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Biomedical subjects

G Robinson

Publications and source records attributed to G Robinson.

At least 19 recordsLinked to original sources
PubMed2026

Genome-targeted enrichment and sequencing of human-infecting Cryptosporidium spp.

Cryptosporidium spp. are parasites that cause severe illness in vulnerable human populations. Obtaining pure and sufficient Cryptosporidium DNA from clinical and environmental samples is a challenging task. Oocysts shed in available fecal samples can be limited in quantity, require purification (biased towards dominant strains), and yield limited DNA (&#x2009;<&#x2009;40 fg/oocyst). Here, we use updated genomic sequences from a broad diversity of Cryptosporidium species that have been found to infect humans (C. cuniculus, C. hominis, C. meleagridis, C. parvum, C. tyzzeri, and C. viatorum) to develop and validate a set of 100,000 RNA baits (CryptoCap_100k) with the aim of enriching Cryptosporidium DNA from varied samples. Compared to unenriched libraries, CryptoCap_100k increases the percentage of reads mapping to target genome sequences, increases the depth and breadth of genome coverage, and facilitates analyses of genetic variants in many samples, while decreasing overall costs.

Cryptosporidium↗
PubMed2025

GENOME TARGETED ENRICHMENT AND SEQUENCING OF HUMAN-INFECTING CRYPTOSPORIDIUM spp.

Cryptosporidium spp. are parasites that cause severe illness in vulnerable human populations. Obtaining pure and sufficient Cryptosporidium DNA from clinical and environmental samples is a challenging task. Oocysts shed in available fecal samples can be limited in quantity, require purification (biased towards dominant strains), and yield limited DNA (<40 fg/oocyst). Here, we use updated genomic sequences from a broad diversity of human-infecting Cryptosporidium species ( C. cuniculus , C. hominis , C. meleagridis , C. parvum , C. tyzzeri , and C. viatorum ) to develop and validate a set of 100,000 RNA baits (CryptoCap_100k) with the aim of enriching Cryptosporidium spp. DNA from varied samples. Compared to unenriched libraries, CryptoCap_100k increases the percentage of reads mapping to target genome sequences, increases the depth and breadth of genome coverage and the reliability of detecting species and mixed infections within a sample, and allows assessment of genetic variation via SNP calling, while decreasing costs.

Journal Article↗
PubMed2024

WHOLE GENOME TARGETED ENRICHMENT AND SEQUENCING OF HUMAN-INFECTING CRYPTOSPORIDIUM spp.

Cryptosporidium spp. are protozoan parasites that cause severe illness in vulnerable human populations. Obtaining pure Cryptosporidium DNA from clinical and environmental samples is challenging because the oocysts shed in contaminated feces are limited in quantity, difficult to purify efficiently, may derive from multiple species, and yield limited DNA (<40 fg/oocyst). Here, we develop and validate a set of 100,000 RNA baits (CryptoCap_100k) based on six human-infecting Cryptosporidium spp. (C. cuniculus, C. hominis, C. meleagridis, C. parvum, C. tyzzeri, and C. viatorum) to enrich Cryptosporidium spp. DNA from a wide array of samples. We demonstrate that CryptoCap_100k increases the percentage of reads mapping to target Cryptosporidium references in a wide variety of scenarios, increasing the depth and breadth of genome coverage, facilitating increased accuracy of detecting and analyzing species within a given sample, while simultaneously decreasing costs, thereby opening new opportunities to understand the complex biology of these important pathogens.

Journal Article↗
PubMed2024

Phylogenomic reconstruction of Cryptosporidium spp. captured directly from clinical samples reveals extensive genetic diversity.

Cryptosporidium is a leading cause of severe diarrhea and mortality in young children and infants in Africa and southern Asia. More than twenty Cryptosporidium species infect humans, of which C. parvum and C. hominis are the major agents causing moderate to severe diarrhea. Relatively few genetic markers are typically applied to genotype and/or diagnose Cryptosporidium. Most infections produce limited oocysts making it difficult to perform whole genome sequencing (WGS) directly from stool samples. Hence, there is an immediate need to apply WGS strategies to 1) develop high-resolution genetic markers to genotype these parasites more precisely, 2) to investigate endemic regions and detect the prevalence of different genotypes, and the role of mixed infections in generating genetic diversity, and 3) to investigate zoonotic transmission and evolution. To understand Cryptosporidium global population genetic structure, we applied Capture Enrichment Sequencing (CES-Seq) using 74,973 RNA-based 120 nucleotide baits that cover ~92% of the genome of C. parvum. CES-Seq is sensitive and successfully sequenced Cryptosporidium genomic DNA diluted up to 0.005% in human stool DNA. It also resolved mixed strain infections and captured new species of Cryptosporidium directly from clinical/field samples to promote genome-wide phylogenomic analyses and prospective GWAS studies.

Cryptosporidium↗
PubMed1992

Luteinizing hormone response to oxytocin is steroid-dependent.

Oxytocin-induced LH release from dispersed rat anterior pituitary cells in vitro was shown to be dependent on the steroidal environment. Preincubation of anterior pituitary cells with estradiol for 48 h enhanced the subsequent LH response to oxytocin (p less than 0.001). Maximal sensitization was observed with estradiol at 1 nM. Release of LH induced by oxytocin was inhibited in the presence of progesterone or to a greater extent in the presence of equimolar testosterone. Complete suppression of oxytocin-induced LH secretion occurred with 1 nM progesterone. Incubation of hemipituitaries with oxytocin revealed that the pituitary was sensitive in vitro to oxytocin at proestrus (p less than 0.05) but not at other stages of the cycle. The results indicate that there is altered sensitivity to oxytocin of the pituitary at different stages of the estrous cycle. Therefore activity of the neuropeptide in vivo might be modulated by steroids.

Animals↗
PubMed1992

Oxytocin stimulates LH production by the anterior pituitary gland of the rat.

Gonadotrophin-releasing activity of oxytocin has previously been demonstrated in vitro and in vivo. This study investigated whether oxytocin is also able to induce LH accumulation in pituitary cells. Following trypsin digestion and mechanical dispersion, pituitary cells from female rats were incubated with oxytocin (100 nmol/l) for 24 h. LH release stimulated by oxytocin increased (P less than 0.001) progressively during the incubation indicating a different secretory pattern from the more rapid but less sustained secretion stimulated by gonadotrophin-releasing hormone. Oxytocin also enhanced (P less than 0.01) total LH accumulation in the incubation system (released plus cell contents) which was apparent after 7-11 h of stimulation. The release of LH stimulated by oxytocin was reduced by the protein synthesis inhibitor cycloheximide (10 mumol/l). However, cycloheximide did not completely block oxytocin-stimulated LH release; there remained some LH release above that seen in nonstimulated controls (P less than 0.01) revealing the presence of a cycloheximide-resistant component in the release mechanism. Furthermore, accumulation of total LH in 24 h incubations was suppressed (P less than 0.01) by cycloheximide. The advancement in LH release which oxytocin has been shown to induce in vivo in pro-oestrous rats was accompanied by an early reduction of pituitary LH stores. However, the fall normally observed in LH content during the surge was markedly attenuated by the oxytocin treatment. Thus, loss of pituitary LH stores was less in oxytocin-treated rats than in saline-treated controls, even though net LH release into plasma was increased. Therefore, oxytocin stimulated the replenishment of LH stores.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Increased postnatal growth rates of offspring after antiestrogen treatment of rat dams during pregnancy.

The effects of administration of estradiol antiserum to pregnant rats on birth weight, subsequent growth velocity, carcass composition, and reproductive performance of their offspring were examined. Treated rats were injected i.p. with a potent antiestradiol serum on d 12 of gestation, whereas control rats received a similar injection of normal sheep serum. The pups from the treated rats were 12.2% heavier at birth than those from control rats (P less than .01) and had a greater postnatal growth rate (P less than .05). Chemical analysis of body composition at 56 d of age revealed that there was a tendency for female offspring from treated rats to exhibit carcass characteristics (such as increased percentage of body fat) that were more similar to those of normal male rats than to those of normal female rats. Neither onset of puberty nor reproductive performance was affected by the treatment. These results indicate that treatment of rats during pregnancy with antiestradiol may have potential as a technique for increasing postnatal growth rates.

Animals↗
PubMed1992

Procoagulant changes induced by oral contraceptives are balanced by an increased fibrinolytic tendency.

Oral contraceptives caused increased fibrinogen, FVII, FX, and fibrinolysis. The latter was associated with elevated FXII and PKK, while C1-INH was decreased, ATIII and alpha 2M were unchanged; it could not be accounted for by changes in t-PA, u-PA, PAI, plasminogen, alpha 2-AP, proteins C or S. HCII and alpha 1-PI were increased and may regulate the availability of thrombin and FXIa. The increased FXII/PKK dependent fibrinolytic potential and HCII may offset any increase in thrombin generation, while alpha 1-PI limits intrinsic coagulation.

Adult↗
PubMed1991

Educational activities on wards under 12 hour shifts.

Interest in 12 hour nursing shifts has renewed in response to demands for improved cost effectiveness in the NHS. But the effects of the shift on nursing education are unclear. A repeated measures study was conducted, using activity analysis to record patterns of nursing and educational behaviour under a 12 hour as compared to an 8 hour shift. Lower levels of ward based education occur under the 12 hour shift. Students pair up with trained staff less. Rather they work alone or with other students more. They also have less contact with patients than under an 8 hour shift.

Attitude of Health Personnel↗
PubMed1991

Identification of a secretory IgA receptor on breast-milk macrophages: evidence for specific activation via these receptors.

Binding of secretory IgA (sIgA) to human milk macrophages was identified by rosette formation with sIgA-sensitized indicator cells and competitive inhibition binding studies with [125I]-sIgA. Macrophages formed rosettes with sIgA-sensitized sheep red blood cells that were inhibited by sIgA (87%) but not IgG. Both IgA1 and IgA2 inhibited sIgA-sensitized sheep red blood cell rosette formation. Rosette formation was completely inhibited by galactose, partially inhibited by asialofetuin, and unaffected by mannose. [125I]-labeled sIgA binding to macrophages reached a plateau after 60 min, was dependent on the number of macrophages in culture, and was specifically inhibited by unlabeled sIgA. Incubation of macrophage monolayers with increasing concentrations of sIgA-anti-IgA immune complexes resulted in a progressive increase in the oxidative burst and increased secretion of prostaglandins. These studies indicate that human milk macrophages have a receptor for sIgA and that activation of these macrophages may occur via these receptors.

Asialoglycoproteins↗
PubMed1991

Oxytocin influences preovulatory follicular development and advances ovulation in rats.

Oxytocin has been shown to advance gonadotropin secretion in pro-estrus rats. The effects that oxytocin-induced changes have on the ovary were investigated in this study. Oxytocin administered to rats at proestrus 09.00 h, 10.00 h and 11.00 h advanced follicular growth, progesterone secretion, and the time of ovulation. However, both treated and control groups of rats ovulated similar numbers of oocytes and the oocytes released were of similar fertility. Because oxytocin has been shown to induce early LH and FSH release the effects of oxytocin administration on the ovary were possibly an indirect action involving the pituitary. The results of this investigation indicate that exogenous oxytocin alters the timing but not the fertility of periovulatory events.

Animals↗
PubMed1991

Human recombinant GM-CSF in allogeneic bone marrow transplantation for leukaemia: double-blind placebo controlled trial.

A double-blind randomised trial compared 20 patients with leukaemia receiving human recombinant granulocyte macrophage colony stimulating factor (GM CSF), with 20 patients receiving placebo for 14 days after allogeneic matched sibling bone marrow transplantation. The median neutrophil count at 14 days was significantly higher in the GM CSF group (1.90 vs. 0.46 x 10(9)/l). The duration of hospital stay, the number of antibiotic days, and the number of fever days was the same for both patient groups. The lymphocyte count was significantly higher in the GM-CSF group than in the placebo group between days 10 and 15 after transplantation. The GM-CSF group had lower haemoglobin concentrations and platelets counts, and higher plasma urea creatinine and bilirubin, than the placebo group. There was no evidence that GM CSF was associated with a greater incidence of leukaemic relapse.

Bone Marrow Transplantation↗
PubMed1990

AST:ALT ratios.

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Alanine Transaminase↗