Molecular dynamics simulations of mixed lubrication with smooth particle post-processing

A post-processing method for molecular dynamics (MD) simulations of friction based on the smooth particle approach is proposed, allowing--among other features--the introduction and evaluation of a solid-solid contact area arising due to direct asperity interaction. In order to illustrate the feasibility of this scheme, a large number of MD calculations of lubricated nanotribological systems with various asperity geometries and carefully selected numbers of lubricant molecules were carried out and analysed. In this manner, it is shown that the friction force as a function of load agrees very well with a three-parameter friction law which, in addition to the adhesion- and the load-controlled terms, contains a load-independent offset.

High island densities in pulsed laser deposition: causes and implications

By studying metal growth on Pt(111), we determine the reasons for the high island densities observed in pulsed laser deposition (PLD) compared to conventional thermal deposition. For homoepitaxy by PLD with moderate energies ( < or approximately 100 eV) of the deposited ions, high island densities are caused by the high instantaneous flux of arriving particles. Additional nuclei are formed at high ion energies (> or approximately 200 eV) by adatoms created by the impinging ions. For heteroepitaxy, the island density is also increased by intermixing (deposited material implanted in the surface), creating an inhomogeneous potential energy surface for diffusing atoms. We discuss implications for layer-by-layer growth and sputter deposition.

Creation of nanohillocks on CaF2 surfaces by single slow highly charged ions

Upon impact on a solid surface, the potential energy stored in slow highly charged ions is primarily deposited into the electronic system of the target. By decelerating the projectile ions to kinetic energies as low as 150 x q eV, we find first unambiguous experimental evidence that potential energy alone is sufficient to cause permanent nanosized hillocks on the (111) surface of a CaF(2) single crystal. Our investigations reveal a surprisingly sharp and well-defined threshold of potential energy for hillock formation which can be linked to a solid-liquid phase transition.

Tree internal signalling and defence reactions under ozone exposure in sun and shade leaves of European beech (Fagus sylvatica L.) trees

The influence of free-air ozone (O(3)) fumigation on the levels of gene transcripts and compounds of defence and signalling were analysed in leaves of adult beech trees from the "Kranzberg Forest" research site in 2003 and 2004. This includes the precursor of the stress hormone ethylene, ACC (1-aminocyclopropane-1-carboxylic acid), conjugated salicylic acid, lignin content as well as of the expression level of genes connected with oxidative stress and stress signalling. At this site mature beech trees were exposed to an enhanced O(3) regime by a free-air O(3) canopy exposure system. Levels of conjugated ACC and conjugated salicylic acid in leaves were increased under O (3) fumigation whereas lignin content was only slightly enhanced. Quantitative real-time RT-PCR (qRT-PCR) was performed on transcripts of genes connected with lignin, salicylic acid, and ethylene formation, the shikimate pathway, abscisic acid biosynthesis as well as with the antioxidative system. Genes which showed O(3)-dependent increases included FSCOMT (caffeic-acid O-methyltransferase) connected with lignin formation, the stress response genes FSACS2 (ACC synthase) and FSPR1 (PR10 - pathogenesis-related protein), as well as FSNCED1 (9-cis-epoxicarotenoid dioxygenase), the rate-limiting enzyme of the ABA synthesis. For FSNCED1 expression level, a significant O(3) effect was found with an 8-fold (sun) and 7-fold (shade) induction in July 2003 and a 3-fold and 2.5-fold induction in July 2004. While the observed effects were not continuous, elevated O(3) is concluded to have the potential to disrupt the defence and signalling system.

Beech leaf colonization by the endophyte Apiognomonia errabunda dramatically depends on light exposure and climatic conditions

Ozone and light effects on endophytic colonization by Apiognomonia errabunda of adult beech trees (Fagus sylvatica) and their putative mediation by internal defence compounds were studied at the Kranzberg Forest free-air ozone fumigation site. A. errabunda colonization was quantified by "real-time PCR" (QPCR). A. errabunda-specific primers allowed detection without interference by DNA from European beech and several species of common genera of plant pathogenic fungi, such as Mycosphaerella, Alternaria, Botrytis, and Fusarium. Colonization levels of sun and shade leaves of European beech trees exposed either to ambient or twice ambient ozone regimes were determined. Colonization was significantly higher in shade compared to sun leaves. Ozone exhibited a marginally inhibitory effect on fungal colonization only in young leaves in 2002. The hot and dry summer of 2003 reduced fungal colonization dramatically, being more pronounced than ozone treatment or sun exposure. Levels of soluble and cell wall-bound phenolic compounds were approximately twice as high in sun than in shade leaves. Acylated flavonol 3- O-glycosides with putatively high UV-B shielding effect were very low in shade canopy leaves. Ozone had only a minor influence on secondary metabolites in sun leaves. It slightly increased kaempferol 3- O-glucoside levels exclusively in shade leaves. The frequently prominent hydroxycinnamic acid derivative, chlorogenic acid, was tested for its growth inhibiting activity against Apiognomonia and showed an IC50 of approximately 8 mM. Appearance of Apiognomonia-related necroses strongly correlated with the occurrence of the stress metabolite, 3,3',4,4'-tetramethoxybiphenyl. Infection success of Apiognomonia was highly dependent on light exposure, presumably affected by the endogenous levels of constitutive phenolic compounds. Ozone exerted only minor modulating effects, whereas climatic factors, such as pronounced heat periods and drought, were dramatically overriding.

Transcriptome analysis of ozone-responsive genes in leaves of European beech (Fagus sylvatica L.)

Suppression subtractive hybridization (SSH) was performed to isolate cDNAs representing genes that are differentially expressed in leaves of Fagus sylvatica upon ozone exposure. 1248 expressed sequence tags (ESTs) were obtained from 2 subtractive libraries containing early and late ozone-responsive genes. Sequences of 1139 clones (91 %) matched the EBI/NCBI database entries. For 578 clones, no putative function could be assigned. Most abundant transcripts were O-methyltransferases, representing 7 % of all sequenced clones. ESTs were organized into 12 functional categories according to the MIPS database. Among them, 12 % (early)/15 % (late) were associated with disease and defence, 19/11 % with cell structure, 4/10 % with signal transduction, and 9/6 % with transcription. The expression pattern of selected ESTs (ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit [rbcS], WRKY-type transcription factor, ultraviolet-B-repressible protein, aquaporine, glutathione S-transferase, catalase, caffeic acid O-methyltransferase, and pathogenesis-related protein 1 [PR1]) was analysed by quantitative real-time RT-PCR (qRT-PCR) which confirmed changed transcript levels upon ozone treatment of European beech saplings. The ESTs characterized will contribute to a better understanding of forest tree genomics and also to a comparison of ozone-responsive genes in woody and herbaceous plants.

Modelling of cluster emission from metal surfaces under ion impact

Using the molecular-dynamics technique, cluster emission for 5 keV Ar bombardment of a Cu (111) surface has been investigated using a many-body (tight binding) potential for the Cu-Cu interaction. The calculations allow us to analyse the basic processes underlying cluster emission. It is found that two distinct processes can be distinguished which lead to cluster emission under energetic ion bombardment. The first process causes the emission of small clusters, which are emitted by a collective motion during the development of the collision cascade within the first picosecond after impact. Thus, emission times of such clusters agree with the emission times of atoms in sputtering. Such a process can be envisioned if, for example, a few layers below the surface, an energetic recoil causes the development of a subcascade. Energy transferred by this event to the surface is strongly directional and can lead to the simultaneous emission of a group of neighbouring surface atoms, which in some cases will remain bounded and form a cluster after emission. Typically, clusters emitted by this mechanism consist of atoms, which are neighbouring in the target and are almost exclusively surface atoms, similar to all sputtered atoms. Emission of large clusters (cluster sizes of 10 or more atoms), as observed experimentally, is a puzzling phenomenon. From our calculations we conclude that the emission of such large clusters does not occur during the collisional phase of sputtering, but happens much later (5-10 ps after ion impact). Emission can occur for spike events, where all the energy of the impinging ion is deposited locally in a small volume near to the surface, and the sputtering yield is 3-5 times the average yield. Such events are rare, but we have found a few cases in our calculations where stable clusters consisting of more than 20 atoms were emitted. Melting of the spike volume occurs, and the high temperatures and pressures produced can cause emission of large fragments during the thermal phase. The composition of such large clusters is quite different from that of small clusters. They consist of atoms from different layers and the constituents are also generally not next-neighbour atoms. This change in origin of the cluster atoms reflects the mixing and diffusion processes occurring in the melted zone before emission. The calculations indicate that hydrodynamical phenomena might play a role in the emission of large fragments. Additional calculations, where the energy was distributed 'thermally' in a three-dimensional volume under the surface for 500 fs, give very similar results, even in such cases where the kinetic phase of the collision-cascade development was absent.

Interaction of liposome formulations with human skin in vitro

The interaction of liposome formulations consisting of Phospholipon 80 and sphingomyelin with human skin was investigated. These formulations were shown previously to have a composition-dependent effect on the penetration of Heparin into the skin. Fluorescence labelled phosphatidylethanolamine (PE-NBD) was incorporated in the liposomes and the depth in which the fluorescent phospholipid label enters into epidermal membrane and full thickness skin was studied by confocal laser scanning microscopy (CLSM). Confocal sections parallel to the surface of the skin were recorded in heat separated epidermis. An even distribution of phospholipid in the lipid matrix of the stratum corneum surrounding the corneocytes was observed with Phospholipon 80 but not when sphingomyelin was included in the formulation. The addition of Heparin which formed a coating around the liposomes, caused a strong localization of fluorescence within the epidermis. For full thickness skin, mechanical cross sections of skin were made and optical sections were recorded parallel to the plane of cut. Phospholipid penetrated and was distributed fairly homogeneously in the lower dermis layers within 30 min of application regardless of liposome composition and the presence of Heparin. This rather quick penetration process seemed to follow distinct pathways along the epidermis and the upper dermis, notably the hair follicle route. Thus, a strong and in some respects composition-dependent interaction of phospholipids with skin is evident. These observations, however, are limited to the level of phospholipid molecules, rather than of entire liposomes interacting with skin.

Heparin penetration into and permeation through human skin from aqueous and liposomal formulations in vitro

The transport of unfractionated (UH) and low molecular weight Heparin (LMWH) in human skin was investigated in vitro using heat separated epidermal membrane and dermis and the effect of liposomal formulations with Phospholipon(R) 80 (PL80) and Sphingomyelin (SM) was assessed. The distribution of Heparin within skin tissue was studied by the tape stripping method. Heparin concentrations were measured with a biological assay. Transepidermal water loss was determined to characterize barrier properties of skin. No consistent permeation of Heparin through epidermal membrane was detected. Penetration into the epidermal membrane was for LMWH significantly greater than for UH. Accumulation of UH was largely restricted to the outermost layers of the stratum corneum while LMWH penetrated into deeper epidermal layers. UH penetration into epidermis was detected for the PL80 liposomal formulation only. The extent of LMWH penetration was independent of the formulation, LMWH, however, showed a trend to accumulate in deeper epidermal layers for the PL80 compared to the aqueous formulation. Thus, molecular weight and liposomal formulations influenced the penetration pattern of Heparin in the epidermis. It can not be concluded whether the concentration of LMWH achieved at the blood capillaries is sufficient to exert a pharmacological effect. UH permeated readily through dermis irrespectively of formulation and its accumulation in the dermis was significantly enhanced and its lag time of permeation increased in the presence of SM liposomes.

Dynamics of laser desorption and ablation of metals at the threshold on the femtosecond time scale

The dynamics of the laser-ablation (-desorption) process of metals (Al, Ag, Fe, and Ni) initiated by 30 fs laser pulses has been investigated by interferometric time-resolved pump-probe measurements. It is postulated that a sufficiently high density of hot electrons is essential for achieving desorption of metal ions. In addition, we have observed a new and unexpected behavior characterized by delayed ablation for a pump-probe beam delay in the range of several ps for Al, Ni, and Fe. This second peak is attributed to the development of a liquid surface layer developing after a few ps. Molecular dynamics simulations support this assumption.

Not more than three tissue kallikreins identified from organs of the guinea pig

The large and varied multigene families of tissue kallikreins of rat and mouse are considered to selectively release as many bioactive peptides. In order to determine whether a similar family of enzymes is expressed in the organs of the guinea pig purification studies were performed. Tissue kallikreins from the submandibular gland, coagulating gland/prostate complex and the pancreas were separated by affinity chromatography on benzamidine-Sepharose. Amino-terminal sequences, the patterns of hydrolysis rates of a number of peptide p-nitroanilides, inactivation rates by active site-directed irreversible inhibitors, specific kininogenase activities and types of kinin released were used to probe the identity of the isolated enzymes. Guinea pig tissue kallikreins 1 and 2 have been reported previously. In the present study we have identified a third type, designated tissue kallikrein 1a because of its sequence similarity to kallikrein 1, which differs from the latter in the catalytic properties. The inferred occurrence of not more than two or three independent tissue kallikrein genes in the guinea pig contrasts with the varied family of enzymes expressed by the large number of such genes present in rats and mice. Expression in the guinea pig (and also in humans) of only a small number of tissue kallikreins makes specific processing of a multitude of biologically active peptides by such enzymes unlikely.

Chlamydia trachomatis antibody titers and hysterosalpingography in predicting tubal disease in infertility patients

OBJECTIVE

To determine if the number of diagnostic laparoscopies done on women without tubal adhesive disease could be reduced by testing for tubal disease with Chlamydia trachomatis antibody titers and hysterosalpingography (HSG), either singly or together.

DESIGN

Historical prospective chart review.

SETTING

The Colorado Kaiser Permanente Reproductive Endocrinology Clinic.

PATIENTS

All 703 infertility patients who had C. trachomatis antibody titers done from March 2, 1988 to April 30, 1992. The final study group was comprised of 218 patients who had antibody titers, HSG, and laparoscopy.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Sensitivity, negative predictive value, and false-positive rate were the test characteristics of interest. Tubal disease was identified by laparoscopy.

RESULTS

For HSG testing, the sensitivity was 78% and the negative predictive value was 85%. For C. trachomatis titers, the sensitivity was also 78% and the negative predictive value was 82%. Ninety-five percent confidence intervals for sensitivity and negative predictive value overlapped, indicating that there was no significant difference. However, false-negative rates were the same for the two tests, but false-positive rates were lowest for HSG and series testing.

CONCLUSIONS

To minimize false-positive tests and thus, to minimize unnecessary laparoscopies, HSG testing either alone or combined with the C. trachomatis antibody titer as series tests yielded a significantly lower false-positive rate. In our study group, if both tests were negative, tubal disease was identified on laparoscopy in only 5% of cases. Choice of most cost-effective test sequence will depend on who bears the cost. Further studies of cost-benefit using well-defined testing sequences are needed to determine if C. trachomatis antibody titers in series with HSG would be more cost effective than HSG alone in detecting tubal disease.

Altered luteinizing hormone pulse frequency in early follicular phase of the menstrual cycle with luteal phase defect patients in women

OBJECTIVE

To delineate the relationship between the pulsatile gonadotropin inputs in early follicular phase of the menstrual cycle and the P secretions by the corpus luteum in women.

DESIGN

For measuring pulsatile release of gonadotropin, blood samples were drawn every 15 minutes for 24 hours in the early follicular phase. Daily blood samples were drawn for LH, FSH, E2, and P.

SETTING

The reproductive endocrine unit of a university hospital.

PATIENTS

Fourteen patients with luteal phase defect (LPD) and 12 normally cycling women.

RESULTS

The length of follicular phase in LPD was significantly shorter than that of women with normal cycles. There were significant differences in LH pulsatile secretions and amplitudes in LPD patients when compared with those of women with normal cycles. Basal E2, PRL, and preovulatory E2 concentrations were not different between the two groups whereas the peak of P secretions in luteal phase was significantly decreased in LPD.

CONCLUSIONS

These data suggest that LPD may result from the altered LH pulse frequency in early follicular phase of the menstrual cycle. Whether this increased LH pulse frequency results from an intrinsic disease of the pulse oscillator or to some event in the preceding cycle remains unknown. It is tempting to speculate that an increased LH pulsatile secretion in the early follicular phase of menstrual cycles in patients with LPD may down-regulate the LH secretion at midcycle, thereby lowering the LH surge, which in turn reduces the P secretion in luteal phase.

Impact of histocompatibility antigens on pregnancy outcome

OBJECTIVE

The role of histocompatibility antigens in pregnancy outcome is controversial. This controversy may be because the initial studies were of small numbers or the patient groups were not homogeneous. The purpose of this study is to clarify these discrepant results by carrying out histocompatibility antigen typing and mixed lymphocyte culture on couples with idiopathic recurrent spontaneous abortion and by comparing results with those of fertile couples.

STUDY DESIGN

Sixty couples with at least three spontaneous abortions and 60 normal couples with at least two successful pregnancies were included. Histocompatibility antigen typing and mixed lymphocyte culture were performed by using the standard techniques. The data were analyzed statistically with the Fisher exact test and chi 2.

RESULTS

Our results failed to show any difference between normal and aborting couples with regard to HLA-A, HLA-B, and HLA-DR distribution or sharing or to mixed lymphocyte culture responsiveness.

CONCLUSION

Our study, along with other studies, emphasizes that the histocompatibility antigen system does not have an impact on pregnancy outcome.

Ovulation prediction and detection with the CUE Ovulation Predictor

Predicting ovulation is useful for managing the infertile patient and when done sufficiently in advance for fertility regulation by periodic abstinence. It has been reported that ovulation could be predicted by measurement of salivary and vaginal electrical resistance (SR and VR). These data from 32 menstrual cycles of 23 women were obtained to evaluate this technique. Data of 14 cycles were from subjects receiving clomiphene citrate (CC), while the others were from spontaneously ovulating subjects. A peak in SR was seen 5-7 days before the day of the LH peak in both natural and CC cycles. A correlation coefficient (r) of 0.94 was seen for the day of the SR peak and that of the LH peak. The SR trend was similar in both natural and CC cycles. VR in spontaneous cycles declined to a periovulatory nadir and then increased. The patterns of VR in CC cycles were similar except that values were initially depressed during and shortly after the end of CC therapy. Over 90% of VR increases were on the day of the LH peak and the day following. Results indicate that the method is useful for predicting ovulation in natural and CC cycles. Since the number of days by which ovulation is predicted exceeds the expected lifespan of spermatozoa in the female reproductive tract, the method also shows potential for use in natural family planning.

Physiological mechanisms associated with ovulation prediction using the CUE Ovulation Predictor

It has been shown that monitoring of salivary electrical resistance (SR) enables prediction of ovulation several days in advance, since a peak in SR is seen 5-6 days before the LH peak. This paper explores physiological mechanisms that may account for this change. The pathway whereby oestrogen stimulates aldosterone (ALDO) secretion acting through the renin-angiotensin system was considered. It is shown that this mechanism would only result in increasing SR as oestrogen values rise during the follicular phase and therefore is not an explanation of the SR peak and declining SR 5-6 days before the LH peak. The reported trend of sodium in milk of ovulating women parallels that of SR. It is shown that these changes are most likely to be due to a similar change in aldosterone levels. A possible role for adrenocorticotrophic hormone (ACTH) in causing the changes in aldosterone is discussed and supported with data from other independent studies as well as with preliminary data obtained from two normally ovulating subjects. Peaks in ACTH, ALDO and SR were coincidental and occurred 6 days before the LH peak. The temporal relationship observed among these variables suggest that ACTH, by affecting ALDO, modifies salivary electrolytes and hence SR.

Steroidogenesis in adrenal tumor cells: influence of cell shape

Y-1 adrenal tumor cells were grown on plastic, or plastic treated with poly(2-hydroxyethyl methacrylate) (polyHEMA) to produce concentration-dependent rounding (10(-5)-3 X 10(-4) M) of the cells or on plastic treated with poly-D-lysine (polylysine) to produce flat cells, in order to determine whether or not cell shape is correlated with steroid synthesis. The degree of rounding of cells was measured by determining mean cell height and longest cell diameter. Three measurements of steroid production were made: production of 20 alpha-dihydroprogesterone, transport of cholesterol to the inner mitochondrial membrane, and production of pregnenolone by isolated mitochondria. Cells grown on poly(HEMA) showed increase in mean cell height, decrease in longest diameter (i.e. rounding), and increase in all three measurements of steroidogenesis. In the case of synthesis of 20 alpha-dihydroprogesterone, the response was dependent on the concentration of poly(HEMA), being greater with higher concentrations (up to 10(-4) M), of this agent. Moreover the degree of rounding (cell height) was correlated with production of 20 alpha-dihydroprogesterone at three concentrations of poly(HEMA) (r = 0.93. ACTH at a supramaximal concentration produced increases in all of these responses to the poly(HEMA) surface. Polylysine produced flatter cells (lower mean height and greater longest diameter) than plastic and also inhibited all three steroidogenic responses to ACTH. (Bu)2cAMP exerted the same effects as ACTH. Growing cells on poly(HEMA) or polylysine did not affect production of cyclic AMP by the cells. Addition of poly(HEMA) or polylysine to the medium in which the cells were incubated, at the same concentrations as those used for influencing cell shape, was without effect on steroid synthesis or the response to ACTH. Cells grown on poly(HEMA) show decreased incorporation of [3H] thymidine into DNA. It is concluded that cell shape influences the delivery of cholesterol to inner mitochondrial membrane and in this way, increases the production of steroids by Y-1 cells and that the effects of poly(HEMA) on cell shape, cholesterol transport, and synthesis of DNA may involve microfilaments.

Prediction of ovulation with the use of oral and vaginal electrical measurements during treatment with clomiphene citrate

This study was undertaken to evaluate the usefulness of measuring salivary and vaginal electrical resistance in monitoring ovulation induced by clomiphene citrate (CC). Data from 28 cycles of 12 women treated with CC were compared with those of 18 cycles of 13 women who were ovulating spontaneously. Patterns of salivary readings in CC and spontaneous cycles were similar and showed a preovulatory peak 6.2 (mean) days before the luteinizing hormone peak. The trend in vaginal readings for CC cycles differed from that of spontaneous ovulations in that the values were depressed during and shortly after CC therapy. Occurrence of the periovulatory nadir and subsequent rise was common to both groups. The rise in vaginal readings CC cycles occurred within 24 hours of the luteinizing hormone peak in 88% of cases. Retrospective analysis showed that, based on this method, artificial insemination would have been timed appropriately in 25 of 27 cycles or in every cycle, depending on the protocol used. The results indicate that the method is equally useful for predicting and confirming ovulation in cycles in which CC was used to induce ovulation as it is in spontaneous cycles.

NADPH-cytochrome P-450 reductase from untreated rat testicular and liver microsomes: isolation and comparison

NADPH-cytochrome P-450 reductase (EC 1.6.2.4), the enzyme involved in progesterone 17-hydroxylation, was purified to apparent homogeneity by detergent solubilization of the microsomal fractions of liver and testis from untreated rats. The enzymes from these two tissues were then compared with regard to several parameters. The liver and testicular reductases have the same subunit mol wt (79,000), determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and have similar specific activity for cytochrome c reduction (48.1 and 58.2 mumol min-1 mg-1, respectively). The absolute flavin absorption spectra of liver and testicular reductase were very similar. The spectra of native, reduced, and oxidized reductases were characteristic of flavoprotein with two flavin groups. The Km values for NADPH during cytochrome reduction were shown to be the same, within experimental error (5.29 +/- 0.46 microM-1 for liver and 4.37 +/- 0.53 microM-1 for testis). Monospecific antiserum was prepared against both rat liver and testicular reductases. There were no antigenic differences demonstrated by immunological tests using either antibody preparation. Antiliver reductase antiserum was shown to inhibit testicular microsomal progesterone 17-hydroxylase activity by 70%. Testicular cytochrome c reductase activity was inhibited by 94%, and liver cytochrome c reductase activity was inhibited by 85%. Peptide maps of both forms of reductase isolated from immunoprecipitates showed very similar patterns after enzymatic proteolysis. These results indicate that microsomal NADPH-cytochrome P-450 reductase involved in steroid hydroxylations in untreated rat liver and testis could not be distinguished from each other by these methods and, therefore, are probably the same protein.

A new method for predicting and confirming ovulation

Evaluation of a method for predicting and confirming ovulation by measurement of vaginal and salivary electrical resistance (VER and SER) was the purpose of this study. Eighteen menstrual cycles from 13 subjects were analyzed. A clearly defined nadir in VER at day 0, the day of the luteinizing hormone (LH) peak, followed by a pronounced increase the following day was observed. A peak in SER was consistently observed 5 to 6 days before day 0. The correlation coefficient (r) between the cycle day of the SER peak and cycle day of the LH peak was 0.94. After the peak in SER, values were low for several days but increased 1 to 2 days before the LH peak. Results indicate that monitoring of SER and VER may provide the basis for a simple method for predicting and confirming ovulation.

Steroid interactions with cytochrome P-450 from testis microsomes

The cytochrome P-450 of gonadal microsomes is an integral component of the steroid converting enzymes, 17 alpha-hydroxylase and 17,20-lyase. Interaction of the steroid substrates with this cytochrome results in a shift in the Soret band as measured by difference spectroscopy. In these studies it is shown that in contrast to placental microsomal cytochrome P-450 which binds C19 steroids, testis microsomal cytochrome P-450 primarily binds C21 steroids. However, addition of a 17 alpha- methyl, 17 beta-acetate or a 17 beta-benzoate group to testosterone permits interaction. The addition of hydroxyl or methyl groups to other positions does not affect binding. The presence of multiple oxygen functions on C21 steroids, as in cortisol and corticosterone, precludes interaction. At least one oxygen function seems necessary for binding as 5 alpha- and 5 beta-pregnane do not bind whereas 20-deoxypregnenolone (5-pregnen-3 beta-ol) does bind. These findings indicate that factors in addition to hydrophobic interactions dictate the binding of steroid substrates to testis microsomal cytochrome P-450.

Role of actin in the responses of adrenal cells to ACTH and cyclic AMP: inhibition by DNase I

Erythrocyte ghosts were loaded with pancreatic DNase I and fused with Y-1 adrenal tumor cells to test the possibility that this enzyme might inhibit the steroidogenic responses of the cells to ACTH and cyclic AMP. Fusion of erythrocyte ghosts loaded with DNase I, but not those containing albumin, ovalbumin, boiled DNase I, or DNase I with excess G-actin, inhibited the increase in production of 20 alpha-dihydroprogesterone produced by ACTH and dibutyryl cyclic AMP; inhibition was concentration-dependent with 50% inhibition by 3 X 10(7) molecules of DNase I per cell. It was found that inhibition by DNase I was exerted at the step in the steroidogenic pathway at which cholesterol is transported to mitochondria where steroidogenesis begins. This was shown by measuring transport of cholesterol into the inner mitochondrial membrane, by measuring the production of pregnenolone by isolated mitochondria and by demonstrating that DNase I was without effect on the conversion of pregnenolone to 20 alpha-dihydroprogesterone (an end-product of steroid synthesis). The actin content of Y-1 cells was measured by two methods based upon inhibition of DNase I and by SDS gels following centrifugation. The cells were found to contain 2-3 X 10(7) molecules of actin per cell of which two-thirds is present as G-actin. Since DNase I is known to bind to G-actin to give a one to one complex, these and other findings suggest that at least some of the G-actin in the cells may be necessary for the steroidogenic responses to ACTH and cyclic AMP.

Isolated gonadotropin deficiency in three sisters

Three female siblings with isolated gonadotropin deficiency were studied. None demonstrated hyposmia or craniofacial abnormalities. Single doses of luteinizing hormone-releasing hormone and thyrotropin-releasing hormone (TRH) produced markedly different responses within the kindred. Following administration of TRH, one subject displayed a sharp rise in prolactin, but thyrotropin did not change.

Determination of steroid profiles in healthy and diseased states: identification and quantitation of a block of 17 alpha-hydroxylase

The steroid metabolic profile on a patient with a suspected block in steroid biosynthesis was analyzed by gas chromatography and gas chromatography-mass spectrometry. The results of this work led to an interpretation of a block at the 17 alpha-hydroxylase step. Although the steroid metabolic profile was complex, we could not detect any steroids with a hydroxy moiety at position C-17. The use of gas chromatography-mass spectrometry, in this case, was the method of choice for a final diagnosis because of the confusion that resulted from other, more classical, forms of analysis. Data from our patient's sample are reported and compared to normals and to other cases where a block in 17 alpha-hydroxylase have been reported.

Male pseudohermaphroditism due to 17 alpha-hydroxylase deficiency: diagnosis by gas chromatography--mass spectrometry

A case of male pseudohermaphroditism associated with 17 alpha-hydroxylase deficiency is reported in which the diagnosis was firmly established by gas chromatography-mass spectrometry. The patient was a 20-year-old genotypic male, phenotypic female who presented with primary amenorrhea, absence of body hair, and no breast development. She was hypertensive. Corticosterone and progesterone levels were very high and sex steroids were virtually absent. Gonadotropins were in the menopausal range. The results of radioimmunoassay were not diagnostic. Analysis of urine using gas chromatography-mass spectrometry revealed a striking absence of steroids with 17-oxygen function-nor were there any 18 or 19 carbon steroids. These results clearly establish a total deficiency of 17 alpha-hydroxylase activity.