Molecular insights into Pashmina fiber production: comparative skin transcriptomic analysis of Changthangi goats and sheep

Ladakh, one of the highest inhabited regions globally, hosts the unique Changthangi goat, renowned for producing Pashmina, the world's most luxurious natural fiber. In comparison, the fiber derived from Changthangi sheep is considered next only to Pashmina. This research endeavors to compare the skin transcriptome profiles of Changthangi goats and Changthangi sheep, aiming to discern the molecular determinants behind the recognition of Changthangi goats as the source of Pashmina. Drawing upon previously conducted studies, a collective of 225 genes correlated with fiber characteristics were extracted from the differentially expressed genes noticed between the two species (p-value of ≤ 0.05 and a log2 fold change of ≥ 1.5). These genes were analyzed using DAVID software to understand their biological functions and to identify enriched KEGG and Reactome pathways. The protein-protein interaction networks were constructed using Cytoscape, cytoHubba, and STRING to focus on key genes and infer their biological significance. Comparative transcriptome analysis revealed significantly higher expression of genes involved in signaling pathways like Wnt, MAPK, PI3K-Akt, Hedgehog, associated with fiber development and quality in Changthangi goats. These pathways play crucial roles in hair follicle (HF) formation, maintenance of epidermal stem cells, and fiber characteristics. Findings also highlight the enrichment of cell adhesion molecules and ECM-receptor interaction, emphasizing their roles in HF structure, growth, and signaling. This investigation offers an in-depth understanding of the molecular intricacies governing Pashmina production in Changthangi goats, providing valuable insights into their unique genetic makeup and underlying mechanisms influencing the exceptional quality of Pashmina fibers.

Identification and validation of stable reference genes for expression profiling of target genes in diverse ovine tissues

Quantitative PCR (qPCR) is a widely-used technique for quantifying the expression of target genes across various tissues, as well as under different pathological and physiological conditions. One of the challenges associated with this method is the need to identify optimal reference genes (RGs) that maintain consistent expression levels under diverse experimental settings, thereby ensuring accurate biological interpretation. In this study, we conducted a thorough analysis of 18 candidate RGs (ACTB, BACH1, B2M, GAPDH, HMBS, HPRT1, PGK1, PPIA, PPIB, RPLP0, RPL19, RPS9, RPS15, RPS28, SDHA, TBP, UXT, and YWHAZ) across 10 ovine tissues (muscle, skin, kidney, liver, intestine, rumen, lung, testis, heart, and spleen) obtained from five individual sheep. We aimed to identify genes with stable expression across these tissues. A literature-based survey helped us shortlist candidate genes representing various functional classes from multiple livestock species. We employed four algorithms: geNorm, NormFinder, BestKeeper, and Delta Ct (ΔCt), to rank these genes based on their stability. A consistent trend in the rankings was observed across these different algorithms. RefFinder was then used for a comprehensive ranking, integrating the outputs from the various methods. ACTB, PPIB, BACH1, and B2M emerged as the most stable RGs, while RPS9, RPS15, and PGK1 displayed variable expression. We validated our findings through qPCR analysis of four target genes (ACTN2, CRYAB, DLK1, and TRIM54) in the skin samples from two different sheep breeds. Based on these results, we recommend ACTB, PPIB, BACH1, and B2M as reliable internal control genes for qPCR experiments involving diverse ovine tissues.

Comprehensive evaluation and validation of optimal reference genes for normalization of qPCR data in different caprine tissues

BACKGROUND

Quantitative real-time PCR (qPCR) is a highly reliable method for validating gene expression data in molecular studies due to its sensitivity, specificity, and efficiency. To ensure accurate qPCR results, it's essential to normalize the expression data using stable reference genes.

METHODS

This study aimed to identify suitable reference genes for qPCR studies in goats by evaluating 18 candidate reference genes (ACTB, BACH1, B2M, GAPDH, HMBS, HPRT1, PGK1, PPIA, PPIB, RPLP0, RPL19, RPS9, RPS15, RPS28, SDHA, TBP, UXT, and YWHAZ) in 10 different caprine tissues (heart, intestine, kidney, liver, lung, muscle, rumen, skin, spleen, and testis). An integrated tool called RefFinder, which incorporates various algorithms like NormFinder, GeNorm, BestKeeper, and ΔCt, was used to assess the stability of expression among these genes.

RESULTS

After thorough analysis, ACTB, PPIB, and B2M emerged as the most stable reference genes, while RPL19, RPS15, and RPS9 were found to be the least stable. The suitability of the selected internal control genes was further validated through target gene analysis, confirming their efficacy in ensuring accurate gene expression profiling in goats.

CONCLUSION

The study determined that the geometric average of ACTB, PPIB, and B2M creates an appropriate normalization factor for gene expression studies in goat tissues.

Genetic insights into fiber quality, coat color and adaptation in Changthangi and Muzzafarnagri sheep: A comparative skin transcriptome analysis

Changthangi sheep, which inhabit the high-altitude regions of Ladakh, are known for their fine fiber production and are characterized by grey skin and either black or white coats. In contrast, Muzzafarnagri sheep from the plains of Uttar Pradesh produce coarse wool and have white skin and coats. We conducted comparative global gene expression profiling on four biological replicates of skin from each breed. Notably, our analysis identified 149 up-regulated genes and 2,139 down-regulated genes in Changthangi sheep compared to Muzzafarnagri sheep, with a p-adjusted value (padj) of ≤0.05 and a Log2 fold change of ≥1.5. Gene Ontology analysis of the up-regulated genes revealed an enrichment of terms related to melanin biosynthesis and developmental pigmentation. Additionally, enriched KEGG pathways included tyrosine metabolism and metabolic pathways. Among the melanogenesis-related genes that exhibited higher expression in Changthangi sheep were TYR, TYRP1, DCT, SLC45A2, PMEL, MLANA, and OCA2. These findings confirm melanin's role in both the animals' black coat color and UV protection at high-altitude. Furthermore, we observed more pronounced expression of genes related to fiber quality, namely KRTAP6, KRTAP7, KRTAP13, and KRTAP2, in the fine wool-producing sheep from Ladakh. The results of the RNA sequencing were validated using real-time PCR on 10 genes governing fiber quality and coat color, with ACTB and PPIB serving as reference genes. In conclusion, our comparative skin transcriptome analysis of Changthangi and Muzzafarnagri sheep sheds light on the genetic differences associated with distinct phenotypic traits and environmental adaptability, offering valuable insights into the underlying mechanisms.

Advances in genomics for diversity studies and trait improvement in temperate fruit and nut crops under changing climatic scenarios

Genetic improvement of temperate fruit and nut crops through conventional breeding methods is not sufficient alone due to its extreme time-consuming, cost-intensive, and hard-to-handle approach. Again, few other constraints that are associated with these species, viz., their long juvenile period, high heterozygosity, sterility, presence of sexual incompatibility, polyploidy, etc., make their selection and improvement process more complicated. Therefore, to promote precise and accurate selection of plants based on their genotypes, supplement of advanced biotechnological tools, viz., molecular marker approaches along with traditional breeding methods, is highly required in these species. Different markers, especially the molecular ones, enable direct selection of genomic regions governing the trait of interest such as high quality, yield, and resistance to abiotic and biotic stresses instead of the trait itself, thus saving the overall time and space and helping screen fruit quality and other related desired traits at early stages. The availability of molecular markers like SNP (single-nucleotide polymorphism), DArT (Diversity Arrays Technology) markers, and dense molecular genetic maps in crop plants, including fruit and nut crops, led to a revelation of facts from genetic markers, thus assisting in precise line selection. This review highlighted several aspects of the molecular marker approach that opens up tremendous possibilities to reveal valuable information about genetic diversity and phylogeny to boost the efficacy of selection in temperate fruit crops through genome sequencing and thus cultivar improvement with respect to adaptability and biotic and abiotic stress resistance in temperate fruit and nut species.

Structural changes in trypsin induced by the bile salts: An effect of amphiphile hydrophobicity

The present study reports the multi-technique results of the interaction of a series of bile salts, sodium cholate (NaC), sodium taurocholate (NaTC), sodium deoxycholate (NaDC), and sodium taurodeoxycholate (NaTDC) with trypsin under the experimental conditions of 25 °C and pH 7.0. The interactions between trypsin and the bile salts were characterized by the surface tension measurements and various spectroscopic techniques like UV-Visible absorption, steady-state fluorescence, and circular dichroism. The results of surface tension measurements reveal a strong interaction of trypsin (50 μM) with the increasing concentration of bile salts, being higher with the bile salt of greater hydrophobicity. The critical aggregation concentration of bile salts in the presence of trypsin (C₁) showed that the bile salts interact strongly with the trypsin in the order of NaTDC > NaDC > NaTC > NaC. UV-visible, steady-state fluorescence, and circular dichroism spectroscopic results confirmed significant unfolding of trypsin due to its interaction with the bile salts, the extent of which followed the same sequence as observed in the surface tension results. It could be concluded that the hydrophobic bile salts that show lower C₁ values and have less delocalized charge, are more effective in unfolding the trypsin. The study would help understand the hydrophobicity-driven unfolding of proteins aided by biological surfactants like bile salts and help devise efficient proteolytic enzyme-based detergent formulations and understand the role of such amphiphiles as antimicrobial agents.

Management of Pneumonia and Blood Stream Infections with New Antibiotic Adjuvant Entity (Ceftriaxone + Sulbactam + Disodium Edetate)- A Novel Way to Spare Carbapenems

INTRODUCTION

Nosocomial infections have been considered as a major health problem causing incremental morbidity, mortality and costs of therapy.

AIM

This retrospective study was initiated with aim to analyse the comparative efficacy of a novel Antibiotic Adjuvant Entity (AAE), a combination of ceftriaxone + sulbactam + disodium edetate and meropenem in combination with colistin, for the management of Multi Drug Resistant (MDR) nosocomial Gram-negative bacterial infections.

MATERIALS AND METHODS

Case history sheets of patients with documented MDR nosocomial Gram-negative infections who received either AAE or meropenem in combination with colistin for management of infections over a period of 3 years (November 2012 - October 2015) were included in the study. Data related to clinical management, demographics, vital signs and laboratory parameters along with prior antibiotic therapy, dose and clinical outcomes were evaluated thoroughly to analyse the clinical benefits of this new AAE+ colistin therapy for management of MDR nosocomial infections.

RESULTS

Out of 115 patients short listed for the study, 52 patients had received AAE + colistin therapy and 63 patients have received meropenem + colistin. AAE + colistin therapy resulted in significantly higher efficacy (86.53%) as compared to meropenem + colistin (63.49%). A rising trend in clinical cure rates was observed in AAE based combination therapy in contrast to the decreasing trend in meropenem based combination therapy. A progressive decline in clinical cure rates was observed in meropenem treated group over a period of 3 years due to rising carbapenemases and multiple resistance by pathogens, where as AAE maintained the same efficacy.

CONCLUSION

The AAE + colistin therapy has shown better bacteriological and clinical efficacy as compared to meropenem + colistin in the management of various nosocomial MDR Gram-negative infections. A significant number of meropenem failure patients responded to the AAE therapy highlighting the new hope to spare carbapenems.

Identifying factors affecting age at first semen freezing and age at first semen use in Sahiwal bulls

Aim:

The objective of the study was to evaluate the effects of non-genetic factors on reproduction traits viz. age at first semen freezing and age at first semen use of breeding bulls in Sahiwal bulls by fitting least-squares analysis.

Materials and Methods:

The information on reproduction traits of 43 Sahiwal breeding bulls belonging to 8 sets of Sahiwal breeding program at Indian Council of Agricultural Research-National Dairy Research Institute (ICAR-NDRI), Karnal (Haryana), India during 27 years (1987-2013) were analyzed using fixed linear model. The information was collected from AI records, reproduction sheets, and bull AI register maintained at different sections of Institute viz. record room of Dairy Cattle Breeding Division (DCB), Cattle Yard, Artificial Breeding Research Centre, ICAR-NDRI, Karnal.

Results:

The average age at first semen freezing and age at first semen use of Sahiwal breeding bulls was estimated as 3.17±0.01 years and 5.35±0.01 years, with the coefficient of variation 18.93% and 20%, respectively. The overall least-squares mean for age at first semen freezing and age at first semen use was estimated as 3.14±0.09 years and 5.25±0.02 years, respectively, in Sahiwal breeding bulls. Period of freezing/use had significant effects on reproductive traits (p<0.01). Season had no significant effect on any of the traits considered in this study.

Conclusion:

It can be concluded that management inputs such as nutrition, breeding, and optimum environment should be taken care of to optimize age at first semen freezing and age at first semen use for better utilization of superior germplasm.

Optimizing age of bull at first use in relation to fertility of Murrah breeding bulls

Aim:

The aim of the present investigation was to optimize the age at first use (AAFU) of semen of Murrah breeding bulls, which will help in early selection of bulls under progeny testing program for improving the reproductive performance in the herd.

Materials and Methods:

The data on AAFU, conception rate based on first A.I. (CRFAI), overall conception rate (OCR), and birth weight (B.WT) of 57 Murrah bulls during 1993-2014 at NDRI center pertaining to 14 sets of Network Project on Buffalo Improvement at ICAR-National Dairy Research Institute, Karnal, Haryana, India were adjusted for significant environmental influences and subsequently analyzed. Simple and multiple regression models were used for prediction of CRFAI and OCR of Murrah breeding bulls. Comparative evaluation of three developed models (I-III) showed that Model III, having AAFU and B.WT, fulfill the accuracy of model as revealed by high coefficient of determination, low mean sum of squares due to error, low conceptual predictive value, and low Bayesian information criterion.

Results:

The results revealed that the average predicted CRFAI was highest (39.95%) at <3.5 years and lowest (34.87%) at >4.5 years of age at first A.I/use. Similarly, average predicted OCR was highest (41.05%) at <3.5 years and lowest (39.42%) at >4.5 years of age at first A.I/use of Murrah bulls.

Conclusion:

In organized herd under progeny testing program, Murrah bulls should be used at young age, i.e. prior to 3.5 years, which is expected to result in 5.08% better CRFAI and 1.63% better OCR in comparison to Murrah bulls used after 4.5 years of age.

Diarrhoeagenic Escherichia coli and salmonellae in calves and lambs in Kashmir absence, prevalence and antibiogram

Polymerase chain reaction assays and culture were used to investigate 728 faecal samples from 404 calves (286 diarrhoeic, 118 healthy) and 324 lambs (230 diarrhoeic, 94 healthy) in Kashmir, India, for the presence of enterotoxigenic Escherichia coli (ETEC), enteroaggregative E. coli (EAEC), diffusely adherent E. coli (DAEC) and salmonellae. Antimicrobial sensitivity patterns were also investigated. In total, 23 ETEC isolates were obtained from the diarrhoeic calves and 12 from diarrhoeic lambs. Most (74%) of the isolates from calves harboured the gene encoding heat-labile enterotoxin I, whereas 75% of the isolates from lambs possessed only the gene encoding for heat-stable enterotoxin a. The ETEC isolates belonged to 20 serogroups, among which serogroups O15 (five isolates) and O8 (four isolates) were the most frequent. Salmonella Typhimurium or S. Enteritidis was identified in three samples from diarrhoeic lambs. The ETEC isolates and the salmonellae showed multidrug resistance. No EAEC or DAEC was detected in any of the samples.

Effects of surfactant micelles on solubilization and DPPH radical scavenging activity of Rutin

The interaction of the antioxidant Rutin with the radical DPPH (2,2-diphenyl-1-picrylhydrazyl) in presence of cationic (CTAB, TTAB, DTAB), non-ionic (Brij78, Brij58, Brij35), anionic (SDS) and mixed surfactant systems (CTAB-Brij58, DTAB-Brij35, SDS-Brij35) has been followed by spectrophotometric and tensiometric methods to evaluate the DPPH radical scavenging activity (RSA) of Rutin in these model self-assembled structures. The results show that the solubilization capacity of various single surfactant systems for both DPPH as well as Rutin followed the order cationics > non-ionics > anionic. The radical scavenging activity of Rutin in the solubilized form was higher within ionic micelles than in non-ionic micelles. However, the antioxidant exhibited enhanced activity for the radical in mixed cationic-non-ionic micelles compared with any of the single component micelles. In contrast, anionic-non-ionic mixed micelles modulated the activity of Rutin in-between that seen for pure anionic and non-ionic micelles only.

Isolation of atypical enteropathogenic Escherichia coli and Shiga toxin 1 and 2f-producing Escherichia coli from avian species in India

AIMS

To study the prevalence and characterize atypical enteropathogenic Escherichia coli (EPEC) and Shiga toxin producing E. coli (STEC) in avian species in India.

METHODS AND RESULTS

Two hundred and twelve faecal samples collected from 62 chickens, 50 ducks and 100 pigeons were investigated for the presence of stx(1), stx(2), eae and ehxA virulence genes by multiplex PCR. In all, 42 E. coli isolates (25 chicken, 2 duck and 15 pigeon) possessed at least one virulence gene. Out of these, nine (4.24%) isolates were STEC and 33 (15.56%) were EPEC. All isolates from duck and chicken were EPEC while among 15 pigeon isolates nine (60%) were STEC and six (40%) were EPEC. Among the STEC isolates four each carried stx(1) or stx(2) and one possessed both stx(1) and stx(2). Subtype analysis of stx revealed the presence of stx(2f) in four STEC isolates. None of the STEC isolates carried stx(1c), stx(2c), stx(2d) or stx(2e). Isolates carrying stx(2f) demonstrated vero cell toxicity. One each belonged to serogroup O17 and O78, while one was rough and the other untypeable. All EPEC isolates were atypical as they lacked bfpA. This appears to be the first report of detection of stx(2f) from India.

CONCLUSIONS

The study established the presence of stx(1) and stx(2f) containing E. coli in pigeons and atypical EPEC in poultry in India. Pigeons might serve as vectors for transmission of STEC to environment and humans.

SIGNIFICANCE AND IMPACT OF THE STUDY

Taking into account the close contact between fanciers and pigeons, these findings warrant a more critical appraisal of these zoonotic pathogens in pigeons and humans.

Hantavirus N protein exhibits genus-specific recognition of the viral RNA panhandle

A key genomic characteristic that helps define Hantavirus as a genus of the family Bunyaviridae is the presence of distinctive terminal complementary nucleotides that promote the folding of the viral genomic segments into "panhandle" hairpin structures. The hantavirus nucleocapsid protein (N protein), which is encoded by the smallest of the three negative-sense genomic RNA segments, undergoes in vivo and in vitro trimerization. Trimeric hantavirus N protein specifically recognizes the panhandle structure formed by complementary base sequence of 5' and 3' ends of viral genomic RNA. N protein trimers from the Andes, Puumala, Prospect Hill, Seoul, and Sin Nombre viruses recognize their individual homologous panhandles as well as other hantavirus panhandles with high affinity. In contrast, these hantavirus N proteins bind with markedly reduced affinity to the panhandles from the genera Bunyavirus, Tospovirus, and Phlebovirus or Nairovirus. Interactions between most hantavirus N and heterologous hantavirus viral RNA panhandles are mediated by the nine terminal conserved nucleotides of the panhandle, whereas Sin Nombre virus N requires the first 23 nucleotides for high-affinity binding. Trimeric hantavirus N complexes undergo a prominent conformational change while interacting with panhandles from members of the genus Hantavirus but not while interacting with panhandles from viruses of other genera of the family Bunyaviridae. These data indicate that high-affinity interactions between trimeric N and hantavirus panhandles are conserved within the genus Hantavirus.

Characterization of the RNA chaperone activity of hantavirus nucleocapsid protein

Hantaviruses are tripartite negative-sense RNA viruses and members of the Bunyaviridae family. The nucleocapsid (N) protein, encoded by the smallest of the three genome segments (S), has nonspecific RNA chaperone activity. This activity results in transient dissociation of misfolded RNA structures, may be required for facilitating correct higher-order RNA structure, and may function in viral genome replication. We carried out a series of experiments to further characterize the ability of N to dissociate RNA duplexes. As might be expected, N dissociated RNA duplexes but not DNA duplexes or RNA-DNA heteroduplexes. The RNA-destabilizing activity of N is ATP independent, has a pH optimum of 7.5, and has an Mg(2+) concentration optimum of 1 to 2 mM. N protein is unable to unwind the RNA duplexes that are completely double stranded. However, in the presence of an adjoining single-stranded region, helix unwinding takes place in the 3'-to-5' direction through an unknown mechanism. The N protein trimer specifically recognizes and unwinds the terminal panhandle structure in the viral RNA and remains associated with unwound 5' terminus. We suggest that hantaviral nucleocapsid protein has an active role in hantaviral replication by working cooperatively with viral RNA polymerase. After specific recognition of the panhandle structure by N protein, the unwound 5' terminus likely remains transiently bound to N protein, creating an opportunity for the viral polymerase to initiate transcription at the accessible 3' terminus.

The hantavirus nucleocapsid protein recognizes specific features of the viral RNA panhandle and is altered in conformation upon RNA binding

Hantaviruses are tripartite negative-sense RNA viruses and members of the Bunyaviridae family. The nucleocapsid (N) protein is the principal structural component of the viral capsid. N forms a stable trimer that specifically recognizes the panhandle structure formed by the viral RNA termini. We used trimeric glutathione S-transferase (GST)-N protein and small RNA panhandles to examine the requirements for specific recognition by Sin Nombre hantavirus N. Trimeric GST-N recognizes the panhandles of the three viral RNAs (S, M, and L) with high affinity, whereas the corresponding plus-strand panhandles of the complementary RNA are recognized with lower affinity. Based on analysis of nucleotide substitutions that alter either the higher-order structure of the panhandle or the primary sequence of the panhandle, both secondary structure and primary sequence are necessary for stable interaction with N. A panhandle 23 nucleotides long is necessary and sufficient for high-affinity binding by N, and stoichiometry calculations indicate that a single N trimer interacts with a single panhandle. Surprisingly, displacement of the panhandle structure away from the terminus does not eliminate recognition by N. The binding of N to the panhandle is an entropy-driven process resulting in initial stable N-RNA interaction followed by a conformational change in N. Taken together, these data provide insight into the molecular events that take place during interaction of N with the panhandle and suggest that specific high-affinity interaction between an RNA binding domain of trimeric N and the panhandle is required for encapsidation of the three viral RNAs.

Trimeric hantavirus nucleocapsid protein binds specifically to the viral RNA panhandle

Hantaviruses are tripartite negative-sense RNA viruses and members of the Bunyaviridae family. The nucleocapsid (N) protein is encoded by the smallest of the three genome segments (S). N protein is the principal structural component of the viral capsid and is central to the hantavirus replication cycle. We examined intermolecular N-protein interaction and RNA binding by using bacterially expressed Sin Nombre virus N protein. N assembles into di- and trimeric forms. The mono- and dimeric forms exist transiently and assemble into a trimeric form. In contrast, the trimer is highly stable and does not efficiently disassemble into the mono- and dimeric forms. The purified N-protein trimer is able to discriminate between viral and nonviral RNA molecules and, interestingly, recognizes and binds with high affinity the panhandle structure composed of the 3' and 5' ends of the genomic RNA. In contrast, the mono- and dimeric forms of N bind RNA to form a complex that is semispecific and salt sensitive. We suggest that trimerization of N protein is a molecular switch to generate a protein complex that can discriminate between viral and nonviral RNA molecules during the early steps of the encapsidation process.

Association of the anticancer antibiotic chromomycin A(3) with the nucleosome: role of core histone tail domains in the binding process

The anticancer antibiotic chromomycin A(3) is a transcription inhibitor which forms two types of complexes with Mg(2+): complex I (1:1 in terms of chromomycin A(3)-Mg(2+)) and complex II (2:1 in terms of chromomycin A(3)-Mg(2+)). These complexes are the DNA-binding ligands. With the broad objective of elucidation of the mechanism for action of this group of transcription inhibitors in eukaryotic systems, we have studied the interaction of the antibiotic with nucleosome core particles under different conditions. We have demonstrated and characterized the role of core histone proteins, particularly the N-terminal tail domains, in the association of nucleosome with both complexes of chromomycin. From a scrutiny of the spectroscopic features of the two bound complexes and comparison of the binding and associated thermodynamic parameters, we have shown the following. Core histone(s) stand(s) in the way of access of the ligand(s) to nucleosomal DNA. N-Terminal intact and chopped core particles interact differentially with the same complex. The modes of interaction of the two complexes, I and II, with the same system are different. Tryptic removal of N-terminal tail domains of core histones enhances the binding potential and access of both complexes of chromomycin to the nucleosomal DNA. Agarose gel electrophoresis of an equilibrium mixture containing either complex I or complex II and a saturating concentration of the core particle has demonstrated that both complexes have a tendency to disrupt the nucleosome structure, leading to a release of nucleosomal DNA. Compared to the N-terminal intact nucleosome, the N-terminal chopped nucleosome is more susceptible to disruption. Therefore, we suggest from the above results that the N-terminal tail domains, which have an important role in eukaryotic gene expression, stand in the way of a free access of external agents such as anticancer drugs to the eukaryotic genome. The significance of the results to understand the molecular basis of the transcription inhibitory capacity of chromomycin is discussed.

Differential interactions of antitumor antibiotics chromomycin A(3) and mithramycin with d(TATGCATA)(2) in presence of Mg(2+)

The antitumor antibiotics chromomycin A(3) (CHR) and mithramycin (MTR) are known to inhibit macromolecular biosynthesis by reversibly binding to double stranded DNA with a GC base specificity via the minor groove in the presence of a divalent cation such as Mg(2+). Earlier reports from our laboratory showed that the antibiotics form two types of complexes with Mg(2+): complex I with 1:1 stoichiometry and complex II with 2:1 stoichiometry in terms of the antibiotic and Mg(2+). The binding potential of an octanucleotide, d(TATGCATA)(2), which contains one potential site of association with the above complexes of the two antibiotics, was examined using spectroscopic techniques such as absorption, fluorescence, and circular dichroism. We also evaluated thermodynamic parameters for the interaction. In spite of the presence of two structural moieties of the antibiotic in complex II, a major characteristic feature was the association of a single ligand molecule per molecule of octameric duplex in all cases. This indicated that the modes of association for the two types of complexes with the oligomeric DNA were different. The association was dependent on the nature of the antibiotics. Spectroscopic characterization along with analysis of binding and thermodynamic parameters showed that differences in the mode of recognition by complexes I and II of the antibiotics with polymeric DNA existed at the oligomeric level. Analysis of the thermodynamic parameters led us to propose a partial accommodation of the ligand in the groove without the displacement of bound water molecules and supported earlier results on the DNA structural transition from B --> A type geometry as an obligatory requirement for the accommodation of the bulkier complex II of the two drugs. The role of the carbohydrate moieties of the antibiotics in the DNA recognition process was indicated when we compared the DNA binding properties with the same type of Mg(2+) complex for the two antibiotics.

Interaction of mithramycin with chromatin

Mithramycin (MTR) is an anti-cancer antibiotic that blocks the macromolecular biosynthesis via reversible interaction with DNA template in the presence of bivalent metal ion such as Mg2+. In absence of DNA, mithramycin forms two types of complexes with Mg2+, complex I (with 1:1 stoichiometry in terms of MTR: Mg2+) and complex II (with 1:2 stoichiometry in terms of MTR: Mg2+). In an eukaryotic system, the drug would interact with chromatin, a protein-DNA complex. We have employed the spectroscopic techniques such as absorption and fluorescence to study the interaction of MTR: Mg2+ complexes with rat liver chromatin. In this report, we have shown that the two types of ligands have different binding potentials with the same chromatin. This supports our proposition that complexes I and II, are different molecular species. We have also shown that the histone protein(s) reduce the binding potential and the number of available sites for both ligands.

Interaction of antitumor drug, mithramycin, with chromatin

Mithramycin (MTR) is an anticancer drug that blocks macromolecular biosynthesis via reversible interaction with DNA in the presence of bivalent cation such as Mg2+. Mithramycin forms two types of complexes with Mg2+: complex I (1:1 in terms of MTR:Mg2+) and complex II (2:1 in terms of MTR:Mg2+). In vivo antibiotic would interact with chromatin, a protein-DNA complex. For the first time we have demonstrated and characterized the association of both complexes of MTR with chromatin and nucleosome core. From an evaluation and comparison of the binding and thermodynamic parameters and CD spectra of bound complexes, we have shown the following. Histone(s) stand in the say of the access of the ligand(s) to chromosomal DNA. Chromatin and core particle interact differentially with the same ligand. Mode of interaction of the two complexes, I and II, with the same system is different. Significance of these results to understand the transcription inhibitory property of the drug in eukaryotic chromosome is discussed.

Infant sleep position and SIDS: a hospital-based interventional study

CONTEXT

Avoidance of the prone sleeping position is considered an important factor contributing to the decline in the incidence of sudden infant death syndrome (SIDS).

OBJECTIVES

To determine infant sleep positioning practices and SIDS awareness before and after a hospital-based Back to Sleep campaign.

DESIGN

A questionnaire-based, descriptive, and cross-sectional before-after trial.

SETTING

The pediatric outpatient department of an inner-city hospital in Brooklyn, New York.

SUBJECTS

Two consecutive samples of 250 mothers of healthy infants younger than 6 months old born in and attending the outpatient clinics of the hospital before and after the intervention.

INTERVENTION AND MAIN OUTCOME MEASURES

Specific policies promoting Back to Sleep were established in our newborn nursery and outpatient department. Reduction in prone infant sleep positioning was the primary outcome measure. Increased parental SIDS awareness was a secondary outcome.

RESULTS

The proportion of infants sleeping prone was reduced significantly (from 27% to 18%) after the intervention (P < .005). Among the mothers who chose the prone sleeping position for their infants, 49.6% worried about choking. Older mothers (> 22 years) responded to the intervention by a 45.6% reduction in prone placement (P < .005) as opposed to a 11.4% reduction among younger mothers (< 22 years) (P = ns). Other factors contributing to reduced prone positioning included marriage (adjusted odds ratio [OR] 0.57; 95% confidence interval [CI] 0.93, 0.34) and breast feeding (adjusted OR 0.66; 95% CI 1.1, 0.4). SIDS awareness was 79.6% and 82.4% in the preintervention and postintervention groups, respectively (P = ns).

CONCLUSIONS

The Back to Sleep campaign was effective in our hospital setting. Our data indicate the need for special targeting of young, unmarried, and non-breast-feeding mothers. Fear of choking remains an important deterrent to proper infant sleep positioning.

Iron deficiency in 1- to 3-year-old children. A pediatric failure?

OBJECTIVE

To determine the prevalence of iron deficiency and iron deficiency anemia in children aged 1 to 3 years in an urban population.

DESIGN

Venous blood was measured for levels of hemoglobin, ferritin, free erythrocyte protoporphyrin, and lead in children seen for well-child visits. Children with histories of chronic illness, prematurity, blood dyscrasias, and acute illness were excluded.

SETTING

The private practice offices of 4 pediatricians in the New York City area.

PATIENTS

A consecutive sample of 504 children aged 1 to 3 years was included.

RESULTS

More than one third (35%) of the children demonstrated evidence of iron insufficiency; 7% were iron deficient without anemia, and 10% had iron deficiency anemia.

CONCLUSION

Because the association of iron deficiency anemia with mental and psychomotor impairment during the first 2 years of life no longer seems to be in doubt, the high prevalence of iron deficiency anemia found in the 1- to 2-year-old children in this study is disturbing. This suggests the need for greater efforts at the prevention of iron deficiency during the second year of life.

A new breakfast cereal containing guar gum reduces postprandial plasma glucose and insulin concentrations in normal-weight human subjects

A new guar-containing wheatflake product was developed to assess its effect on carbohydrate tolerance in normal-weight, healthy subjects. The extruded wheatflake breakfast cereals containing 0 (control) or approximately 90 g guar gum/kg DM were fed to ten fasting, normal-weight, healthy subjects using a repeated measures design. The meals were similar in energy (approximately 1.8 MJ), available carbohydrate (78 g), protein (15 g) and fat (5.4 g) content. The guar gum content of the test meals was 6.3 g. Venous blood samples were taken fasting and at 15, 30, 45, 60, 90, 120, 150 and 240 min after commencing each breakfast and analysed for plasma glucose, insulin and C-peptide. The guar wheatflake meal produced a significant main effect for glucose and insulin at 0-60 min and 0-240 min time intervals respectively, but not for the C-peptide levels compared with the control meal. Significant reductions in postprandial glucose and insulin responses were seen following the guar wheatflake meal compared with the control meal at 15 and 60 min (glucose) and 15, 60, 90 and 120 min (insulin). The 60 and 120 min areas under the curve for glucose and insulin were significantly reduced by the guar gum meal, as was the 240 min area under the curve for insulin. Thus, it can be concluded that the use of a severe method of heat extrusion to produce guar wheatflakes does not diminish the physiological activity of the guar gum.

Comparison of lipid-lowering effects of low-dose fluvastatin and conventional-dose gemfibrozil in patients with primary hypercholesterolemia

A total of 123 patients with primary hypercholesterolemia were randomized on a 2:1 ratio to receive either fluvastatin at 20 mg once daily at night (n = 82) or gemfibrozil at 600 mg twice daily (n = 41) in a double-blind, double-dummy comparison of the effects on plasma lipid parameters and tolerability over 8 weeks. All patients had either low-density lipoprotein cholesterol (LDL-C) concentrations > or = 160 mg/dL (4.1 mmol/L) in association with definite coronary artery disease (CAD) or > or = 2 risk factors, or LDL-C > or = 190 mg/dL (4.9 mmol/L) with no CAD and < 2 risk factors. All had triglyceride (TG) levels < or = 350 mg/dL (4.0 mmol/L). After 8 weeks of treatment, fluvastatin produced significant reductions from baseline of 17.4% (p < 0.001) in LDL-C, 13.2% (p < 0.001) in total cholesterol (TC), 13.8% (p < 0.001) in very low-density lipoprotein cholesterol (VLDL-C), and 6.4% (NS) in TG. High-density lipoprotein cholesterol (HDL-C) was increased by 5.6% (p < 0.001), and the ratio of LDL-C:HDL-C (Friedewald) was decreased by 21.2% (p < 0.001). Gemfibrozil reduced LDL-C by 15.8%, TC by 13.4%, VLDL-C by 32.2%, LDL-C:HDL-C by 24.8%, and TG by 34.2%, and increased HDL-C by 13.9% (all changes were statistically significant, p < 0.001) compared with baseline. Gemfibrozil produced significantly greater changes in VLDL-C (p < 0.01), HDL-C (p < 0.001), and TG (p < 0.001), but not in LDL-C: HDL-C, compared with fluvastatin. Both drugs significantly reduced apolipoprotein (apo) B and lipoparticles (Lp) E:B, and increased apo A-I but had divergent effects on LpA-I (increased with fluvastatin and reduced with gemfibrozil; p < 0.05). At the end of the study, 43.8% of fluvastatin patients and 45% of gemfibrozil patients achieved a reduction of > 20% in LDL-C levels. Normalization of LDL-C levels was achieved (according to European Atherosclerosis Society guidelines) by 13.4% of fluvastatin- and 14.6% of gemfibrozil-treated patients. Both drugs were well tolerated; adverse events occurred in 36.6% of fluvastatin recipients compared with 58.5% of patients taking gemfibrozil. No clinically notable elevations of aspartate or alanine aminotransferases, alkaline phosphatase, or creatine phosphokinase occurred. No patient developed new or worsening lens opacities associated with a reduction in optically corrected visual acuity. The most commonly reported adverse events were headache and gastrointestinal upset. There were no serious drug-related adverse events.

Effect of British-made videotapes on clinical performance of medical students in Pakistan

The efficacy of videotapes, recorded in Cardiff, in improving the clinical performance of final-year medical students in Abbottabad (Pakistan) was tested, by carrying out a structured, stepwise, clinical assessment before and after video teaching in 32 students. All students examined eight systems/subsystems at eight stations and spent 5 min with each patient, during which their performance was checked against structured check-lists by eight examiners. These students had not received any clinical instruction from a specialist rheumatologist, neurologist or endocrinologist during their clinical apprenticeship. Before the video teaching they performed poorly when examining the knee joint, motor system, hands and thyroid status, but when tested again 2 days after video teaching, there was a transformation in their clinical behaviour and their mean (s.d.) score improved from 40 (6.6 per cent) to 57.6 (9.4 per cent; P = 0.001). In contrast to their pre-video performance, they interacted well with the patients and examiners providing a running commentary of their findings, as demonstrated in the videotapes. Among the residual problems were a poor technique of testing tendon reflexes and percussion. All the examiners and 21 of 32 students thought that the structured examination was fairer than the conventional examination. Of the 32 students, 20 thought that video teaching was less effective than personal bedside teaching, while 12 students thought that video was structured better than bedside instruction. All students would welcome video teaching to supplement their existing teaching and would like the structured examination introduced to their curriculum. This study suggests that videotaped demonstrations can be used effectively in transmitting clinical skills to students not exposed to clinical teaching by specialists in various subjects.

Interaction of inhibitin with the human erythrocyte Na+(Li+)i/Nao+ exchanger

The kinetic interactions of inhibitin, a peptide isolated from cultured leukaemic promyelocytes, with erythrocyte Na+/Na+ and Na+/Li+ exchanges have been investigated. Inhibitin (1 microM) reduced the ouabain- and bumetanide-resistant sodium efflux and influx by equivalent amounts indicating an inhibitin-sensitive exchange component of 0.52 mmol/l per h. This value was not significantly different from that measured as the difference in sodium-rich (140 mM) and sodium-free media (0.49 mmol/l per h). Similarly, the inhibitin-sensitive lithium efflux was equivalent to the sodium/lithium countertransport component (0.36 vs. 0.34 mmol/l per h), indicating that both exchanges were mediated by the same transport process, which is inhibitin-sensitive. The dose-response curve revealed the presence of a single inhibitin binding site per exchanger with a Ki of 2.10(-7) M. In kinetic inhibition studies, inhibitin (0.1 microM) decreased the Vmax of ouabain- and bumetanide-resistant sodium efflux with no effect on the Km for external sodium, i.e., inhibitin displayed a non-competitive mechanism of action. These findings indicate that inhibitin interacts with the Na+(Li+)i/Nao+ exchanger at a site distinct from the sodium binding site.

Characterization of Na+ transport in normal human fibroblasts and neoplastic H.Ep.2 cells and the role of inhibitin

Na+ transport was characterized in normal human fibroblasts and neoplastic H.Ep.2 cells in order to investigate the role of the endogenous peptidic factor 'inhibitin' that is secreted by a variety of neoplastic cells (including H.Ep.2) and inhibits Na+/Na+ exchange in human erythrocytes. Although active (Na+,K+-ATPase mediated) Na+ fluxes were similar in the two cell types, H.Ep.2 cells maintained higher intracellular Na+ concentration (26 mM) compared to fibroblasts (12 mM). An analysis of passive Na+ fluxes showed a difference in the handling of Na+ via ouabain and bumetanide-insensitive transport between the two cell types: H.Ep.2 cells achieved net Na+ influx via an amiloride-sensitive pathway that was only demonstrated in fibroblasts when 10% fetal calf serum (FCS) was present. Kinetic studies were undertaken to investigate the interaction between Na+ flux via Na+/H+ and Na+/Na+ exchanges. For this purpose, an outwardly directed Na+ gradient was created by loading the cells with Na+ (Nai greater than 100 mM) to activate the reverse functioning of Na+/H+ exchange (i.e., Na+out H+in). The rates of ouabain- and bumetanide-insensitive Na+ efflux were measured over a range of extracellular Na+ concentrations (Na+o 14-140 mM). In the presence of 10% FCS, the two cell types showed different responses: in fibroblasts the Na+ efflux rate showed an inverse correlation with extracellular Na+ concentration, while H.Ep.2 cells significantly increased their rate of Na+ efflux as extracellular Na+ concentration increased. So although the thermodynamic force would direct net Na+ efflux when Na+i greater than Na+o, H.Ep.2 cells were under kinetic control to perform Na+/Na+ exchange. When exogenous inhibitin was tested on fibroblasts, the steady-state intracellular Na+ concentration increased from 14 to 19 mM (p less than 0.01). In Na+-loaded fibroblasts, serum-stimulated Na+ efflux was partially inhibitin sensitive and the maximal inhibitory effect was seen when extracellular Na+ concentration was 14 mM and presumably the Na+/H+ exchanger operating in the reverse mode. This study demonstrated that, in contrast to fibroblasts, H.Ep.2 cells have a modified Na+/H+ exchange system whereby it acts in the Na+in H+out mode without exogenous growth factor activation and resists functioning in the reversed mode. It is proposed that inhibitin is the endogenous modifier of this transport system in H.Ep.2 cells with the result that H.Ep.2 cells maintain a higher concentration of intracellular Na+ compared to fibroblasts.

The relationship of dietary salt and blood pressure in three farming communities in Kashmir

The relationship between salt intake and blood pressure was explored in three different areas of Northern Kashmir, where people consume large quantities of salt in tea. Six villages were selected from each area and all the available family members of every second or third house were studied. Food and salt were weighed and the intake of each family member was obtained from the amount consumed out of the total cooked. Complete data were available from 361 subjects (191 males, 170 females). There was no significant difference between the three areas as regards age, height, weight, salt intake and blood pressure. Their age ranged from 15 to 88 yrs (mean 44) and the daily salt intake ranged from 70 to 420 mmol (mean 169 mmol). No correlation was found between age and salt intake or weight but there was a significant correlation between age and systolic blood pressure (r = 0.296; P less than 0.01). Both the systolic and diastolic blood pressure correlated significantly with the salt intake with correlation coefficients of 0.385 and 0.318 respectively (P less than 0.001). Multiple regression analyses showed that the significant relationship between salt and blood pressure was unaltered by adjustment for age. Of the 361 subjects, 46 (12.7%) had a blood pressure of 160/95 mmHg or more. This study suggests a similar relationship between habitual salt intake and blood pressure in each of three different areas of Northern Kashmir.

Calcium retention and increased vascular reactivity caused by a hypothalamic sodium transport inhibitor

1. Using a previously established method of isolating an active-sodium-transport inhibitor (ASTI) from hypothalamic cell culture medium, the inhibitor was isolated and partially purified from sequential passages through Sephadex G-25 and h.p.l.c., and its effects on de-endothelialized rabbit aortic strips were investigated. 2. ASTI caused a cumulative concentration-dependent increase in tension which reversed slowly after wash, and the wash showed an identical effect on fresh strips. 3. Ouabain, used as a control, also caused a concentration-dependent increase in tension which reached a plateau at a concentration of 10 mmol/l. Both ouabain and ASTI caused a significant potentiation of the vasoconstrictor effect of noradrenaline at concentrations of 1 nmol/l-0.1 mmol/l. 4. Both ASTI and ouabain caused a significantly greater (P less than 0.01) calcium retention than control medium in aortic strips. 5. Incubation of ASTI with prolidase, chymotrypsin and carboxypeptidase A destroyed the vasoconstrictor effects as well as its inhibitory effects on sodium, potassium-dependent adenosine triphosphatase and sodium efflux from erythrocytes, but leucine aminopeptidase was ineffective. 6. These studies suggest that hypothalamic cells in culture release a peptidic inhibitor of active sodium transport which increases vascular reactivity, potentiates vasoconstrictor effects of noradrenaline and causes calcium retention.