Temperature Dependence of Anuran Distortion Product Otoacoustic Emissions

To study the possible involvement of energy-dependent mechanisms in the transduction of sound within the anuran ear, distortion product otoacoustic emissions (DPOAEs) were recorded in the northern leopard frog over a range of body temperatures. The effect of body temperature depended on the stimulus levels used and on the hearing organ under investigation. Low-level DPOAEs from the amphibian papilla (AP) were reversibly depressed for decreased body temperatures. Apparently, DPOAE generation in the AP depends on metabolic rate, indicating the involvement of active processes in the transduction of sound. In contrast, in the other hearing organ, the basilar papilla (BP), the effects of body temperature on DPOAEs were less pronounced, irrespective of the stimulus levels used. Apparently, metabolic rate is less influencing DPOAE generation. We interpret these results as evidence that no amplifier is involved in sound transduction in the BP. The passive functioning of the anuran BP would place this hearing organ in a unique position within tetrapod hearing, but may actually be beneficial to ectothermic species because it will provide the animal with a consistent spectral window, regardless of ambient or body temperature.     

Andrology: Intracytoplasmic injection of human spermatozoa into mouse oocytes: a useful model to investigate the oocyte-activating capacity and the karyotype of human spermatozoa

When intracytoplasmic sperm injection (ICSI) is performed, itis important to know the capacity of sperm cells to activatethe oocytes, although knowledge of their ability to fuse withthe oocytes is not vital. Hamster oocytes are not suitable forthis purpose because they are easily activated by the injectionprocedure itself. We therefore investigated whether mouse oocytescould be used to assess the activation properties of human spermatozoa.Mouse oocytes were randomized for injection with initially motilespermatozoa, medium, heat-treated or salt-extracted spermmatozoa,and the survival and activation rates were examined. About halfof the mouse oocytes survived the intracytoplasmic injectionof a human sperm cell. Unlike hamster oocytes, the rate of activationprovoked by the injection procedure itself was acceptably low(20%), resembling in this respect the behaviour of human oocytes.Following the injection of initially motile human spermatozoa,all mouse oocytes were activated. The injection of heat-treatedor salt-extracted human spermatozoa resulted in activation ratesof 14 and 15% respectively, comparable with the results followingsham ICSI. These data support the hypothesis of a sperm-associatedoocyte activation factor. In most activated oocytes, the humansperm nucleus decondensed to form a male pronucleus. Cytogeneticanalysis at the first metaphase revealed that human sperm chromosomeswere able to undergo replication in a heterologous environment.From our data we concluded that human spermatozoa can be injectedsuccessfully into mouse oocytes, resulting in a reasonable survivalrate, and that mouse oocytes provide a useful model for boththe assessment of the sperm-associated oocyte activation factorand the cytogenetic analysis of human spermatozoa.     

Physical-chemical studies on bovine eye lens proteins: I. Light-scattering and viscosity studies of low-molecular weight α-crystallin isolated from adult and embryonic bovine lenses

Low molecular weight α-crystallins, isolated from adult and embryonic bovine lenses, have been characterized using physical-chemical methods. From light-scattering measurements and from the Svedberg relation, a molecular weight of 785 000 ± 30 000 can be concluded. From hydrodynamic data, namely the sedimentation coefficient, the translational diffusion coefficient, the intrinsic viscosity and the rotational diffusion coefficient, a symmetric shape of the molecules in solution with a rather high hydration can be concluded. The low-molecular α-crystallins, isolated from the cortex of adult lenses and from embryonic lenses, have identical hydrodynamic parameters.     

Human chorionic gonadotrophin (hCG) in IUD users

The incidence of postimplantation pregnancy loss was assessed in 186 IUD users and 187 controls through use of a highly sensitive, specific radioimmunoassay for serum human chorionic gonadotropin (hCG). Previous studies have detected hCG in 10-19% of IUD users during the postovulatory phase of the menstrual cycle, indicating either that implantation had occurred or that the preimplantation blastocyst secretes detectable amounts of hCG. 3 of the 187 controls had detectable serum hCG and their serum luteinizing hormone (LH) concentrations exceeded 125 mIU/ml. In 3 of 186 IUD users, serum hCG was detected in the presence of normal or low serum LH concentrations. These findings suggest that the incidence of dectable hCG during the postovulatory phase is extremely low in IUD users and identical to that of postmenopausal and noncycling controls. It is concluded that embryonic implantation and subsequent early abortion are rare events in IUD users and that neither plays a role in the mode of action of the IUD.     

Identification and quantitative determination of nitrosoproline and nitrososarcosine and preliminary investigations on nitrosohydroxyproline in cured meat products.

A method for the quantitative determination of certain nonvolatile N-nitrosoamino acids has been developed. After a clean up procedure, using liquid-liquid extraction and ion exchange separation, the nitrosoamino acids are determined either by GC after conversion to their methylesters or by photolysis and subsequent determination of formed nitrite ion. Identification is made by GC-MS. Nitrosoproline and nitrososarcosine can be determined unambiguously; work on nitrosohydroxy-proline is in progress. Analysis of some cured meat products has shown that nitrosoproline may be present in relatively large amounts (340-440 mug/kg, confirmed by GC-MS) as compared to the amounts of volatile in notrosamines commonly found in these products. A trace of nitrososarcosine (about 10 mug/kg) was found in one product.     

Metoclopramide and breast milk

Thirteen primiparous nursing mothers participated in this placebo-controlled double blind trial of metoclopramide. Therapy was started on the first postpartum day and continued for 8 days. Seven women received metoclopramide (10 mg, 3 X dd). Serum prolactin and milk yield were measured during the trial. The breast milk composition was analysed during the trial and weekly for 3 wk after the trial. A detailed analysis of the amino acid content was performed on the 6th and 21st postpartum days. During the early puerperium the total milk yield was ca. 50% greater in the metoclopramide-treated group compared to the control group. The evolution of the breast milk composition was similar for both groups, except for the amino acid content. The shift in amino acid composition occurred earlier in the treatment group indicating that metoclopramide enhances the rate of transition from colostrum to mature milk.     

Hydatidiform mole combined with fetus: Extended diagnostic arsenal

Over 2,148 cycles of midcycle oral administration of R 2323 (50 mg. per day on Days 15, 16, and 17), the authors recorded a drug-failure pregnancy rate of 5 per cent and an unusually regular cycle length of 28 ± 2 days. During this trial, endometrial biopsies obtained in the luteal phase were examined by light and electron microscopy and compared to pretreatment biopsies. Light microscopy indicated a weakly secretory endometrium suggestive of some, albeit low, progesterone impregnation. Ultrastructural examination revealed deleterious changes in the development of the nucleolar channel system and giant mitochondria and a delay in the migration of glycogen granules. This low progesterone impregnation could be explained either by a direct effect of R 2323 on cell ultrastructure or by interference with progesterone availability. It would appear that R 2323 acts as a temporary substitute for progesterone at the receptor level but that it does not induce all the biological manifestations of this hormone, in particular, the endometrial changes required for implantation.