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P A In't Veld

Publications and source records attributed to P A In't Veld.

15 recordsLinked to original sources
PubMed1997

Determination of the parent of origin in nine cases of prenatally detected chromosome aberrations found after intracytoplasmic sperm injection.

Prenatal cytogenetic analysis of 71 fetuses conceived by intracytoplasmic sperm injection (ICSI) resulted in the detection of nine (12.7%) chromosome aberrations including two cases of 47,XXY, four cases involving a 45,X cell line and three autosomal trisomies. Molecular analysis of the parental origin of the deleted or supernumerary chromosome was performed by using polymorphic microsatellite markers. Six cases involving a sex chromosome abnormality were found to be of paternal origin while the two trisomic cases that could be analysed were of maternal origin. Two cases involved the same infertile couple who had two consecutive ICSI pregnancies terminated because of a chromosome abnormality. The replaced embryos in both cases originated from a single batch of ICSI fertilized oocytes of which part was used to initiate the first pregnancy and part was cryopreserved and used to initiate the second pregnancy.

Chromosome Aberrations↗
PubMed1997

Intracytoplasmic sperm injection (ICSI) and chromosomally abnormal spermatozoa.

An infertile couple was referred for intracytoplasmic sperm injection (ICSI) because of primary infertility and oligoasthenoteratozoospermia (OAT) in the male. It was observed that although the sperm cells presented with an unusual head size and multiple tails they were able to fertilize the oocytes after ICSI. Subsequent molecular cytogenetic analysis demonstrated de-novo chromosome abnormalities in virtually all sperm cells with 40% diploidy and 24% triploidy in addition to aneuploidy for the sex chromosomes.

Adult↗
PubMed1996

Early prenatal diagnosis of Fanconi anaemia in a twin pregnancy, using DNA analysis.

We present a case of prenatal diagnosis of Fanconi anaemia (FA) in a pair of twins at 14 weeks of gestation. The parents had previously had two children: a healthy boy and a boy with FA belonging to complementation group C (FAC). The FA patient is a compound heterozygote, carrying a 322delG and a IVS4+4A-->T mutation in the FAC gene. Prenatal DNA analysis showed that both fetuses were heterozygous for different mutations in the FAC gene. Both fetuses had normal male karyotypes. At 36 weeks the twins were born. They did not show congenital anomalies.

Adult↗
PubMed1995

Increased incidence of cytogenetic abnormalities in chorionic villus samples from pregnancies established by in vitro fertilization and embryo transfer (IVF-ET).

We studied 201 pregnancies that were established by in vitro fertilization and embryo transfer (IVF-ET) and compared the frequency of cytogenetic abnormalities with that found in a large control population matched for indication group (advanced maternal age) and time of sampling. A total of 252 IVF-ET fetuses were cytogenetically analysed by either chorionic villus sampling (CVS; n = 80) or amniocentesis (n = 172). Eleven chromosome abnormalities were found in the CVS group (13.8 per cent); among them, a 45,X/46,X,dic(Y)(q11)/46,X,del(Y)(q11) mosaic that was found in an IVF pregnancy established by intracytoplasmic sperm injection (ICSI), four cases of trisomy 21, and three cases of trisomy 7 confined to the placenta. The results indicate a statistically significant three- to five-fold increase in both confined placental abnormalities (P < 0.008) and true fetal chromosome anomalies (P < 0.04). In the amniocentesis group, identical rates (1.7 per cent) of chromosome abnormalities were found in the IVF-ET and control groups. It is concluded that late first trimester, but not early second trimester, IVF-ET pregnancies are characterized by an increased frequency of cytogenetic abnormalities found at prenatal diagnosis.

Adult↗
PubMed1993

Interaction of interleukin-1 with islet beta-cells. Distinction between indirect, aspecific cytotoxicity and direct, specific functional suppression.

A 5-day culture of adult rat islets with human recombinant IL-1 beta (3 U/ml) resulted in the death of most alpha-cells and 50% of beta-cells. The IL-1--exposed islet tissue contained--in addition to poorly granulated beta-cells--patches of outgrowing monolayers and dispersed activated macrophages. In purified alpha- and beta-cell preparations, no cytodestructive effects of IL-1 (as high as 30 U/ml) were noticed, indicating that the cytokine is in itself not a beta-cell--selective killer. Pure beta-cells were, on the other hand, more sensitive (from 0.3 U/ml on) than intact islets to an IL-1--induced suppression of hormone synthesis. This inhibitory action was reversible and affected predominantly the production of insulin, leading to degranulated cells with modified shape and attachment. Further studies with IL-1 should take into account that isolated islet preparations do not allow distinction between its irreversible, indirect, and aspecific beta-cell toxicity and its reversible, direct, and specific suppression of beta-cell functions. It is not yet known whether IL-1--suppressed beta-cells exhibit an altered sensitivity to beta-cell--toxic conditions.

Animals↗
PubMed1991

Transplantation of purified islet cells in diabetic rats. I. Standardization of islet cell grafts.

A standardized procedure was developed for the preparation of rat islet cell grafts with selected cell number and composition. After collagenase digestion of pancreases and elutriation of tissue fragments, islets were isolated and dissociated, and cells were purified by autofluorescence-activated cell sorting. Approximately 30% of the initial beta-cell mass was lost during digestion and elimination of small mostly exocrine particles. Fifty percent was recovered in isolated islet preparations and 30% in the purified beta-cell suspensions of greater than 95% purity and viability. Sorting according to cellular flavin adenine dinucleotide content discriminated islet beta-cells from islet endocrine non-beta-cells, fibroblasts, leukocytes, and exocrine cells. Purified endocrine islet cell grafts were prepared by aggregating 10(6) pure beta-cells with or without 8 x 10(5) pure endocrine non-beta-cells. In contrast to intact islets, the purified aggregates were devoid of nonendocrine and damaged cells. Intraportal implantation of a pure beta-cell graft rapidly and permanently normalized the diabetic state of streptozocin-administered animals. The standardized preparation of purified beta-cell grafts allows us to address several metabolic and immunological questions concerning islet cell transplantation in diabetes.

Animals↗
PubMed1988

Glucose stimulates proinsulin biosynthesis by a dose-dependent recruitment of pancreatic beta cells.

Glucose is a well-known stimulus of proinsulin biosynthesis. In purified beta cells, the sugar induces a 25-fold increase in the synthesis of insulin immunoreactive material over 60-min incubation. Autoradiographic analysis of the individual cells shows that this effect is achieved via dose-dependent recruitment of pancreatic beta cells to biosynthetic activity. Recruitment of beta cells is also seen in isolated islets exposed to glucose. The sigmoidal dose-response curve for glucose-induced proinsulin biosynthesis thus reflects a heterogeneous responsiveness of pancreatic beta cells rather than a progressively increasing activity of functionally homogeneous cells. Dose-dependent recruitment of functionally diverse cells may be a ubiquitous mechanism in tissue function.

Animals↗
PubMed1988

In situ analysis of pancreatic islets in rats developing diabetes. Appearance of nonendocrine cells with surface MHC class II antigens and cytoplasmic insulin immunoreactivity.

Aberrant expression of MHC class II molecules on endocrine cells has been proposed to induce autoimmune reactions in thyroid and endocrine pancreas. The present study examines whether MHC class II positive insulin-containing islet cells occur at the onset of diabetes in rats, in analogy to the findings in man. At the onset of diabetes, both streptozotocin-treated and diabetes-prone BB rats exhibited numerous class II positive islet cells that presented ultrastructural features of monocytes and were surrounded by class II negative islet B cells. These class II positive cells were characterized by vacuoles that contained insulin immunoreactive granules and disrupted membranes. Similar cells also appeared positive for the monocyte marker OX-42. The presence of class II positive monocytes with insulin-containing vacuoles may indicate a removal of damage B cells by infiltrating leukocytes. A similar electron microscopical study in man will be necessary to distinguish the putative endocrine pancreatic B cells with aberrant class II expression from infiltrating nonendocrine class II positive cells with insulin-containing phagosomes.

Animals↗
PubMed1988

Interaction of sulfonylureas with pancreatic beta-cells. A study with glyburide.

In this study on purified rat pancreatic beta-cells, we show that the second-generation sulfonylurea glyburide stimulates insulin release through a direct interaction with the beta-cells. During static incubations, 2 microM glyburide releases 0.16 pg insulin per beta-cell, which corresponds to a half-maximal glucose stimulation. This effect occurs independently from the glucose-recognition unit, being detectable at both nonstimulatory and stimulatory glucose concentrations and proceeding without alterations in the rate of glucose oxidation. The secretagogue action of glyburide appears not to be mediated through cAMP but is potentiated by cAMP-generating substances such as glucagon (10(-8) M; 0.31 pg insulin released per beta-cell). Its 10-fold higher potency in isolated islets is attributed to the markedly higher cAMP levels that are maintained in islet beta-cells under the influence of locally released glucagon. Perifused pancreatic beta-cells respond to glyburide with a biphasic insulin release. After removal of the drug, the cells continue to secrete insulin at the same rate for greater than or equal to 30 min. This prolonged secretory activity coincides with a cellular accumulation of the drug, primarily in association with membranes of secretory vesicles and mitochondria. Tolbutamide also stimulates insulin release from pure beta-cells, but it is less powerful on a molar basis and does not lead to a sustained hormone release after its removal from the extracellular medium. We conclude that the hypoglycemic action of glyburide is at least partly the result of a direct interaction with pancreatic beta-cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Glucose alters configuration of gap junctions between pancreatic islet cells.

In rat pancreatic islets, gap junctional subunits (GJS) occur under two different configurations, namely in linear single strands and in polygonal particle aggregates. The present freeze-fracture study demonstrates that GJS can rapidly (dis)assemble into one of these membrane specializations without changes in their total number. Isolation of the pancreatic gland and its perfusion at 2.8 mM glucose is accompanied by a decrease in polygonally packed GJS from 46 to 16%. A rise in medium glucose concentration is followed, within 10 min, by a dose-dependent increase in the percent polygonal particles. This glucose effect on gap junction configuration is calcium dependent and reversible upon glucose removal; it is still entirely detectable when protein synthesis is blocked by cycloheximide. These results indicate that islet gap junctions are dynamic structures that rapidly adjust their configuration to extracellular regulators of beta-cell function. In the light of previous observations, it is suggested that this rapid (dis)assembly of gap junctional structures be considered as a component in the ionic and metabolic coupling between insulin-containing beta-cells of the pancreas.

Animals↗
PubMedDate not supplied

Immunogold-silver labeling in histology.

Immunogold-silver staining is a relatively new technique in light-microscopic immunocytochemistry. It is based on silver enhancement of 1 to 10 nm gold probes immunologically bound to antigenic determinants in tissue sections. The detection efficiency of this third-generation detection technique is compared to that of the peroxidase-based ABC technique in routinely processed, paraffin-embedded, human biopsy material.

Gold↗