Effects and interactions of LH and LHRH agonist on testicular morphology and function in hypophysectomized rats

The effects of single or combined daily treatment with an LHRH agonist and low or high doses of LH upon the testes of adult hypophysectomized rats were studied for up to 2 weeks in which changes in testicular histology, particularly the interstitial tissue, were examined by morphometry and related to functional assessment of the Leydig cells in vivo and in vitro. Compared to saline-treated controls, LHRH agonist treatment did not alter testis volume or the composition of the seminiferous epithelium or any of the interstitial tissue components although serum testosterone and in-vitro testosterone production by isolated Leydig cells were significantly reduced. With 2 micrograms LH for treatment, testis volume was increased, spermatogenesis was qualitatively normal, total Leydig cell volume was increased, serum testosterone values were initially elevated but subsequently declined and in-vitro testosterone production was enhanced. Testis volume with 20 micrograms LH treatment was unchanged compared to saline treatment, the seminiferous epithelium exhibited severe disruption but total Leydig cell volume was greatly increased due to interstitial cell hyperplasia. This group showed elevated serum testosterone concentrations and major increases in testosterone production in vitro. Treatment with LHRH agonist with either dose of LH resulted in reduced testis volume, moderate to very severe focal spermatogenic disruption and increased total Leydig cell volume although serum testosterone values and in-vitro testosterone production were markedly reduced compared to control rats. It is concluded that, in the absence of the pituitary, LHRH agonist fails to disrupt spermatogenesis and the previously described antitesticular action of LHRH agonists in intact rats is therefore dependent upon the presence of LH, which alone or in combination with LHRH agonist, may focally disrupt spermatogenesis in hypophysectomized rats whereas the Leydig cells undergo hyperplasia. The findings show that impairment of spermatogenesis is accompanied by alterations of the interstitial tissue and suggest that communication between these two compartments is involved in the regulation of testicular function.     

Resonance Raman investigation of CO-ligated monomeric insect hemoglobins. Direct evidence for reciprocal changes in iron-axial ligand bonds induced by allosteric transitions

The resonance Raman spectra of the two affinity states of the CO-ligated monomeric insect hemoglobins, Chironomus thummi thummi (CTT) III ad IV, have been investigated. We have identified (via 54Fe/57Fe and 13C18O/12C16O isotope exchange) the Fe-N epsilon(His) stretching mode at approximately 317 cm-1. This stretching mode changes from 329 (pH 5.5) to 317 cm-1 (pH 9.5) reflecting the pH-induced t in equilibrium with r conformational transition. The Fe-CO stretching mode is also pH-sensitive changing from 483 (pH 5.2) to 485 cm-1 (pH 9.2) in 57Fe CTT III . 13C18O complex. However the C-O stretching mode is pH-insensitive. The nonallosteric monomeric insect hemoglobin CTT I does not exhibit a pH-dependence of these vibrational modes. pH-Induced effects were also observed for a vinyl bending mode at 379 cm-1 (pH 9.5) in CTT III deuterated at the beta-carbons of the vinyls in position 2 and 4. It shifts to 390 cm-1 at pH 5.5. The other vinyl vibration at 573 cm-1 exhibits intensity enhancement via through-space coupling with the Fe-C-O bending mode. Our resonance Raman data provide the first direct evidence that the trans-effect is operative as a trigger mechanism for ligand-binding in monomeric allosteric insect hemoglobins. In going from the low-affinity to the high-affinity state, the Fe-N epsilon(His) bond becomes weaker, whereas the Fe-CO bond becomes stronger.     

Endogenous Rhythms in Photosynthesis, Sucrose Phosphate Synthase Activity, and Stomatal Resistance in Leaves of Soybean (Glycine max [L.] Merr.)

Experiments were conducted with soybean (Glycine max [L.] Merr. cv `Ransom') plants to determine if diurnal rhythms in net carbon dioxide exchange rate (CER), stomatal resistance, and sucrose-phosphate synthase (SPS) activity persisted in constant environmental conditions (constant light, LL; constant dark DD) and to assess the importance of these rhythms to the production of nonstructural carbohydrates (starch, sucrose, and hexose). Rhythms in CER, stomatal resistance, and SPS activity were observed in constant environmental conditions but the rhythms differed in period length, amplitude, and phase. The results indicated that these photosynthetic parameters are not controlled in a coordinated manner. The activity of UDPG pyrophosphorylase, another enzyme involved in sucrose formation, did not fluctuate rhythmically in constant conditions but increased with time in plants in LL. In LL, the rhythm in CER was correlated positively with fluctuations in total chlorophyll (r = 0.810) and chlorophyll a (r = 0.791) concentrations which suggested that changes in pigment concentration were associated with, but not necessarily the underlying mechanism of, the rhythm in photosynthetic rate. Assimilate export rate, net starch accumulation rate, and leaf sucrose concentration also fluctuated in constant light. No single photosynthetic parameter was closely correlated with fluctuations in assimilate export during LL; thus, assimilate export may have been controlled by interactions among the endogenous rhythms in CER, SPS activity, or other metabolic factors which were not measured in the present study.     

Virulence properties of strains of agrobacterium on the apical and Basal surfaces of carrot root discs

Most pathogenic strains of Agrobacterium are able to induce crown gall or hairy root on both the apical surface (facing the root tip) and the basal surface (facing the shoot) of carrot (Daucus carota L.) root discs. Tumorigenic strains carrying mutations in the shoot inhibition region of the T-DNA (TL-DNA genes 1 and 2) are markedly attenuated on the basal surface but remain virulent on the apical surface. Coinoculation of two attenuated tumorigenic strains, with mutations in gene 1 and gene 2, respectively, resulted in restoration of virulence on the basal surface. Wild type hairy root-inducing strains can be divided into two groups: those that are virulent on both apical and basal surfaces and those that are virulent only on the apical surface. α-Naphthalene acetic acid stimulated virulence of hairy root strain TR7, belonging to the latter group, on the basal surface. Attenuated virulence on the basal surface can be explained in terms of an auxin deficiency in the basal tissues and unidirectional auxin transport to the apical surface.     

Conus geographus toxins that discriminate between neuronal and muscle sodium channels

We describe the properties of a family of 22-amino acid peptides, the mu-conotoxins, which are useful probes for investigating voltage-dependent sodium channels of excitable tissues. The mu-conotoxins are present in the venom of the piscivorous marine snail, Conus geographus L. We have purified seven homologs of the mu-conotoxin set and determined their amino acid sequences, as follows, where Hyp = trans-4-hydroxyproline. GIIIA R.D.C.C.T.Hyp.Hyp.K.K.C.K.D.R.Q.C.K.Hyp.Q.R.C.C.A-NH2 [Pro6]GIIIA R.D.C.C. T.P.Hyp.K.K.C.K.D.R.Q.C.K.Hyp.Q.R.C.C.A-NH2 [Pro7]GIIIA R.D.C.C.T.Hyp.P.K.K.C.K.D.R.Q.C.R.Hyp.Q.R.C.C.A-NH2 GIIIB R.D.C.C.T.Hyp.Hyp.R.K.C.K.D.R.R.C.K.Hyp.M.K.C.C.A-NH2 [Pro6]GIIIB R.D.C.C.T.P.Hyp.R.K.C.K.D.R.R. C.K.Hyp.M.K.C.C.A-NH2 [Pro7]GIIIB R.D.C.C.T.Hyp.P.R.K.C.K.D.R.R.C.K.Hyp.M.K.C.C.A-NH2 GIIIC R.D.C.C.T.Hyp.Hyp.K.K.C.K.D.R.R.C.K.Hyp.L.K.C.C.A-NH2. Using the major peptide (GIIIA) in electrophysiological studies on nerve-muscle preparations and in single channel studies using planar lipid bilayers, we have established that the toxin blocks muscle sodium channels, while having no discernible effect on nerve or brain sodium channels. In bilayers the blocking kinetics of GIIIA were derived by statistical analysis of discrete transitions between blocked and unblocked states of batrachotoxin-activated sodium channels from rat muscle. The kinetics conform to a single-site, reversible binding equilibrium with a voltage-dependent binding constant. The measured value of the equilibrium KD for GIIIA is 100 nM at OmV, decreasing e-fold/34 mV of hyperpolarization. This voltage dependence of blocking is similar to that of tetrodotoxin and saxitoxin as measured by the same technique. The tissue specificity and kinetic characteristics suggest that the mu-conotoxins may serve as useful ligands to distinguish sodium channel subtypes in different tissues.     

Analogue inhibitor of 2-5A action: effect on the interferon-mediated inhibition of encephalomyocarditis virus replication.

Chemically synthesised CH3Sp(A2'p)2A2'pp3'OCH3 has been used to assess the importance of the ppp(A2'p)nA (n greater than or equal to 2: 2-5A) system in the antiviral action of interferon against encephalomyocarditis virus (EMC). It inhibits activation of the 2-5A-dependent RNase by 2-5A in intact mouse L929 cells and cell-free systems. In interferon-treated, EMC-infected L929 cells it inhibits 2-5A-mediated rRNA cleavage and partially restores EMC RNA synthesis and virus yield. Activation of the 2-5A-dependent RNase must, therefore, play some part in interferon action against the growth of EMC virus in such cells.     

1-Methylguanine and 7-methylguanine increase cell agglutinability

Summary 1-Methylguanine and 7-methylguanine, both metabolic products of tRNA degradation, are known to induce transformation of Chinese hamster fibroblasts in culture. The effects of these compounds on the cell membrane have been studied by the method of Concanavalin A-mediated hemadsorption. 1-Methylguanine or 7-methylguanine induced a 50% increase of Con A-mediated hemadsorption within 20 hours of exposure of the cells to the agent at a concentration of 10^-5 M. This alteration was reversed within 13 days when the cells were grown in the control medium. Prolonged treatment with 1-methylguanine or 7-methylguanine resulted in changes which were only slowly reversed during growth of the cells in the control medium. The effect of the methylated purines on the cell membrane could be completely inhibited by simultaneous addition of dibutyryl-cAMP at a concentration of 10^-5 M. The possible mechanism of cell membrane alteration by methylated purines and its relevance to transformation in vitro are discussed.     

Value of routine follow up of women treated for early carcinoma of the breast.

The value of routine follow up of women treated for early breast cancer by mastectomy with or without postoperative radiotherapy was assessed retrospectively. Over eight years 546 patients made 6863 clinic visits, during which 192 first relapses were detected. Ninety three relapses were detected at scheduled (routine) visits and 99 at unscheduled (interval) visits. First relapses within the treated area or in the contralateral breast were detected significantly more commonly at routine visits than were first metastatic relapses (66/89 (74%) compared with 27/103 (26%)). Patients whose local relapse was detected at a routine visit had a significantly better survival than those whose local relapse was detected at an interval visit. A relapse that was potentially curable (local or in the contralateral breast) was detected at 66 (1%) of 6764 routine visits, but only 26 (39%) of these patients remained free of disease. It is concluded that the intensity of follow up of such patients could be reduced without any adverse effect on prognosis but with appreciable financial and other benefits.     

Regeneration of Leydig cells in unilaterally cryptorchid rats: evidence for stimulation by local testicular factors

Summary Leydig cells in testes of adult rats were selectively destroyed by a single intraperitoneal injection of ethane dimethane sulphonate. Four days later rats were made unilaterally cryptorchid and 1, 2 and 4 weeks later the histology of the testes was examined by light microscopy and morphometry. After induction of unilateral cryptorchidism, the volume of abdominal compared to scrotal testes was reduced by 45–60% due to rapid impairment of spermatogenesis in abdominal testes. Leydig cells were not present in either scrotal or abdominal testes in the 1-week unilateral crytorchid group. A new generation of foetal-type Leydig cells was observed in scrotal testes of the 2-week unilateral crytorchid group although their total volume per testis estimated by morphometry, was small, being approximately 1 l. In contrast, the abdominal testis exhibited a remarkable proliferation of foetal-type Leydig cells (total volume per testis, 16 l) which predominantly surrounded the peritubular tissues of the seminiferous tubules. A similar morphology and pattern of Leydig cell development was observed in scrotal and abdominal testes of the 4-week unilateral cryptorchid group where total Leydig cell volume was 7 l vs 21 l, respectively. The results show that regeneration of a new population of Leydig cells occurs more rapidly in the abdominal testis than in the scrotal testis of the same animal. These observations suggest the possibility that augmentation of Leydig cell growth is mediated by local intratesticular stimulatory factors within the abdominal testis. Development of new Leydig cells from the peritubular tissue provides circumstantial evidence that the seminiferous tubules and in particular the Sertoli cells, are a likely source of agents that stimulate the growth of Leydig cells.