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Biomedical subjects

G Robinson

Publications and source records attributed to G Robinson.

16 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↗
PubMed1979

A formalin fixative for immunochemical and ultrastructural studies on gastrointestinal endocrine cells.

Using indirect immunofluorescence, indirect immunoperoxidase, and unlabelled antibody enzyme techniques, gastrin, pancreatic glucagon, insulin, and somatostatin were localised in sections of both wax- and resin-embedded tissues that had been fixed in a buffered formalin solution. Ultrastructural preservation of the resin-embedded samples was also adequate for combined electron microscopy and light microscope immunochemistry. As the fixative concerned is stable it can be permanently available in surgical units. It is suggested, therefore, that this fixative should prove useful as an alternative to buffered formaldehyde, which must be freshly prepared from paraformaldehyde powder, in institutions where specimen collection is difficult or which have to refer cases with an endocrine involvement to other laboratories for immunochemical and fine structural examination.

Digestive System↗
PubMed1979

Olfactory mucosa in herpes simplex encephalitis.

The olfactory mucosa was examined in three patients dying from herpes simplex encephalitis. It showed changes attributed to infection by the herpes simplex virus. It is suggested that in some patients encephalitis may be a complication of infection of the olfactory mucosa.

Adult↗
PubMed1978

Immune response of the draining and distal lymph nodes during the progressive grwoth of a chemically-induced transplantable rat hepatoma.

The immunological and histological changes occurring in the lymph node draining the site of a progressively growing intramuscular tumour (D192A) implant were monitored during a 4-week time course. Cell-mediated cytotoxicity against hepatoma-D192A and 15-day rat embryo cell targets, was detected with cells derived from the draining "lumbar" lymph node 4 days after tumour implantation and persisted up to the 2nd week of tumour growth, decreasing rapidly during the 3rd week. The observed lymph-node anergy demonstrated in cytotoxicity tests correlated with the histological findings, in that an initial marked paracortical (T-dependent) response also declined towards the end of the 3rd week of tumour growth. The B-dependent cortex showed active lymphocyte follicles in the 2nd week of the time course, and plasma-cell production continued until the experiment was terminated. These changes were shown to occur with the progressive increase in lymph-node mass. Serum antibody specific for the developing tumour was detected during the latter stages of tumour growth. The immunological and histological changes displayed were out of phase with those shown by the draining lymph node.

Animals↗
PubMed1978

Compliance as a factor effecting the patency of a copolyurethane vascular graft.

A new solid-wall vascular graft which has a compliance approximating that of the natural artery has been prepared from a copolyether-urethane material. Six of nine of these compliant grafts implanted in dogs were patent on removal, the longest implant time being 77 days for a 4-mm I.D. femoral artery graft. This is in contrast to noncompliant grafts of the same copolyurethane in which failure usually occurred within 48 hr.

Animals↗
PubMed1975

Immunochemical studies of the endocrine cells of the gastrointestinal tract. I. The use and value of peroxidase-conjugated antibody techniques for the localization of gastrin-containing cells in the human pyloric antrum.

This paper describes and immunochemical localization of gastrin-containing endocrine cells in the human pyloric antrum using antibodies conjugated to horseradish peroxidase. With pre-fixed cryostat sections, a distinct clear-cut staining of gastrin-containing cells can be obtained either by direct or indirect single stain procedures, but may cells containing endogenous peroxidase activity also stain. In order to abolish staining due to endogenous peroxidase, sections were pretreated with a number of inhibitors prior to incubation in immune sera, but the inhibitors used appeared to interfere with the antigenicity of the gastrin molecule since subsequent immunochemical localization was impossible. The application of a double-staining technique, however, allowed us to distinguish easily between those cells which contained endogenous peroxidase and those on to which labelled antibody had been adsorbed. No labelled cells were found in post-fixed cryostat sections of fresh-frozen tissue. The technique is of value because preparations are permanent, a fluorescence microscope is not required, and the same technique can be adapted for use with the electron microscope.

Animals↗
PubMed1975

Bypass grafts for recurrent or complex coarctations of the aorta.

Twenty-three patients aged 5 to 53 years with recurrent or complex coarctations of the aorta were successfully operated upon using bypass grafts. This technique of repair was selected for 5 patients with recurrent coarctation, 11 with long-segment coarctation with or without hypoplasia of the transverse aortic arch, and 7 with inadequate collateral circulation. Nineteen patients had bypass grafts from the left subclavian artery to the distal descending thoracic aorta. The other 4 had a combined approach through a left thoractomy and median sternotomy with grafts between the ascending and descending thoracic aorta. All patients survived the operative procedure. One patient were reexplored for a hemothorax and 5 developed transient postoperative hypertension. There were no instances of abdominal vasculitis or lower extremity paralysis. These patients have been followed from 3 months to 11 years postoperatively, and all but 1 are alive and well. Twenty-two are normotensive, and none have the sequelae of hypertensive disease. Gradients up to only 15 mm Hg exist between upper and lower extremity blood pressures. Five patients have undergone postoperative catheterization and aortography, and all have patent grafts. This procedure is a useful and adjunct in difficult coarctations of the aorta and can be safely performed with excellent reproducible long-term results.

Adolescent↗