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M A Kessler

Publications and source records attributed to M A Kessler.

31 records · Page 2Linked to original sources
PubMed1991

Expression of prolactin-related hormones in the early bovine conceptus, and potential for paracrine effect on the endometrium.

Hormones related to the pituitary hormones PRL and GH are produced by the utero-placental unit of many species. In the cow, these include bovine placental lactogen (bPL) and a distantly related subfamily including the protein encoded by bovine PRL-related complementary DNA I (bPRCI). In the present studies, we defined the onset of expression of these genes in order to begin to study the regulation of their expression and function before implantation. Messenger RNA levels of both bPL and bPRCI were assessed by dot blot analysis of total RNAs prepared from conceptuses on days 15-25. Specific transcripts were not detectable at day 15 but were readily apparent beginning at day 17. To define the portions of the placenta responsible for expressing these genes, RNA was prepared from chorion (separated into cotyledons and intercotyledonary membrane), allantois, and amnion from day 58 gestation and analyzed by Northern hybridization. Transcripts for both these hormones were confined to the chorion, with intercotyledonary RNA containing at least as much as that prepared from cotyledons. To localize the product of these genes, extraembryonic membranes were immunostained with bPL and bPRCI antisera. Mononucleated trophoblastic cells stained for bPL and bPRCI at day 18; similar staining was apparent at days 23 and 24, as well as in some but not all binucleated cells. Microsomes prepared from endometrium exhibited specific binding of bPL throughout pregnancy as well as during the luteal phase of the cycle. At midgestation, these high affinity, low capacity receptors (dissociation constant of 1.27 x 10(-10) M, maximum binding capacity of 44.2 fmol/mg protein) demonstrated a selective affinity for bPL in preference to bGH and bPRL. Using this radioreceptor assay, we demonstrated the presence of bPL at nanomolar concentrations in washings from the uterine lumen, suggesting that bPL may exert paracrine effects on the endometrium.

Animals↗
PubMed1990

Characterization of a novel prolactin-related protein from bovine fetal placenta.

The bovine fetal placenta transcribes a family of PRL-related genes that are distinct from the bovine placental lactogen gene. To demonstrate that one of these cDNAs, bovine PRL-related cDNA-I (bPRCI), is expressed at the protein level, a recombinant form of the bPRCI product was overexpressed in Escherichia coli. An antiserum raised against this recombinant product did not cross-react with the pituitary members of the PRL-GH family or with bovine placental lactogen, although cross-reactivity within the bPRC subfamily cannot be ruled out. The antiserum detected a doublet with apparent mol wt of 34,000 and 35,000 in bovine fetal placenta, but not in other fetal tissues. Treatment with several glycosidases revealed a glycoprotein with asparagine-linked carbohydrates of the biantennary complex or hybrid type. We conclude that the bovine fetal placenta expresses at least one of the novel members of this gene family at the protein level.

Amidohydrolases↗
PubMed1989

A subfamily of bovine prolactin-related transcripts distinct from placental lactogen in the fetal placenta.

The placentae of many species express genes homologous to the pituitary hormones. In the bovine, two transcripts distinct from the pituitary hormones have been previously described: bovine placental lactogen (bPL) and bovine prolactin-related cDNA I (bPRCI). Here we provide evidence for a subfamily of prolactin-related transcripts quite different from bPL and the rodent placental homologues, which include proliferin and rat prolactin-related proteins. Bovine prolactin-related cDNAs II and III (bPRCII and bPRCIII) are about 75% similar in nucleotide sequence to one another and bPRCI, but only 56% similar to bPL, and about 45% to the rodent placental transcripts. The deduced amino acid sequences follow a similar pattern: they are about 60% similar to one another, but only about 35% similar to bPL as well as the predicted rodent placental proteins. mRNA levels corresponding to bPL, bPRCI, and bPRCIII in the fetal placenta show distinct patterns. The role of these predicted hormones during pregnancy remains to be determined.

Amino Acid Sequence↗
PubMed1989

Characterization of the gene corresponding to bovine placental prolactin-related cDNA I: evolutionary implications.

We have previously characterized a family of transcripts, isolated from bovine placental tissue, that are related to prolactin (PRL) and are distinct from placental lactogen (PL). Here we describe a PRL-related gene that corresponds to one of these placental transcripts, bPRC-I. Restriction endonuclease mapping and sequence analysis of this gene reveal that it is distributed among five exons spanning approximately 9.2 kb. The site of transcription initiation was determined and repetitive sequences were localized in the first two introns. The nucleotide sequence of the coding region is 64% homologous to the bPRL gene and 44% homologous to the bovine growth hormone (bGH) gene. The 5'-flanking region shows no detectable homology to that of bPRL or bGH. Genomic Southern blot analysis indicates that this gene is a member of a family of PRL-related genes.

Amino Acid Sequence↗
PubMed1988

Bovine placental lactogen: molecular cloning and protein structure.

The bovine placenta secretes at least one hormone with prolactin-like and placental growth-hormone-like activity. The cDNA for bovine placental lactogen was isolated from a bovine fetal cDNA library by virtue of its nucleotide sequence homology to bovine prolactin (70%) and identified as such from amino acid sequence obtained from the amino terminus and internal tryptic fragments from the isolated hormone. The cDNA predicts a preprohormone of 236 amino acids, with a signal peptide of 36 amino acids. A single consensus site for N-glycosylation marks a probable site of carbohydrate addition. The encoded hormone is quite distinct from the pituitary hormones, as well as the primate and rodent placental lactogens and other predicted bovine placental hormones. It is 51% similar to bovine prolactin in amino acid sequence, 30% similar to the protein predicted by bovine prolactin-related cDNA I, about 30% similar to the rodent predicted placental hormones, and only about 20% similar to human placental lactogen and bovine growth hormone. Despite its greater similarity to bovine prolactin, sequence homology in the region of 5' flanking sequences and first exon to bovine prolactin-related cDNA I suggests that bovine placental lactogen may share a common evolutionary origin with this other placentally expressed member of the prolactin gene family.

Amino Acid Sequence↗
PubMed1986

1,25-Dihydroxyvitamin D3-stimulated mRNAs in rat small intestine.

The technique of differential hybridization has been employed to study gene expression associated with vitamin D action on the mammalian intestine. A cDNA library consisting of 10(6) independent recombinants was constructed from poly(A)+ RNA extracted from vitamin D-deficient rats given 1,25-dihydroxyvitamin D3. A survey of 20,000 clones resulted in identification of four distinct cDNAs whose corresponding mRNAs are significantly increased 12 h after an intrajugular dose of 1,25-dihydroxyvitamin D3 given to vitamin D-deficient rats. DNA sequence analysis identified these mRNAs as mitochondrial ATP synthetase, vitamin D-dependent calcium binding protein, cytochrome oxidase subunit I, and cytochrome oxidase subunit III. The time course of response of three of these mRNAs was similar, with maximum values at 12 h after dosing, while that of cytochrome oxidase subunit I showed two peaks at 6 and 18 h following a single dose of 1,25-dihydroxyvitamin D3. The levels of all four mRNAs were elevated in rats supplied with vitamin D when hypocalcemia was produced by dietary calcium restriction.

Animals↗
PubMed1985

The action of 1 alpha,25-dihydroxyvitamin D3 on rat small intestine: changes in translatable mRNA species.

The time course of changes in translatable mRNA from small intestinal mucosa was studied in vitamin D-deficient rats following an intrajugular dose of 1,25-dihydroxyvitamin D3. L-[35S]Methionine-labeled translation products were analyzed by high-resolution one- and two-dimensional electrophoresis. Changes were detected in two distinct proteins, Mr 14,000/pI 6.24 (Band I), and Mr 5,200/pI 4.86 (Band II). These increased to maxima of 1-2% each of the total in vitro-synthesized protein at 12 h after dosing. This represented a 3- and 10-fold increase, respectively, over control values. The time course of these changes suggests that regulation of the levels of the mRNAs coding for these proteins is not involved in the initial (6 h) peak of 1,25-dihydroxyvitamin D3-stimulated intestinal calcium transport in the rat.

Animals↗
PubMedDate not supplied

[Development of a 3-dimensional method to determine the tibial slope with multislice-CT].

AIM: The measurement or, respectively, the correction of the tibial slope is an important subject in the field of knee arthroplasty and in the procedure of cruciate ligament reconstruction. However, a valid value of the tibial slope cannot be obtained from the conventional plain X-rays in a reproducible way. The aim of this study was to evaluate the proximal tibial slope with a new CT measurement system and to compare the values with the X-ray method. METHOD: Using 6 cadaver tibiae, the antero-posterior slope of the proximal tibia was measured at 0 degrees, 2.5 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees, 30 degrees internal rotation using the plain X-ray and spiral CT (3D-MPR reconstruction). Both methods were compared. RESULTS: The variation of the measurement of the tibial slope with the X-ray method was > 5 degrees even if the optimal 0 degrees rotation in the lateral view was applied. Moreover, the measurement error increased to 14 degrees while increasing the rotation of the tibia. Using the new CT system, the error was less than 3 degrees in all measurements. CONCLUSION: The measurement of the tibial slope in the conventional X-ray technique showed a high variation of the values depending on the rotation of the tibia in the lateral view. In contrast, the measurements with the new CT system represented a precise method with a small variation of the tibial slope values. For this reason detailed questions regarding the precise anatomy of the proximal tibia cannot be answered precisely with plain X-rays.

Anterior Cruciate Ligament↗
PubMedDate not supplied

[Postoperatively recurring instability of the shoulder--a fault analysis in 46 cases].

AIM: The successful operative stabilization of the shoulder joint is a demanding surgical procedure. The causality of shoulder instability is complex with in some cases multiple lesions in different anatomical structures. The surgeon has to understand the complexity of factors causing instability in order to be therapeutically successful. The aim of the study was to document the intraoperative pathology in revision instability surgery. METHOD: 46 patients with recurrent postoperative instability were included (8 female, 38 male, follow-up > 12 months). After diagnostic arthroscopy an open revision surgery was performed in all cases. RESULTS: In 19 cases (40%) an insufficient surgical procedure was performed (inadequate capsular shift with worn out labral tissue). Selection of an incorrect surgical technique was the reason for revision in 12 patients (25%). Anamnestically 5 patients reported a re-injury, whereas objectively only one patient described an adequate trauma. The most frequent finding was an open rotator interval (persisting Foramen Weitbrecht), which was seen in 22 cases (46%). CONCLUSION: A stable range of motion of the shoulder is achieved by a variety of different factors, which leads in most instances to a combination of pathological changes in case of a dislocated shoulder. To understand the contributing factors of an instable shoulder joint is a necessity to carry out a successful surgical procedure.

Adult↗