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Biomedical subjects

M A Masini

Publications and source records attributed to M A Masini.

36 records · Page 2Linked to original sources
PubMed1997

Pro-opiomelanocortin (POMC) expression and immunolocalization of POMC-related peptides in the ovary of Protopterus annectens, an African lungfish.

Antisera against adrenocorticotropic hormone (ACTH), alpha-melanocyte-stimulating hormone (alpha MSH) and beta-endorphin were used to localize pro-opiomelanocortin (POMC)-derived peptides in the ovary of the African lungfish Protopterus annectens by immunohistochemistry. Immunoreactivity was observed in the granulosa and the internal theca of the vitellogenic follicles. No immunoreactivity was observed in immature follicles. Using human POMC cDNA as the hybridization probe POMC-like mRNA was identified in situ in cells of the granulosa and internal theca of the vitellogenic follicles. No labeling was observed in primordial follicles. The demonstration in the same cells of POMC mRNA and POMC-related peptides immunoreactivity indicates a local production of the opiate hormones.

Adrenocorticotropic Hormone↗
PubMed1997

Vasoactive peptides in the heart of Champsocephalus gunnari.

The presence of vasoactive peptides known to control cardiovascular functions in mammals and sub-mammalian vertebrates was investigated in the sub-Antarctic icefish Champsocephalus gunnari. Western immuno blotting was used to demonstrate immunoreactive atrial natriuretic peptide (ANP), angiotensin II (Ang II), bradykinin (BK) and endothelin-1 (ET-1) in heart homogenates. Immunohistochemistry was used to investigate the distribution of ANP, Ang II, BK and ET-1 in the cardiocytes of the three chambers of the heart (atrium, ventricle and the very short conus arteriosus).

Animals↗
PubMed1996

Atrial natriuretic peptide, bradykinin, and angiotensin II-like immunoreactivity in the harderian gland of the terrapin Pseudemys scripta: response to osmotic stress.

The Harderian gland of the terrapin Pseudemys scripta has four types of acinar cells. Type IV cells are very similar to the salt secreting cells of the salt secretory glands of various marine vertebrates. The presence and localization of the Ile5-Angiotensin II, Atrial Natriuretic Peptide, and Bradykinin has been investigated by immunohistochemical methods. Immunoreactivity is confined to the type IV cells. Changes in the environmental salinity resulted in different patterns in the immunoreactivity especially after incubation with Ab-Angiotensin II and Ab-Atrial Natriuretic Peptide. Immunoreactive Angiotensin II cells are more numerous in animals maintained in distilled water, when reabsorption of sodium is needed. In contrast, immunoreactive Angiotensin II cells are very few in animals maintained in seawater. On the contrary, the number of immunoreactive cells for Atrial Natriuretic Peptide is high in seawater maintained animals, and weaker in animals in distilled water. The type IV cell may be considered a candidate for ion regulation in the terrapin Harderian gland.

Acclimatization↗
PubMed1996

Immunocytochemical localization of atrial natriuretic factor and autoradiographic distribution of atrial natriuretic factor binding sites in the brain of the African lungfish, Protopterus annectens.

The localization of atrial natriuretic factor (ANF)-immunoreactive elements was investigated in the brain of the African lungfish, Protopterus annectens, by using antisera raised against rat and human ANF(1-28). Concurrently, the distribution of ANF binding sites was studied by autoradiography using radioiodinated human ANF(1-28) as a tracer. In general, there was a good correlation between the distribution of ANF-immunoreactive structures and the location of ANF binding sites in several areas of the brain, particularly in the ventral part of the medial subpallium, the rostral preoptic region, the preoptic periventricular nucleus, the caudal hypothalamus, the neural lobe of the pituitary, and the mesencephalic tectum. In contrast, mismatching was observed in the pallium (which contained a high density of binding sites and a low concentration of ANF immunoreactive elements) as well as in the lateral subpallium and the medial region of the ventral thalamus, in which a low concentration of binding sites but a high density of ANF-immunoreactive fibers were detected. The present data provide the first localization of ANF-related peptides in the brain of dipnoans and the first anatomical distribution of ANF binding sites in the brain of fish. The results show that the ANF peptidergic systems of P. annectens exhibit similarities with those previously described in the frog Rana ridibunda, supporting the existence of relationships between dipnoans and amphibians. The location of ANF-like immunoreactivity and the distribution of ANF binding sites suggest that ANF-related peptides may act as hypothalamic neurohormones as well as neurotransmitters and/or neuromodulators in the lungfish brain.

Animals↗
PubMed1996

The kallikrein-kinin and renin-angiotensin systems in the kidney of an African lungfish, Protopterus annectens.

Renin-like activity (RLA), angiotensin I converting enzyme-like (ACELA), and kallikrein-like activity (KLA), activities of the key enzymes of renin-angiotensin and kallikrein-kinin systems, were sought in the kidney of the African lungfish Protopterus annectens during the aquatic phase. RLA, examined by RIA (using porcine angiotensinogen as substrate), was 0.38 +/- 0.05 ng angiotensin I/mg protein/hr. ACELA and KLA were investigated in assays spectrophotometrically. ACELA, measured at 37 and at 20 degrees , was, respectively, 1.55 +/- 0.55 and 0.61 +/- 0.23 nmol hippurate/min/mg protein. KLA was 7.34 +/- 0.93 mU/mg protein in the crude kidney extract and 31.05 +/- 7.50 mU/mg protein after electrophoretic purification. Renal kininogenase activity was inhibited by 100% by D-Phe-Phe-Arg-chloromethyl ketone (10 microM), 98% by phenylmethylsulfonyl fluoride (2 nM), and 91% by aprotinin (1000 kIU). The apparent molecular weight of the renal kininogenase on SDS-PAGE was 27,000 Da. Both the renal enzyme and the purified glandular kallikrein, used as a control, have the same mobility on polyacrylamide gel electrophoresis. Immunoreactivities toward angiotensin II and bradykinin were localized by double immunostaining in the same cells of the proximal tubules. Putative angiotensin II receptors were demonstrated immunohistochemically, in the supranuclear region of proximal tubular cells, using an antibody to the sequence between amino acids 225 and 237 of the mammalian AT1 receptor.

Amyloid↗
PubMed1995

Neuropeptide tyrosine in the brain of the African lungfish, Protopterus annectens: immunohistochemical localization and biochemical characterization.

Lungfishes, which share similarities with both fishes and amphibians, represent an interesting group in which to investigate the evolutionary transition from fishes to tetrapods. In the present study, we have investigated the localization and biochemical characteristics of neuropeptide Y (NPY)-immunoreactive material in the central nervous system of the African lungfish, Protopterus annectens. NPY-immunoreactive cell bodies were found in various regions of the brain, most notably in the telencephalon (septal area, ventral striatum, and nucleus accumbens), in the diencephalon (preoptic nucleus, periventricular region of the hypothalamus, and ventral thalamus), and in the tegmentum of the mesencephalon. A strong immunoreaction was also detected in cell bodies of the nervus terminalis. Immunoreactive nerve fibers were particularly abundant in the ventral striatum, the nucleus accumbens, the diagonal band of Broca, the hypothalamus, and the mesencephalic tegmentum. Positive fibers were also seen in the median eminence and in the neural lobe of the pituitary. The NPY-immunoreactive material localized in the brain and pituitary was characterized by combining high-performance liquid chromatography (HPLC) analysis and radioimmunological quantitation. The displacement curves obtained with synthetic porcine and frog NPY and serial dilutions of brain and pituitary extracts were parallel. Reversed-phase HPLC analysis of telencephalon, diencephalon, and pituitary extracts resolved a major NPY-immunoreactive peak that coeluted with frog NPY. The similarity between the distribution of NPY-containing neurons and the biochemical characteristics of the immunoreactive peptide in the brain of lungfish and frog strongly favors a close phylogenetic relationship between dipnoans and amphibians.

Animals↗
PubMed1995

Distribution of FMRFamide-like immunoreactivity in the brain of the lungfish Protopterus annectens.

The distribution of FMRFamide-like immunoreactive peptides was studied in the brain of the African lungfish, Protopterus annectens, using the indirect immunofluorescence technique. The main populations of FMRFamide-positive cell bodies were detected in the forebrain and in the mesencephalic tegmentum. In the telencephalon, only a small number of FMRFamide-immunoreactive neurons was localized at the level of the subpallium, in the nucleus septi medialis. The diencephalon contained two prominent groups of FMRFamide-positive cell bodies located in the preoptic and periventricular preoptic nuclei. The thalamus exhibited only scattered FMRFamide-immunoreactive perikarya in its ventral part. In the mesencephalon, a group of positive cell bodies was identified in the caudal region of the tegmentum. A strong immunoreaction was also detected in the nervus terminalis. In the pituitary, most of the cells of the intermediate lobe were brightly stained. FMRFamide-like immunoreactive fibers and nerve terminals were widely distributed in the brain. In the telecephalon, numerous fibers were observed in several regions of the pallium and subpallium. A dense plexus of fibers was found in the hypothalamus and the thalamus. Immunoreactive fibers were seen coursing along the ventral wall of the infundibular cavity and terminating in the pars nervosa of the pituitary. The tectum and the ventral mesencephalon were also densely innervated. In contrast, the caudal brainstem only showed scarce immunoreactive processes. Coexistence of FMRFamide- and neuropeptide Y-like immunoreactivity was observed in the preoptic nucleus and in the nervus terminalis. The widespread distribution of FMRFamide-immunoreactive neurons in the brain and pituitary of P. annectens suggests that the peptide may exert both neuromodulator and neuroendocrine functions. The similarity between the distribution patterns of FMRFamide and neuropeptide Y in the brain of lungfish and amphibians supports the concept of a close phylogenetic link between these two groups.

Animals↗
PubMed1995

Angiotensin II binding sites in the rat pancreas and their modulation after sodium loading and depletion.

Specific 125I angiotensin II binding sites were identified in the rat pancreas by radioreceptor assay, autoradiography and immunohistochemistry. Scatchard analysis of the binding in normal rats yielded a Kd of 0.51 +/- 0.23 nM with a Bmax of 15 +/- 3.5 fmol/mg protein (means +/- SD, n = 6). Changed plasma sodium concentration resulted in modifications in the binding affinity and capacity. Sodium loading depressed both Kd (0.36 +/- 0.1 nM) and Bmax (6.4 +/- 0.1 fmol/mg protein), while sodium depletion elevated both Kd (2.03 +/- 0.3 nM) and Bmax (45 +/- 3.5 fmol/mg protein) (means +/- SD, n = 6). Autoradiography using 125I Ang II and immunohistochemistry of the binding sites saturated with unlabeled Ang II and incubated with Ab-Ile5 Ang II, revealed localization of the binding sites on the islet cell membranes and in the exocrine pancreas.

Angiotensin II↗
PubMed1994

Renin-like activity, angiotensin I-converting enzyme-like activity, and osmoregulatory peptides in the dogfish rectal gland.

Renin-like activity (RLA) and angiotensin I-converting enzyme-like activity (ACELA), two key enzymes of the renin-angiotensin cascade (RAS), were sought in the dogfish rectal gland. RLA was 1.1 +/- 0.2 ng Ang I/mg protein/hr after incubation with porcine angiotensinogen and 0.8 +/- 0.1 ng Ang I/mg protein/hr after incubation with homologous plasma. ACELA was 7.22 +/- 1.08 and 8.87 +/- 1.9 nmol hippurate generated/min/mg protein respectively, at 0 and 37 degrees. The presence of these enzymes may indicate the presence of an endogenous RAS-like system in the rectal gland. Angiotensin II (Ang II) and atrial natriuretic peptide (ANP) binding sites were demonstrated autoradiographically in the subcapsular region of the gland, suggesting a possible interaction of the two hormones in the blind outer ends of the rectal gland tubules. Immunoreactivities toward Ang II, ANP, bombesin, vasoactive intestinal polypeptide (VIP), glucagon, and somatostatin were differentially localized in the rectal gland within three concentric zones with potentially different functional activities. In the capsule, there was a strong positive ir-glucagon reaction and a slightly weaker reaction for ir-somatostatin and VIP. In the blind outer ends of the tubules (in the subcapsular zone), strong immunoreactivity was present toward all the tested peptides except glucagon and somatostatin. In the inner zone and in the central canal, only a weak immunoreactivity toward Ang II and glucagon was observed.

Angiotensin II↗
PubMed1992

Renin and angiotensin converting enzyme in elasmobranchs.

Renin-like activity (RLA) and angiotensin I converting enzyme-like activity (ACELA), the two key enzymes of the renin-angiotensin system (RAS), were sought in the elasmobranch Scyliorhinus canicula. Renal extracts were desalted in a G-25 and eluted in a G-100 Sephadex column (calibration 15,000-70,000). The fractions were concentrated in a vacuum device. A 48,000-MW fraction incubated with synthetic and porcine angiotensiongen generated angiotensin I estimated by RIA. This same fraction was vasopressor in rats and dogfish. ACELA was sought in gill, heart, liver, spleen, pancreas, intestine, kidney, gonads, brain, skin, and muscle of dogfish using a spectrophotometric assay. The highest level of ACELA was found in the gills followed by spleen, kidney, and brain (33.79 +/- 2.3, 29.56 +/- 1.0, 14.62 +/- 1.0, and 13.80 +/- 2.3 nmol hippurate/min/mg protein, respectively). Intestine, gonads, skin and muscle contained no measurable amounts of ACELA. Captopril inhibited enzymatic activity from all ACELA containing tissues.

Animals↗
PubMed1992

A new surgical technique for tibial tubercle transfer in total knee arthroplasty.

Several methods are described for extensor mechanism realignment in total knee arthroplasty, including lateral release, medial reefing, V-Y quadricepsplasty, and tibial tubercle transfer. Each has its indications, merits, and pitfalls. The advantages of tibial tubercle transfer include precise realignment of the quadriceps mechanism, the ability to properly locate the patella proximally or distally, and maintenance of quadriceps power. The authors present a new technique for tibial tubercle transfer in total knee arthroplasty. Important points include (1) full-thickness medial and lateral soft tissue flaps that are anchored to bone and cover the transferred tubercle at the end of the procedure; (2) osteotomy of a long (10-cm) strip of tubercle and tibial crest; (3) placement of the osteotomized segment in a prepared, inset cancellous bone bed; and (4) fixation of the graft with multiple staples that hold the graft in place without being inserted through the graft. The method described will allow surgeons to perform tibial tubercle transfer reproducibly while avoiding the frequently cited complications of nonunion, loss of fixation, and wound slough.

Aged↗
PubMed1989

Intrarenal localization of angiotensin II specific binding in rat fetuses.

Specific binding sites for angiotensin II were localized in the developing rat kidney (18th day of pregnancy and immediately before birth) by autoradiography using [125I]-ileu-5-angiotensin II either perfused in vivo through the fetal aorta or added in vitro to frozen sections in an incubation mixture. Specific binding was localized in the walls of the afferent and efferent arterioles, in the intraglomerular cells and in the peritubular arterioles of the subcapsular cortical zone. The immunohistochemical analysis, carried out on receptors saturated with unlabelled angiotensin II perfused through the mother's aorta, confirmed the autoradiographical localization. Antisera against ileu-5-angiotensin II were used in the indirect immunofluorescence technique and in the PAP method. Immunolocalization of angiotensin II was also found in the proximal tubule and in the thick ascending limb of Henle's loop.

Animals↗
PubMed1988

Angiotensin II specific receptors in subcommissural organ.

In the subcommissural organ of male rats, a circumventricular organ situated inside the blood-brain barrier, specific receptors for angiotensin II were demonstrated by binding studies on homogenated membranes and by autoradiography carried out on frozen sections using 125I-angiotensin II. The receptor sites were localized in the subnuclear region of cells of the subcommissural organ. A single class of binding sites was found whose capacity was modulated by changes in the sodium plasma concentration which led to variations in plasma volume.

Angiotensin II↗
PubMed1988

Angiotensin II vascular receptors in fetal and neonatal rats.

Specific binding sites for angiotensin II in aorta and renal arteries have been studied in rat fetuses (18th day of pregnancy) and 1-day-old newborn rats by binding studies in arterial membranes using [125I] ileu-5-angiotensin II. One type of angiotensin receptor was found both in fetuses and in the newborns; the capacity of this (RT) decreased immediately after birth (from 0.06 +/- 0.01 nM to 0.02 +/- 0.005 nM; +/- SEM) and the affinity (Kd) increased at birth (from 3.5 +/- 0.6 nM to 19.5 +/- 1.2 nM; +/- SEM). Localization of the specific binding sites was studied by autoradiography on arteries from fetal and newborn rats either perfused with iodinated angiotensin II by cannulation of the aorta or in vitro on cryostat sections incubated with the radioactive angiotensin II. Both in fetuses and in the newborn the binding sites were located in the tunica media of the arteries.

Aging↗
PubMed1988

Immunocytochemical localization of peptides in the endocrine pancreas of the snakes Vipera aspis and Natrix maura.

The endocrine pancreas of Vipera aspis and Natrix maura has been investigated by immunocytochemistry for the presence of six peptides reported to occur in Mammals or in Reptiles. Gastrin/CCK and PP were absent in the endocrine cells, VIP was located within nerve terminals only. Insulin, Glucagon, and Somatostatin were localized both in Vipera and Natrix, generally with a ring of D (Somatostatin) cells surrounding a core of Glucagon (A) and Insulin (B) producing cells; however frequent clusters of D cells are intermingled with the other endocrine cells. Statistical evaluations on the percentages of these 3 cell types showed preponderance of A cells in Natrix whereas in Vipera no significant difference was found between the number of A and B cells. The D cells showed a uniform distribution in the pancreas of the 2 studied species, in any case with a percentage slightly inferior to those of B cells.

Animals↗
PubMed1987

Osmotic stress, plasma renin activity, and spermatogenesis in Vipera aspis.

Circulating electrolytes (Na+, K+), plasma renin-like activity, testosterone, and testis morphology were investigated in early summer during the spermatogenic progressive phase in Vipera aspis subjected to sodium loading and sodium depletion. After sodium loading, plasma sodium and plasma testosterone levels were significantly elevated compared with those of controls, while plasma renin-like activity was depressed, spermiogenesis was increased, the epithelium lining the epididymis was very thick, and the Leydig cells were hypertrophied. After sodium depletion, plasma sodium and plasma testosterone levels were significantly depressed and plasma renin-like activity was significantly elevated. Spermiogenesis seemed to be slightly regressed: the epithelium lining the epididymis was very thin, and the lumen was devoid of spermatozoa. The Leydig cells were hardly visible. All the data strongly suggest that osmotic stress affects gonadal activity in the snake. V. aspis.

Animals↗
PubMed1986

Immunohistochemical localization of gut peptides in the small intestine of snakes.

The small intestine of Vipera aspis, Natrix natrix and Natrix maura has been investigated for the presence of six gastrointestinal peptides reported to occur in Mammals. Gastrin/CCK and somatostatin were present in endocrine cells of the gut of all the species investigated. The neuropeptide vasoactive intestinal polypeptide was located within nerve terminals and in body cells only in the small intestine of Vipers and was absent in the Natricinae investigated. No immunoreactivity was found with the antisera to glucagon, secretin and motilin.

Animals↗