated with lower rejecting attitudes by relatives toward patients and less friction in the family perceived by patients. Patients in both AFM and SFM improved in social functioning but did not differ, whereas family burden was unchanged. Medication strategy had few effects, nor did it interact with family intervention. The addition of time-limited behavioral family therapy to monthly support groups improved family atmosphere, but did not influence patient social functioning or family burden.

Engineering aspects of enzymatic signal transduction: photoreceptors in the retina

Identifying the basic module of enzymatic amplification as an irreversible cycle of messenger activation/deactivation by a "push-pull" pair of opposing enzymes, we analyze it in terms of gain, bandwidth, noise, and power consumption. The enzymatic signal transduction cascade is viewed as an information channel, the design of which is governed by the statistical properties of the input and the noise and dynamic range constraints of the output. With the example of vertebrate phototransduction cascade we demonstrate that all of the relevant engineering parameters are controlled by enzyme concentrations and, from functional considerations, derive bounds on the required protein numbers. Conversely, the ability of enzymatic networks to change their response characteristics by varying only the abundance of different enzymes illustrates how functional diversity may be built from nearly conserved molecular components.

Palatogenesis and potential mechanisms for clefting

This review concentrates on mechanisms of palatogenesis. This includes theories of shelf elevation, the role of matrix and identification of molecules and growth factors, which have key roles. The areas where failure to develop could potentially lead to clefting are highlighted. A key part of shelf fusion is the breakdown of the medial edge epithelium, a process that is probably dependent on enzymes involved in matrix turnover. There is good evidence that the matrix metalloproteinases may provide a common link to the multiple genetic and environmental factors that are known to cause clefting.

Influences of graded dose of melatonin on the levels of blood glucose and adrenal catecholamines in male roseringed parakeets (Psittacula krameri ) under different photoperiods

Effects of daily evening (just before the onset of darkness in a 24 h light dark cycle) administration of graded doses (25, 50, or 100 microg/100 g body wt./day for 30 days) of melatonin on the concentrations of blood glucose and adrenal catecholamines were studied in sexually active male roseringed parakeets under natural (NP; approximately 12L: 12D) and artificial long (LP; 16L: 8D) and short (SP; 8L: 16D) photoperiods. Blood samples and adrenal glands were collected from each bird during the mid-day on the following day of the last treatment. The concentrations of glucose in blood and epinephrine (E) and norepinephrine (NE) in the adrenals were measured. The results of the study indicated that exogenous melatonin induces hypo- or hyperglycemia depending on the dose of hormone administered as well as to the length of photoperiod to which birds were exposed. The levels of E and NE in the adrenals were shown also to vary in relation to photoperiod and the dose of melatonin administered. But the nature of the influence of melatonin becomes different under altered photoperiodic conditions. It appears that short photoperiods are more effective than long photoperiods as a modulator of glycemic and adrenal catecholaminergic responses to exogenous melatonin. A statistically significant correlation between the levels of blood glucose and that of E and NE in the adrenals was found in the control birds, but not in the melatonin treated birds. The results suggested that the responses of blood glucose and adrenal catecholamines to the treatment with melatonin in the roseringed parakeets may not be dependent on each other.