PubMed Health⌕ Search

Biomedical subjects

A Verhofstad

Publications and source records attributed to A Verhofstad.

At least 19 recordsLinked to original sources
PubMed2001

Proliferative activity and branching morphogenesis in the human prostate: a closer look at pre- and postnatal prostate growth.

BACKGROUND: To gain further insight into the molecular cell biologic features of prostate development, we investigated the proliferative activity of prostate epithelial and stromal cells and their topographic relationship with neuroendocrine (NE) cell distribution and regional heterogeneity. METHODS: Consecutive sections from 43 prostates taken during autopsy representing fetuses (12-38 weeks of gestation), infants, prepubertal males and adults were double stained for chromogranin A and MIB-1. MIB-1 labeling index (LI) was calculated in the budding tips, forming acini, major collecting ducts, adjacent and non-adjacent stromal compartments. Furthermore, the topographic relationship between proliferating cells and NE cells was evaluated. RESULTS: In the first half of gestation, cell proliferation as revealed by MIB-1 LI was significantly higher in epithelial structures and stroma than in older fetuses and other age groups. MIB-1 LI was higher in budding tips than in other epithelial regions. MIB-1 LI in stroma adjacent to budding tips was not higher than that adjacent to other epithelial branching segments. Co-expression of chromogranin A and MIB-1 staining was not observed. MIB-1 LI was lower in cells in the direct vicinity of chromogranin A positive NE cells than at a distance from NE cells. CONCLUSIONS: Prostate development in the first half of gestation is explosive. Thereafter, the prostate basically is a slow-growing organ. Budding tips are the major growth foci during early prostate development, while stromal growth is evenly distributed throughout the prostate, probably indicating that stromal-epithelial interactions do not manifest in enhanced proliferation at their interface. NE cells may have an inhibitory effect on proliferation of exocrine epithelial cells and are probably only associated with differentiation of prostate exocrine cells in the prostate.

Adult↗
PubMed2001

Heme is a potent inducer of inflammation in mice and is counteracted by heme oxygenase.

Various pathologic conditions, such as hemorrhage, hemolysis and cell injury, are characterized by the release of large amounts of heme. Recently, it was demonstrated that heme oxygenase (HO), the heme-degrading enzyme, and heme are able to modulate adhesion molecule expression in vitro. In the present study, the effects of heme and HO on inflammation in mice were analyzed by monitoring the biodistribution of radiolabeled liposomes and leukocytes in conjunction with immunohistochemistry. Small liposomes accumulate in inflamed tissues by diffusion because of locally enhanced vascular permeability, whereas leukocytes actively migrate into inflammatory areas through specific adhesive interactions with the endothelium and chemotaxis. Exposure to heme resulted in a dramatic increase in liposome accumulation in the pancreas, but also intestines, liver, and spleen exhibited significantly increased vascular permeability. Similarly, intravenously administered heme caused an enhanced influx of radiolabeled leukocytes into these organs. Immunohistochemical analysis showed differential up-regulation of the adhesion molecules ICAM-1, P-selectin, and fibronectin in liver and pancreas in heme-treated animals. Heme-induced adhesive properties were accompanied by a massive influx of granulocytes into these inflamed tissues, suggesting an important contribution to the pathogenesis of inflammatory processes. Moreover, inhibition of HO activity exacerbated heme-induced granulocyte infiltration. Here it is demonstrated for the first time that heme induces increased vascular permeability, adhesion molecule expression, and leukocyte recruitment in vivo, whereas HO antagonizes heme-induced inflammation possibly through the down-modulation of adhesion molecules.

Animals↗
PubMed2001

Development of quality control preparations for immunocytochemical assessment of urokinase-type plasminogen activator.

Quality control of immunochemical and/or immunocytochemical analyses warrants constant reproducibility and reliability of assay performance. In this respect, stable reference preparations containing known quantities of the components to be assessed may serve purposes in the quality assessment of antigen expression levels, including those of the plasminogen activation system. Quality control preparations for the immunocytochemical assessment of urokinase-type plasminogen activator (uPA) were developed using different combinations of cultured cell lines (BLM and IF6), each expressing immunochemically well-defined (by enzyme-linked immunosorbent assay[ELISA]) amounts of the respective component. Cytospins and frozen sections cut from sucrose/Tissue-Tek blocks containing these cell lines demonstrated stable and homogeneous expression of uPA. An excellent correlation was found between the immunocytochemical staining results and the data obtained by ELISA. Because these cell lines are available in practically unlimited quantities, large numbers of nearly identical quality control preparations can be made over a long period of time. Therefore, the incorporation of (combinations of) cell lines in cytospins or sucrose/Tissue-Tek blocks represents a simple model system in establishing quality control preparations for immunocytochemical assessment of components of the plasminogen activator system.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

Neuroendocrine cells during human prostate development: does neuroendocrine cell density remain constant during fetal as well as postnatal life?

BACKGROUND: Knowledge concerning differentiation of neuroendocrine (NE) cells during development of the human prostate is rather fragmentary. Using immunohistochemistry combined with a morphometric method, we investigated the distribution and density of NE cells in the developing human prostate, with special emphasis on the topographical relationship of NE cells with the developing gland. METHODS: Consecutive sections from a total of 42 human prostates taken during autopsy of fetuses (12-38 weeks of gestation), prepubertal males, and young adults were immunostained for chromogranin A and serotonin. Computer-assisted image analysis was used to assess the total number of cells in the different parts of the branching glandular anlage, i.e., budding tips and acini/ducts. Next, the number of NE cells was counted manually. The NE cell density (NE cell index) was then determined. RESULTS: NE cells could first be detected in the prostate from 13 weeks of gestation. By 21 weeks of gestation, all prostates contained NE cells. NE cells were mainly confined to the acinous/ductal regions, while most of the budding tips lacked NE staining. NE cell indexes of individuals were highly variable, mostly in the youngest age group. CONCLUSIONS: In the normal prostate, NE cell density probably remains constant in acini/ducts from fetuses to young adulthood. The presence of neuroendocrine cells in well-developed glandular structures at such an early fetal age and their absence in the less differentiated budding tips possibly indicates that differentiation of NE cells is associated with glandular maturation. NE cells occur preferentially in the acinous/ductal region, implying a paracrine function during secretory differentiation of exocrine epithelial cells.

Adolescent↗
PubMed1999

Serotonin in human allergic contact dermatitis. An immunohistochemical and high-performance liquid chromatographic study.

Allergic contact dermatitis (ACD) is a common clinical condition leading to considerable morbidity. We have recently demonstrated that ketanserin, a serotonin antagonist, significantly inhibits nickel sulphate-induced ACD. Furthermore, serotonin-immunoreactive (IR) cells have previously been demonstrated in normal human cutaneous melanocytes. To further elucidate the role of serotonin in cutaneous contact hypersensitivity, we compared ACD involved skin and uninvolved skin from nickel-allergic patients, and normal skin from healthy volunteers, for the presence of serotonin-like immunoreactive cells using immunohistochemistry. In addition, serotonin concentrations in ACD involved and uninvolved skin were compared by high-performance liquid chromatography (HPLC). In the skin of normal healthy volunteers, the serotonin-IR cells were situated in the basal layer of the epidermis. In uninvolved skin the cells were also situated in the basal layer, but they were more numerous and the immunofluorescence intensity was greater. In involved skin, the IR cells were fewer and they were found higher up in the epidermis. Also, the configuration of these cells was different: they showed enlarged and elongated dendrites as well as dendritic spines. The serotonin antiserum-labelled cells in ACD involved skin were also NKI-beteb positive (the latter is known as a reliable marker of melanocytes). The concentration of serotonin in involved skin was significantly higher than that in uninvolved skin in ACD patients (P < 0.05). Taken together, our previous and present results indicate that serotonin plays an important role in ACD. The basal epidermal serotonin-IR cells are more dendritic in ACD, and are found more superficial in the epidermis, where they might release their content of serotonin, thereby influencing the inflammatory process.

Adult↗
PubMed1998

[Kimura's disease].

An Asian man aged 42 had a pre-auricular swelling on the left with local skin itching. Owing to the highly probably benign nature at examination, surgical treatment was refrained from. One year later, the swelling had increased while the itching was unchanged, so that surgical excision was performed. Morbid-anatomical examination revealed angiolymphoid hyperplasia with eosinophilia, compatible with Kimura's disease. Kimura's disease is a chronic inflammatory disorder which is very rare in Europe, but which is frequently diagnosed in Asian countries and in immigrants from these countries. Tumours in the head and neck region, enlarged lymph nodes and increased eosinophil counts are typical signs. The IgE level is increased. The cause of this disease is so far not clear, although there are indications that an inflammatory reaction to an unknown allergen plays a part. It is essential that this disease should be distinguished in the diagnostic work-up from presence of a malignancy. Fine-needle aspiration cytology is often inconclusive; as a rule the diagnosis can only be made after surgical excision of the tumour. There is no consensus on the treatment of this disease, but symptomatic therapy usually suffices.

Adult↗
PubMed1998

A serotonin-like immunoreactivity is present in human cutaneous melanocytes.

Immunohistochemistry was applied in the investigation of the possible existence of serotonin in human skin. It was found that epidermal melanocytes express a serotonin-like immunoreactivity. The immunoreactivity was associated with both the cytoplasm and the cellular membrane, though the latter was only found in certain cells. The serotonin anti-serum labeled the same cells as NKI-beteb, which is known as a reliable marker of melanocytes. Blocking experiments showed that both serotonin and NKI-beteb have different epitopes in the melanocytes. In in vitro studies, serotonin-like immunoreactivity appeared in approximately 90% of cultured human melanocytes, and was found both in the cytoplasm and also in the nuclei. Thus, we believe the melanocytes to be the origin of serotonin (or a serotonin-like molecule) in the skin.

Antibodies, Monoclonal↗
PubMed1998

Clinical signs and symptoms of acute reflex sympathetic dystrophy in one hindlimb of the rat, induced by infusion of a free-radical donor.

The acute phase of reflex sympathetic dystrophy (RSD) is characterized by the classical signs and symptoms of inflammation (rubor, calor, dolor, tumor and impaired function). As free radicals are involved in acute inflammation, we studied the effects of free radicals in an animal model, especially as to signs and symptoms found in acute RSD. Awake rats were given continuous intra-arterial infusion (1 ml/h) in the left hindlimb, with saline (n = 6) or the free-radical donor tert-butylhydroperoxide (tert-BuOOH, 25 mM, n = 6). During a 24-h infusion period the skin temperature, volume, skin color, function and pain reactions of the paws were observed. After 24 h the rats were killed and both gastrocnemius muscles were histologically analyzed. Infusion with tert-BuOOH induced in the left paw an increased skin temperature, increased volume, redness of the plantar skin, impaired function and increased pain sensation, while these acute RSD signs and symptoms were absent in the saline infused animals. The alterations in pain sensation (spontaneous, mechanical and thermal pain) were similar to findings in the neuropathic animal model. The gastrocnemius muscles of the saline infused rats and the contralateral gastrocnemius muscle of the tert-BuOOH infused rats showed no histological tissue damage. In the left gastrocnemius muscle free-radical-related damage was visible. Induction of free-radical formation in one hindlimb of awake rats mimics the acute signs and symptoms of acute RSD, with alterations in pain sensation as found in the classical neuropathic animal model of RSD, as well as in acute RSD patients.

Acute Disease↗
PubMed1998

Cell kinetics of prostate exocrine and neuroendocrine epithelium and their differential interrelationship: new perspectives.

The prostate gland consists of a complex ductal system lined with exocrine basal and luminal cells, and neuroendocrine epithelial cells. This paper reviews the histologic and molecular cell biologic characteristics of these cells, in normal adult tissue, during prostate morphogenesis, and in the development of benign and malignant neoplastic conditions. Expression of differentiation markers, as well as proliferation and apoptosis markers, growth factors and associated receptors, and abnormalities in genes and chromosomes are reviewed. Accumulating data indicate that (1) pluripotent immortal stem cells are located in the basal cell compartment of the prostate; (2) there is a subpopulation of epithelial cells in the prostate gland (intermediate cells) that have both structural and functional characteristics common to basal and luminal cells, which may be identified in various conditions; and prostate NE cells may have the same common origin as other exocrine cells, and share the same differentiation pathway. A stem cell model is proposed in which both exocrine and endocrine cells are derived from a subpopulation of basal cells (stem cell) that give rise to luminal cells through intermediate cells (pluripotent amplifying cells). These cells are also probably highly implicated in the early development of prostate benign and malignant neoplasia.

Adult↗
PubMed1997

Prostatic neuroendocrine cells have a unique keratin expression pattern and do not express Bcl-2: cell kinetic features of neuroendocrine cells in the human prostate.

We investigated the keratin phenotype and bcl-2 immunoreactivity of neuroendocrine cells in the human prostate to determine whether the postmitotic status of these cells is associated with protection from apoptosis by bcl-2 protein expression and to elucidate the possible cell kinetic relationship between neuroendocrine cells and the other epithelial components of the prostate. Tissue specimens were selected from prostates of 19 patients harboring normal secretory glands (n = 15) and glandular benign prostatic hyperplasia (n = 10). Using a novel sequentially selective destaining immunoenzymatic cytochemical technique we were able to demonstrate the distribution of neuroendocrine cells, keratin markers identifying either basal, luminal, or intermediate cells, and the bcl-2 protein in single sections. Basal cell keratins were expressed in the minority of the neuroendocrine cells. In most of the cells, intermediate and luminal cell keratins were found and bcl-2 was constantly negative. Our findings indicate that neuroendocrine cells and other epithelial cells in the human prostate share a common keratin phenotype and probably originate from a common epithelial precursor. From the absence of bcl-2 we infer that the neuroendocrine cells have no progenitor cell characteristics.

Aged↗
PubMed1996

Intrinsic innervation of the stomach of the fetal pig: an immunohistochemical study of VIP-immunoreactive nerve fibres and cell bodies.

Using an immunohistochemical technique, the presence and distribution of vasoactive intestinal polypeptide (VIP) was investigated in cryostat sections, both tangential and transverse, of the fetal pig's stomach. In all fetuses and in all gastric segments investigated, VIP-like immunoreactive (IR) nerve-cell bodies were seen in all intramural ganglia, and VIP-IR nerve fibres were found in all layers of the gastric wall except the tunica serosa. Consequently, VIP-IR nerve fibres were found to form a periglandular network, to accompany arterioles, to interconnect the intramural ganglia, to encircle both VIP-IR-negative and -positive neurons, and were found in all muscle layers. Despite the fact that VIP-IR seems to be restricted to the intramural nervous elements, some non-specific-reacting VIP-IR glandular cells were noticed in the basal parts of the fundic, antral and pyloric gastric glands. The distribution pattern of VIP in the fetal pig resembles that of the adult pig. This suggests a possible functional role for VIP during fetal life and/or puts forward the suggestion that the stomach of a fetal pig from the second half of the gestation period is prepared, from then on, for postnatal function. High similarities with regard to the general distribution pattern of VIP in the stomach have also been noted between the fetal pig and humans, proving once more that the fetal pig can serve as a good animal model in several research areas. Finally, the morphological data provided here may, combined with the physiological significance of VIP, contribute to a better insight into the physiopathology of economically important gastro-intestinal disorders in the pig, such as gastric ulceration.

Animals↗
PubMed1995

Simultaneous immunoenzymatic staining of catecholamines, catecholamine-biosynthesizing enzymes, and bromodeoxyuridine in adrenal medullary cells of the rat.

The rat adrenal medulla consists mainly of low proliferating, highly differentiated parenchymal cells. By immunocytochemical techniques, two types of parenchymal cells can be identified, norepinephrine (NE)- and epinephrine (E)-storing cells. Bromodeoxyuridine (BrdU), a thymidine analogue often used to identify proliferating cells, can also be detected by immunocytochemical techniques. We developed double- and triple-labeling procedure(s) for simultaneous visualization of NE, E, dopamine beta-hydroxylase (DBH), phenylethanolamine-N methyltransferase (PNMT), and BrdU in rat adrenal medulla. BrdU was administered to 7-week-old Wistar rats by mini-osmotic pumps. Tissues were fixed by perfusion with 4% paraformaldehyde and embedded in paraffin. By immunocytochemistry, first NE, E, DBH, and/or PNMT was detected by an indirect immunoalkaline phosphatase technique with Fast Red or Fast Blue as substrate. Next, incorporation of BrdU was detected with an indirect immunoperoxidase procedure using diaminobenzidine (DAB). Both NE- and E-storing cells, as well as endothelial cells, can incorporate BrdU, i.e., are able to divide. Occasionally, we also found BrdU-stained mitotic figures in E, PNMT and DBH immunoreactive cells. No BrdU incorporation was found in the post-ganglionic neurons of the adrenal medulla. The procedures described enable a detailed cell kinetic study of the NE- and E-storing cells in the adrenal medulla, particularly in the rat, which can lead to a better understanding of cell renewal in the adrenal medullary tissue under normal and pathological conditions.

Adrenal Medulla↗
PubMed1994

Immunologically induced sympathectomy of preganglionic nerves by antibodies against acetylcholinesterase: increased levels of peptides and their messenger RNAs in rat adrenal chromaffin cells.

Systemic administration of murine monoclonal acetylcholinesterase antibodies to rats has been shown to cause selective degeneration of sympathetic preganglionic neurons. In the present study rats were subjected to a single i.v. injection of these acetylcholinesterase antibodies, or to normal IgG or saline for control. Exophthalmos, piloerection and eyelid-drooping (ptosis) were observed within 1 h after administration of the antibodies. Rats were killed at different time-points after antibody administration, and the adrenal glands were analysed by means of indirect immunohistochemistry and in situ hybridization histochemistry. As soon as 3 h after the antibody treatment, a marked increase in the number of chromaffin cells expressing mRNA encoding, respectively, enkephalin, calcitonin gene-related peptide, galanin, neurotensin and substance P was seen. At 12 h the peptide mRNA levels were still elevated and there was a concomitant increase in the number of peptide-immunoreactive cells. All peptide levels remained high for at least 48 h; however, 77 days after the antibody treatment only enkephalin-immunoreactive cells could be encountered. A disappearance of acetylcholinesterase- and enkephalin-immunoreactive cells could be encountered. A disappearance of acetylcholinesterase- and enkephalin-positive fibers was already seen 3 h after the antibody treatment, and after 24 h no fibers were encountered. In contrast, up until 48 h there was no apparent change in the number or intensity of immunofluorescent fibers expressing calcitonin gene-related peptide, galanin, neurotensin or substance P. However, 77 days after the antibody treatment the number of calcitonin gene-related peptide- and substance P-immunoreactive fibers was increased as compared to controls. In addition, reappearance of acetylcholinesterase- and enkephalin-immunoreactive fibers was seen 77 days after antibody administration, although their number was still low as compared to controls. Double-labeling immunohistochemistry revealed that the chromaffin cells expressing peptides after the antibody treatment preferentially were adrenaline storing cells (noradrenaline-negative). The majority of these cells expressed only one peptide. Both surgical transection of the splanchnic nerve as well as treatment with acetylcholine receptor antagonists mimicked the effects seen after the acetylcholinesterase-antibody treatment, although changes were less pronounced. The present results show that interruption of splanchnic transmission induces fast, marked, and selective increases in peptide expression in rat adrenal chromaffin cells.

Acetylcholinesterase↗
PubMed1990

Evidence for coexistence between calcitonin gene-related peptide and serotonin in the bulbospinal pathway in the monkey.

By the use of the indirect immunofluorescence and in situ hybridization techniques, the distribution of calcitonin gene-related peptide (CGRP)-like immunoreactivity (LI) and CGRP mRNA was studied in the spinal cord as well as in the midline raphe nuclei and the hypoglossal nucleus in the medulla oblongata of the monkey (Macaca fascicularis). In the spinal cord only a few large neurons in the motor nucleus contained CGRP-LI, while a majority of the neurons in the hypoglossal nucleus contained CGRP-LI. A relatively dense innervation by CGRP-immunoreactive (IR) fibers was also seen close to cell bodies and proximal dendrites of large neurons in the motor nucleus, especially in its ventral part. 5-Hydroxytryptamine (5-HT)-, substance P- and thyrotropin-releasing hormone (TRH)-IR varicosities were also observed in a similar position around large neurons in the motor nucleus. Double labeling disclosed that the majority of CGRP-IR axon terminals also contained 5-HT-LI. Expression of CGRP mRNA was found in neurons in the medullary midline raphe nuclei and in large neurons in the motor nucleus at the cervical spinal cord level. In adjacent sections of the medulla oblongata, CGRP-labeled neurons in the midline raphe nuclei also expressed preprotachykinin mRNA. The present results show that CGRP- and 5-HT-LI coexist in fibers within the motor nucleus of the monkey spinal cord and that this coexistence is probably due to the presence of CGRP in the descending bulbospinal, serotonergic pathway.

Animals↗
PubMed1990

Effects of central nervous system lesions on the expression of galanin: a comparative in situ hybridization and immunohistochemical study.

We have used in situ hybridization and immunohistochemistry to study the expression of galanin mRNA and galanin-like immunoreactivity after decortication and lesions of the ventral hippocampus. After decortication the levels of both galanin mRNA and galanin-like immunoreactivity were increased in the dorsal raphe nucleus. In addition, in decorticated rats, but not in controls, galanin mRNA could be seen in dorsal and ventral nuclei of the thalamus and in the remaining parts of the cortex. Increases in galanin mRNA and galanin-like immunoreactivity were also observed in the septum-vertical diagonal band after electrocoagulation lesions of the ventral hippocampus. In contrast, no changes were found after ibotenic acid lesions of the same hippocampal area. These results suggest that increases in the expression of galanin occur in certain neuron populations after direct lesion of their axons and/or terminal fields.

Animals↗
PubMed1989

Survival of adult 5-HT neurons following intraocular transplantation.

The present study was undertaken to provide an improved environment in which to examine the capacity of more mature CNS tissue to survive following transplantation. Tissue containing serotonin (5-HT) neurons from nucleus raphe dorsalis of 4- and 8-week-old rats was transplanted to the anterior chamber of the eye. Baseline conditions were improved by minimizing the time of the grafting procedure and enhancing the nutrition and oxygenation of the grafting medium. Additional treatment of the grafts during the 4 weeks of in oculo development included either: (1) intermittent hyperbaric oxygen (HBO), (2) continuous hyperoxia, or (3) control. In vivo measurement revealed that all grafts decreased significantly in size, a majority of which still demonstrated a small degree of vascularization. Microscopically, a significant percentage of the grafts demonstrated 5-HT-immunoreactive (5-HT-ir) fiber outgrowth into the host irides, although 5-HT-ir cell bodies could not always be discerned. In terms of percentage of grafts with surviving 5-HT-ir fibers, the best results were seen with the grafts treated with continuous hyperoxia (3 out of 4), as compared to HBO-treated grafts (4/18) and the control group (3/24). For both the HBO-treated and control groups, slightly better results were seen with 4-week-old vs 8-week-old donor tissue. The density and the surface area covered by the 5-HT-ir fibers was not correlated with either treatment or donor age. Thus, while continuous hyperoxia or HBO treatment may have a positive effect, the enhanced baseline conditions appear to provide an environment in which to demonstrate that 5-HT neurons from 4- and 8-week-old rats possess the capacity to survive transplantation.

Age Factors↗