Search PubMed⌕ Search

Biomedical subjects

M Parvinen

Publications and source records attributed to M Parvinen.

At least 109 records · Page 6Linked to original sources
PubMed1989

Interleukin-1 alpha stimulation of spermatogonial proliferation in vivo.

Interleukin-1 (IL-1) is a family of hormone-like polypeptides originally isolated from cultures of activated monocyte/macrophages and known to act as a potent mediator of inflammation (Dinarello 1984). The effects of IL-1 include augmentation of T and B lymphocyte proliferation (Oppenheim and Gery 1982), but also mitogenic effects on a wide variety of other cells such as fibroblasts (Libby et al. 1985), glial cells (Giulian and Lachman 1985), keratinocytes (Ristow 1987) and chondrocytes (Söder and Madsen 1988). Recent observations indicate that an IL-1-like factor with molecular characteristics similar to the macrophage-derived IL-1 alpha (March et al. 1985) is constitutively produced by the seminiferous tubules (Khan et al. 1987). The present data show that recombinant IL-1 alpha (rIL-1 alpha) stimulates DNA synthesis in intermediate and type B spermatogonia in vivo and suggest that IL-1 alpha may act as a growth factor for spermatogonia.

Animals↗
PubMed1989

Stage-specific expression of nucleoprotein mRNAs during rat and mouse spermiogenesis.

The expression of mRNAs for a transition protein (TP1) and two variants of protamines (P1 and P2) during rat and mouse spermiogenesis was investigated using cDNA hybridization techniques. Slot-blot analyses from 1-mm segments of seminiferous tubules and in situ hybridization from testis sections showed that the levels of mRNA for TP1 increased in step-7 round spermatids at substage VIIb of the seminiferous epithelial cycle, earlier than that of P1 and P2 at substage VIIc. The mRNA levels of all transcripts remained high during steps 8-13 in both species. In the rat, the mRNA of TP1 disappeared during step 14 between substages XIVa and XIVb. The P1 mRNA levels decreased during steps 15-16 (stages I-III) and the P2 mRNA during step 15 (stage I). In the mouse, TP1 mRNA disappeared during step 13 (stage I). The P1 mRNA level decreased before P2 in step 14 (stage II), whereas P2 was detected up to step 15 (stage V). Northern-blot analyses with all three cDNA probes revealed two sizes of mRNA and their stage-specific expression. The shorter transcripts appeared later than the longer ones, at the steps of spermiogenesis where translation is known to begin. The results suggest that transcription of TP1, P1, and P2 mRNAs starts at specifically defined times during spermiogenesis and that the temporal translational regulation of these mRNAs is different.

Animals↗
PubMed1989

Developmental and differential expression of the ornithine decarboxylase gene in rodent testis.

Ornithine decarboxylase (ODCase) is the first and rate-limiting enzyme in the polyamine biosynthetic pathway and it is androgen regulated in the mouse. The expression of ODCase transcripts during testicular development was examined by Northern blot analysis with a mouse ODCase cDNA probe. Total RNA was isolated from the testes of prepubertal mice at 6, 8, 12, 16, 18, 20, 22, and 30 days of age, from enriched populations of germinal cells obtained from the testis of immature (8 days old) and mature (45 days old) mice and from several mouse somatic tissues. The level of the two ODCase transcripts (2.2 and 2.7 kilobases) was low but detectable in the testes of 6- to 16-day-old mice and increased substantially as the first spermatogenic wave proceeded into spermiogenesis. The low ODCase mRNA levels observed in prepubertal mouse testes were confirmed with RNA samples obtained from enriched germ cell populations of type A and type B spermatogonia and interstitial cells obtained from Day 8 mouse testes. In agreement with the developmental studies, ODCase mRNA levels increased substantially in enriched populations of pachytene spermatocytes, round spermatids, and residual bodies/cytoplasts isolated from mature testes. Similar results were obtained by in situ hybridization of sections of rat testes. Reduced levels of ODCase transcripts were detected in RNA obtained from cultured mouse Sertoli cells obtained from the testes of 21-day-old mice and in RNA from liver, brain, heart, spleen, seminal vesicle, and aorta. In contrast, ODCase transcript levels from kidneys of male mice were as high as those detected in testis RNA. Substantial levels of ODCase mRNAs were also found in the epididymis. Analysis of polysome gradients prepared from total testis extracts revealed a distribution of ODCase mRNA in both nonpolysomal and polysomal fractions of the gradient, suggesting that ODCase is translationally regulated in the mouse testis.

Animals↗
PubMed1989

Regulation of urokinase- and tissue-type plasminogen activator gene expression in the rat seminiferous epithelium.

The secretion of plasminogen activator by seminiferous tubules at defined stages of the epithelial cycle is influenced both by neighboring spermatogenic cells and by hormones. We have used cRNA probes for urokinase-type (uPA) and tissue-type (tPA) plasminogen activators to analyze their mRNA levels in different stages of the epithelial cycle. Urokinase-type PA mRNA was most abundant in stages VII-VIII, while tPA mRNA levels showed smaller variations between the different stages. Both FSH and (Bu)2cAMP increased the steady-state level of tPA mRNA and tPA production without affecting those of uPA in stages VII-IX in vitro, whereas retinoic acid treatment selectively increased the concentration uPA mRNA and uPA production in stages II-VI. The results show that the expression of the uPA and tPA genes is differentially regulated in specific stages of the rat seminiferous epithelium.

Animals↗
PubMed1988

Immunohistochemical localization of urokinase-type plasminogen activator in Sertoli cells and tissue-type plasminogen activator in spermatogenic cells in the rat seminiferous epithelium.

The occurrence of plasminogen activators of the urokinase-type (u-PA) and tissue-type (t-PA) at various stages of the epithelial cycle was studied immunohistochemically in rat seminiferous tubule segments. u-PA immunoreactivity was detected exclusively at stages VII and VIII in Sertoli cells, displaying a distinct granular cytoplasmic staining. t-PA immunoreactivity was found during mid- and late pachytene and diakinesis (stages VII-XIII) in spermatogenic cells, displaying a granular cytoplasmic staining with maximal intensity in stages IX-XIII. The specificity of the stainings was supported by staining controls, including absorption of the antibodies with purified preparations of the activators. It was also supported by zymographic studies of the occurrence of u-PA and t-PA in extracts of tubular segments at different stages of the cycle, isolated by transillumination-assisted microdissection. The possible functions of the two types of plasminogen activators in the seminiferous epithelium are discussed.

Animals↗
PubMed1988

Mutagenicity of gossypol analyzed by induction of meiotic micronuclei in vitro.

Chromosome breakage caused by mutagens in male germ cells can be analyzed by micronucleus induction during meiotic division. This can be followed in vitro by culturing seminiferous tubular segments from stages of the epithelial cycle that contain late pachytene and diakinetic primary spermatocytes. We studied the mutagenic potential of a male contraceptive, gossypol, in this test system using adriamycin (10 ng/ml) as a reference mutagen. A small but significant increase in the frequency of micronuclei was induced with concentrations of 10 and 20 micrograms/ml of gossypol, while cytotoxic effects appeared at concentration of 20 micrograms/ml and were evident at 50 micrograms/ml. Analysis of meiotic micronucleus induction in vitro seems to be a sensitive test system of male germ-cell mutagenesis, but further studies on the possible mutagenic effects of gossypol are needed.

Animals↗
PubMed1988

Localization of protamine 1 mRNA in different stages of the cycle of the rat seminiferous epithelium.

A mouse protamine 1 cDNA probe was used to study P1 protamine gene expression during the cycle of the seminiferous epithelium in the rat. In situ hybridization experiments showed that transcription of the P1 protamine mRNA starts in the middle of step 7 of spermiogenesis during substage VIIc. The mRNA levels stay high in steps 7-14 spermatids but decrease during steps 15-16 and are virtually undetectable in steps 17-19 spermatids. Northern blot analyses of RNAs isolated from microdissected pools of seminiferous tubules show high P1 protamine mRNA concentrations during stages VIIc-XIV-III of the cycle and lower levels during stages IV-VIIb. Owing to a post-transcriptional shortening of the poly(A) tail by 130 bases, a decrease in the size of protamine 1 mRNA from approximately 580 to 450 nucleotides was observed in stages XIII-XIV suggesting an initiation of protamine 1 synthesis in step 13-14 spermatids. In stages II-VI (steps 16-18 spermatids), only the smaller size protamine 1 mRNA was detectable. The expression of protamine 1 mRNAs has been localized in the very last phase of the haploid gene activity. Although the in situ hybridization suggests a disappearance of protamine 1 mRNA after step 16 of spermiogenesis, Northern blot analysis shows that low levels of mRNA are present during the period of final condensation of the chromatin, reflecting the association of protamine with DNA.

Animals↗
PubMed1988

Expression of a testis-specific hsp70 gene-related RNA in defined stages of rat seminiferous epithelium.

Changes in the level of a testis-specific hsp70 gene-related transcript (hst70 RNA) and its cellular localization during the cycle of rat seminiferous epithelium have been investigated. Segments of seminiferous tubules at defined stages of the cycle were isolated in living condition by transillumination-assisted microdissection and the exact stages identified by phase-contrast microscopy of live cell squashes. The levels of the hst70 RNA were determined by Northern and slot blotting of whole cell lysates. High levels were found in stages XII-XIV and I to early VII of the cycle, and low levels were found in other stages, i.e., late VII (VIId) through VIII-XI of the cycle. The in situ hybridization revealed that the hst70 gene was activated in late pachytene primary spermatocytes during stage XII of the cycle, and that mRNA was then present in cells during differentiation through diakinesis, meiotic divisions, and early spermiogenesis (steps 1 through early 7). The activation of the gene coding for hst70 RNA shortly before meiotic divisions may indicate that the gene product is needed either during differentiation of late spermatocytes into spermatids or later during spermiogenesis, and that the mRNA may be stored in early spermatids.

Animals↗
PubMed1988

Histological and functional changes of the testis tissue during GnRH agonist treatment of prostatic cancer.

The purpose of this study was to examine long-term effects of GnRH agonists on human testicular histology and endocrine function. Patients with advanced prostate cancer (n = 7) were treated with the potent GnRH agonist analogue buserelin (Bu, Hoechst), 600 micrograms X 3/day intranasally. After 6 months, the patients were orchiectomized, and the testis tissue was used for histological studies and measurements of endocrine function in vitro. Fourteen other patients with matching ages and extent of the disease were castrated as the first form of therapy, and their testis tissue was used as controls (C). Severe atrophy of seminiferous tubules was seen in light microscopy in the testes of the Bu treated patients. Many tubules showed only Sertoli cells, and the seminiferous epithelium was frequently absent. In contrast, no clear changes were seen in the number of Leydig cells. Testicular content of testosterone (T) decreased greater than 95% by Bu treatment: C = 1.5 +/- 0.2 nmol/g wet wt (x +/- SE); Bu = 0.070 +/- 0.019 nmol/g. Likewise, a drop of 80% occurred in testicular high affinity receptors for FSH: C = 0.37 +/- 0.019 pmol/g; Bu = 0.067 +/- 0.009 pmol/g. In contrast, the number of LH receptors was unaffected by the treatment, C = 0.18 +/- 0.033; Bu = 0.18 +/- 0.032 pmol/g. When testis slices were incubated in the presence of maximally stimulating concentration of hCG (100 ng/ml), both groups of tissue responded similarly with a 50% increase in T production, albeit the absolute production rate was reduced by 95% in the Bu group. When several steroid precursors of T were analyzed in the incubation media, it appeared that decreased androgen synthesis was most clearly due to decreased 3 beta-hydroxysteroid dehydrogenase activity. It is concluded that long-term treatment with GnRH agonists in prostatic cancer patients brings about dramatic damage of seminiferous tubular function and reduces testicular androgen producing capacity, but has no effect on testicular capability of responding immediately to LH stimulation.

Aged↗
PubMed1987

Distribution and activation of protein kinase C in the rat testis tissue.

The distribution and role of the calcium-activated, phospholipid-dependent protein kinase C (PK-C) was studied in rat testis. When testis tissue was homogenized in the presence of 2 mmol/l EDTA and EGTA, the majority (greater than 70%) of the PK-C activity was soluble, the rest was released from the particulate fraction by solubilization with 0.3% Triton X-100. Without chelating agents the soluble PK-C activity was undetectable, and only partially recovered from solubilized membranes. Preincubation of the tissue with the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA, 10(-7) mol/l) translocated PK-C to the membranes, and the majority of this activity was recovered by solubilization. Mobility of testicular soluble PK-C activity in HPLC-DEAE cellulose chromatography was similar to that of the brain enzyme. This single step purified testicular PK-C activity 140-fold. The specific activity and subcellular distribution of PK-C was similar in whole testis tissue and separated seminiferous tubules (160-210 pmol 32P X mg protein-1 X min-1 in the soluble and particulate fractions), but 2- to 3-fold higher in purified Leydig cells. However, the majority of total testicular PK-C activity appeared to be of tubular origin. Unilateral cryptorchidism for 1 week reduced PK-C of the abdominal testis by 50%, and the activity of dissected seminiferous tubules varied according to the epithelial wave. Both findings suggest that the bulk of the activity resides in the seminiferous epithelium. Involvement of PK-C in Leydig cell function was demonstrated using the TPA, which at 10(-7) mol/l inhibited basal cAMP production by 50% (P less than 0.01) but increased that of testosterone by 2- to 3-fold (P less than 0.01). On the other hand, when incubated with hCG, TPA inhibited both cAMP and testosterone production; the ED50s of hCG stimulation increased 4- to 10-fold with both parameters. It is concluded that PK-C activity is present in both the seminiferous tubules and Leydig cells, and is involved in the regulation of these testicular compartments. Its total activity and subcellular distribution are at variance according to the functional state and endocrine milieu of the testis.

Animals↗
PubMed1987

Stage-specific regulation of plasminogen activator secretion in the rat seminiferous epithelium.

The cyclic secretion of plasminogen activator (PA) by Sertoli cells in stages VII and VIII of the rat seminiferous epithelial cycle is influenced by hormones and adjacent spermatogenic cells. To understand this interaction more in detail, we have analyzed the effects of FSH, (Bu)2cAMP, testosterone, insulin, and retinoic acid (RA) on staged seminiferous tubule segments in vitro. FSH stimulated stages VIIcd to XI of the cycle; similar results were obtained with (BU)2cAMP. RA stimulated PA secretion in stages I-VIIab, but testosterone and insulin had no effect in any stage. The secreted PA was mainly of the urokinase type, although small amounts of the tissue-type PA were found after stimulation by FSH and cAMP. These results suggest that spermatogenic cells modify the responsiveness of Sertoli cells to hormonal stimulation. Stages I-VIIab are sensitive to stimulation by RA whereas stages VIIcd-XI are preferentially stimulated by FSH and (Bu)2cAMP.

Animals↗
PubMed1986

Expression of acrosin during mouse spermatogenesis: a biochemical and immunocytochemical analysis by a monoclonal antibody C 11 H.

A monoclonal antibody C 11 H was produced against human acrosomal antigen. It also cross-reacted with acrosomes of the boar and the mouse. In boar spermatozoa the antibody reacted, in immunoblotting analysis, with polypeptides of Mr 55,000 and 53,000. The proteolytic activity was detected by zymographic casein overlay assay. Partially purified boar sperm acrosin was bound by the C 11 H affinity column, and acrosin activity was detected in the eluate. These experiments indicate that C 11 H antibody recognizes sperm acrosin. The acrosin expression during spermatogenesis was studied with C 11 H antibody, using mouse testis as a model. Immunocytochemical analysis revealed that step 9 spermatids were the first cells to react with C 11 H antibody. During step 14, the perinuclear pattern of C 11 H-binding disintegrated into small particles around the spermatid nuclei for the period of close association between spermatid bundles and Sertoli cells. During late step 15, the antigen became located at the site in the acrosome typical for step 16 spermatids and spermatozoa. These results indicate that monoclonal C 11 H antibody recognizes acrosin that is first expressed in haploid cells coincident with the onset of nuclear elongation and cessation of RNA transcription. The changes in the distribution pattern suggest that acrosin may be modified by Sertoli cells. In addition to studies on acrosin, this antibody may be useful in investigations of transcription and translation and their regulation during spermatogenesis in general.

Acrosin↗
PubMed1986

Testicular plasminogen activators during postnatal development in the rat.

In the seminiferous epithelium, Sertoli cells secrete plasminogen activator (PA) under regulation of follicle stimulating hormone, cyclic AMP and neighbouring spermatogenic cells. Recent observations suggest that preleptotene spermatocytes upon their release from the basement membrane of the seminiferous tubule are important regulators of PA secretion. To study further the role of PA's in the seminiferous tubules, we have analyzed the endogenous levels and secretion rates of PA at various ages during postnatal development, and performed biochemical analyses of the types of PA in the testis and spent media from seminiferous tubular cultures. Cyclic secretion of PA started at the age of 28 days, and from 40 days onwards, the high secretion rates were localized in stages VII and VIII of the cycle of the seminiferous epithelium. The secreted PA is most obviously of the urokinase type; both urokinase-type and tissue-type PA-like activities were found in seminiferous tubular homogenates. The increase in testicular PA levels concomitant to the onset of meiosis in the epithelium was due to the urokinase-type PA-like activity.

Aging↗
PubMed1986

Testicular aspiration biopsy in evaluation of fertility of mink (Mustela vison).

A 19-gauge needle biopsy was taken of the testis of mink in late January. When scores from 1 to 10 were given according to the developmental stage and number of spermatogenic cells, males scoring 8-10 returned significantly better breeding results than did males having scores less than 7. The biopsy did not affect libido or induce other disturbances of fertility. Fine-needle aspiration biopsy of the testis is possibly the most convenient and accurate infertility assay in mink breeding.

Animals↗
PubMed1986

Regulation of stages VI and VIII of the rat seminiferous epithelial cycle in vitro.

Plasminogen activator (PA) is secreted cyclically (in stages VII and VIII) by rat seminiferous tubules. To investigate whether this can be maintained and influenced in vitro, tubule segments from stages VI and VIII of the epithelial cycle were cultured for 3 days in chemically defined medium supplemented with testosterone, FSH, or a combination of testosterone, FSH, insulin and retinoic acid (4F). Morphological and flow cytometric analyses of stage VI tubules suggested a roughly normal differentiation to stage VIII. They developed an increased PA secretion on day 3 of culture. Stage VIII tubules, however, did not develop all the characteristics of stage XII. Step 8 spermatids did not elongate and step 19 spermatids failed to develop into spermatozoa. Secretion of PA on day 3 was not significantly different to that on day 1. The 4F combination very significantly stimulated PA secretion in both stages, but FSH alone was effective only in stage VIII. Most of the secreted PA had a molecular weight of 43,000 in both stages, suggesting that it is of urokinase type. The results suggest that stage VI is more able to differentiate in vitro for 3 days than stage VIII; the cyclic secretion pattern of PA was partially maintained in tubule segments from stage VI. Follicle-stimulating hormone had an effect on PA secretion only in stage VIII, whereas the 4F combination was stimulatory in both stages. The retinoic acid in this combination may be of importance in the regulation of PA secretion by seminiferous tubules.

Animals↗
PubMed1986

Cell interactions in the rat seminiferous epithelium with special reference to the cellular distribution of calmodulin.

Spermatogenesis is dependent on stimulation by pituitary gonadotropins, FSH and LH. Targets for these hormones are Sertoli and Leydig cells, respectively. The effect of LH on spermatogenesis is mediated by testosterone. In addition to hormones, interactions between neighbouring cells seem to regulate spermatogenesis. This is reflected by cyclic secretion of several proteins by the seminiferous epithelium, of which plasminogen activator is a good example. While it is controlled by FSH a factor in preleptotene spermatocytes may also influence its cyclic secretion pattern. Both testosterone and FSH have a cyclic action in the seminiferous epithelium. The androgens seem to predominate in stages where spermiation, onset of meiosis and the highest rate of RNA transcription occur (VII-XI). FSH is most active in stages that contain meiotic divisions and early spermiogenesis (XIII-V), greatly stimulating the production of cyclic AMP. To investigate further the "second messengers" of FSH action in the seminiferous epithelium, the cellular distribution of calmodulin was analyzed using an indirect immunocytochemical method. In addition to their clear cyclic distribution in primary spermatocytes and in spermatids, Sertoli cells also showed a bright calmodulin immunofluorescence that was apparently cyclic. These observations suggest a local calmodulin and calcium regulation of spermatogenesis.

Androgens↗