Comparison of plasmids of strains of Yersinia enterocolitica biovar 1A with the virulence plasmid of a pathogenic Y. enterocolitica strain

The plasmid content of apathogenic Y. enterocolitica biovar 1A strains was determined and the plasmids were compared with the virulence plasmid of a pathogenic Y. enterocolitica strain. About 38% of the selected biovar 1A strains contained plasmids of different sizes ranging from 2.7 kb to more than 70 kb. Some of the larger plasmids had a size similar to that of the virulence plasmid of a pathogenic reference strain. The restriction patterns of these plasmids were different from the restriction pattern of the virulence plasmid of the pathogenic reference strain. Differences were also observed in hybridization studies with the virulence plasmid. The plasmids from 15 out of 16 biovar 1A strains showed no homology, whereas the plasmid of one biovar 1A strain partially hybridized to the virulence plasmid.

The role of ultrasonography in the evaluation of endometrial receptivity following assisted reproductive treatments: a critical review

We set out to estimate the value of ultrasonographic parameters as prognostic indicators of implantation following in-vitro fertilization (IVF) and embryo transfer. Our survey included 414 natural cycles, 3558 cycles following ovarian stimulation for IVF and embryo transfer, and 411 cycles with hormone replacement therapy for oocyte donation, reviewing 27 reports identified in a computerized literature research. The ultrasonographic prognostic indicators for implantation evaluated included peri-ovulatory endometrial thickness and pattern and Doppler measurements of uterine artery blood flow. Topics include: definitions of the ultrasonographic parameters proposed to evaluate uterine receptivity; the clinical context in which they were used; the proposed optimal timing for sonographic evaluation; and, finally, their actual correlation with pregnancy rate following assisted reproductive technologies. For various sonographic parameters, negative predictive value, positive predictive value, sensitivity and specificity were calculated, based on published data. Sonographic parameters had a high negative predictive value and sensitivity, but a limited positive predictive value and low specificity. Several confounding factors may influence the interpretation of reports, and the statistical evaluation sometimes lacks calculation of the positive and negative predictive values of the parameters examined. Although ultrasonographic parameters of endometrial receptivity have a strong negative value in setting some minimum criteria, their value as prognostic indicators for implantation following embryo transfer has yet to be proved.

Plasma inflammatory cytokines correlate to the ovarian hyperstimulation syndrome

The objective of this study was to follow the kinetics of four inflammatory cytokines in the plasma and ascitic fluid of seven patients who developed severe ovarian hyperstimulation syndrome (OHSS) after induction of ovulation for in-vitro fertilization. Blood samples were obtained from these patients at three different times: upon hospitalization; when significant clinical improvement was evident; and after complete resolution. Samples were analysed for interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor alpha (TNF-alpha). Ascitic fluid was obtained by therapeutic paracentesis from all study patients during the active phase and analysed for these cytokines. Two control groups were available: the first included 15 women undergoing controlled ovarian stimulation for in-vitro fertilization without developing OHSS, while the second consisted of 25 healthy women not undergoing ovulation induction or any other medical treatment. High concentrations of IL-1, IL-6 and TNF-alpha were detected in all individuals upon admission for severe OHSS. Concentrations dropped significantly along with clinical improvement, reaching normal values after complete resolution. A statistically significant correlation was found between plasma cytokine concentrations and certain biological characteristics of the syndrome such as leukocytosis, increased haematocrit, and elevated plasma 17-beta-oestradiol concentrations. Ascitic fluid obtained from the study patients contained high IL-6 and IL-8 concentrations, while other cytokines were unaltered. These results suggest close association between inflammatory cytokines and the pathophysiology of the ovarian hyperstimulation syndrome.

Use of alfentanil for in vitro fertilization oocyte retrieval

STUDY OBJECTIVES

To determine alfentanil levels with a specific radioimmunoassay in serum and ovarian follicular fluid.

DESIGN

Observational study.

SETTING

University hospital.

PATIENTS

14 ASA status I women undergoing oocyte retrieval for in vitro fertilization.

INTERVENTIONS

General anesthesia was induced with alfentanil 15 micrograms/kg and midazolam 2 mg and maintained with alfentanil 0.5 mg, 60% nitrous oxide (N2O) in oxygen (O2) and midazolam up to a total of 4 mg. Oocyte retrieval was performed using a transvaginal ultrasound guided technique, 34 to 36 hours after human chorionic gonadotrophin administration.

MEASUREMENTS AND MAIN RESULTS

Mean procedure time for oocyte retrieval was 18 +/- 2.4 (SEM) minutes. All patients were fully awake within 5 minutes and all patients except one were able to move from the operating table to the stretcher with minimal help. Mean total protein concentration in the follicular fluid was 3.8 +/- 0.4 mg%. Maximal serum alfentanil concentrations (Cmax) were attained 5 minutes after start of the procedure (tmax) and were 92 +/- 20 ng/ml. In contrast, alfentanil concentrations in the follicular fluid increased constantly throughout the procedure up to 8.9 +/- 0.8 ng/ml at 15 minutes. Clinical pregnancy rate was 3 of 14 patients.

CONCLUSION

It is evident that during the oocyte retrieval procedure, the alfentanil concentrations in the follicular fluid are about ten-fold smaller than the serum alfentanil concentrations at the same time points. Similar pharmacokinetics have been shown when propofol was used as anesthetic. The low accumulation of alfentanil in the follicular fluid increases the attractiveness of alfentanil for anesthesia during oocyte retrieval for in vitro fertilization.

[Endometrial measurement by transvaginal sonography in postmenopausal bleeding]

We evaluated the role of transvaginal sonography (TVS) in the investigation of postmenopausal bleeding (PMB) in 50 women with PMB and 25 asymptomatic postmenopausal women presenting for periodic check-up, who served as controls. All those with PMB had a diagnostic curettage or hysterectomy within a week of TVS examination. Measurement of endometrial thickness was compared with the histopathological diagnosis of the endometrium. Of the 32 patients whose endometrial thickness was more than 5 mm, 22 had pathological changes in the endometrium. These included 6 cases of endometrial cancer and 16 with benign changes. All 18 patients of the PMB group with endometrial thickness less than 5 mm had normal endometrial histology. Endometrial thickness in all asymptomatic controls was less than 5 mm. Our results showed endometrial thickness greater than 5 mm to be 100% sensitive and 64% specific in identifying endometrial pathology. TVS follow-up without curettage may be considered for PMB patients with uniform endometrium less than 5 mm thick.

Ruptured tubo-ovarian abscess complicating transcervical cryopreserved embryo transfer

OBJECTIVE

To present a rare infectious complication related to transcervical ET, without prior transvaginal puncture.

DESIGN

Case report.

SETTING

Hadassah University Hospital, IVF-ET unit.

PATIENT

One patient undergoing cryopreserved-thawed ET.

INTERVENTIONS

Artificial preparation of the endometrium with E2 and P, followed by transcervical intrauterine cryopreserved-thawed embryo transfer.

RESULTS

After ET, severe pelvic inflammatory disease (PID) with ruptured tubo-ovarian abscess was diagnosed and treated.

CONCLUSIONS

Severe PID including tubo-ovarian abscess formation should be considered a potential complication after ET, even without transvaginal oocyte aspiration.

Delivery following intracytoplasmic injection of mature sperm cells recovered by testicular fine needle aspiration in a case of hypergonadotropic azoospermia due to maturation arrest

This is the first reported delivery following intracytoplasmic sperm injection (ICSI) of mature live testicular sperm cells collected in a case of hypergonadotrophic azoospermia with maturation arrest. The 30 year old couple presented with primary infertility of 11 years duration, the man being submitted in childhood to five orchidopexy operations for the treatment of cryptorchism. He had elevated serum follicle stimulating hormone (FSH; 18.8 IU/I), an atrophic left testis and a normal sized right testis, the biopsy of which diagnosed maturation arrest and focal scarring. The couple refused donor insemination for religious reasons and the only option was an attempt at testicular sperm collection. Multiple testicular and epididymal fine needle aspirations were performed, using an aspiration handle loaded with 20 ml syringe and 21-23 gauge butterfly needles. The mature spermatozoa recovered were used to inseminate the oocytes by ICSI. Prior to this procedure, the patient's wife underwent ovulation induction using a long protocol of mid-luteal gonadotrophin-releasing hormone analogue/human menopausal gonadotrophin (GnRHa/HMG). At oocyte retrieval, ten oocytes were recovered. Eight live sperm cells were recovered from the aspirates of the right testis. Following ICSI into four metaphase II and two metaphase I oocytes, one mature oocyte was fertilized, cleaved and was transferred to the uterus 48 h after oocyte retrieval. The patient conceived and delivered a 3300 g boy at term. In conclusion, our results demonstrate that this novel approach should be considered in cases with hypergonadotrophic azoospermia due to testicular failure. Further experience is needed to establish the exact criteria for its use.

Increased levels of redox-active iron in follicular fluid: a possible cause of free radical-mediated infertility in beta-thalassemia major

OBJECTIVE

Our purpose was to investigate the follicular fluid parameters associated with redox activity and the consequent production of the deleterious hydroxyl radical in beta-thalassemia major.

STUDY DESIGN

The levels of ferritin, total iron, total copper, and redox-active iron were measured in follicular fluid aspirated from three follicles during three consecutive ovum pickups from a patient with beta-thalassemia major and were compared with the levels in nine follicles aspirates from nine healthy control patients. The redox activity in the follicular fluid samples was monitored by the extent of follicular fluid-mediated deoxyribonucleic acid degradation and salicylate hydroxylation.

RESULTS

Total iron and ferritin concentrations were elevated in thalassemic follicular fluid samples compared with control samples (6.7 fold, and 53.3-fold, respectively), whereas the total copper concentration was similar. Thalassemic follicular fluid samples exhibited a marked increase of redox activity, indicating a higher potential of free radical production leading to deoxyribonucleic acid degradation. Likewise, free radical-induced conversion of salicylate to dihydroxybenzoic acid derivatives was enhanced in the thalassemic follicular fluid samples compared with controls (2,3-dihydroxybenzoic acid: 67.7 +/- 22 vs 20.3 +/- 12.9 ng/mg protein; 2,5-dihydroxybenzoic acid: 101.6 +/- 25.9 vs 4.42 +/- 2.7 ng/mg protein).

CONCLUSIONS

The increased level of redox activity found in the follicular fluid from a patient with beta-thalassemia major focuses the attention on the small fraction of redox-active iron ions as mediators of free radical production, inducing tissue injury and possibly contributing to impairment of reproduction in these patients.

Ovarian cysts in premenopausal and postmenopausal tamoxifen-treated women with breast cancer

OBJECTIVE

Our purpose was to investigate the frequency of ovarian cysts in tamoxifen-treated breast cancer patients.

STUDY DESIGN

The study population included 95 consecutive tamoxifen-treated premenopausal and postmenopausal women with breast cancer who were followed up by the outpatient clinic at the Hadassah University Hospital between September 1990 and June 1992. Tamoxifen was administered orally (20 mg/day). All patients underwent a pelvic examination and vaginal ultrasonography with a 5 MHz vaginal probe.

RESULTS

During the study 11 of 95 tamoxifen-treated breast cancer patients (11%) had ovarian cysts. Five cysts were detected in postmenopausal women (6.3% of the postmenopausal women) and six in premenopausal women (37.5% of the premenopausal women). In postmenopausal and premenopausal women the mean tamoxifen treatment interval was 19.4 +/- 7.8 months (range 4 to 48 months) and 28 +/- 6.1 months (range 12 to 54 months), respectively (p = 0.41). In 8 of the 11 patients the ovarian cystic enlargement disappeared after cessation of tamoxifen treatment. Two patients underwent laparotomy because of persistent cysts and the third because of a rapidly growing myoma. The three cysts were found to be benign.

CONCLUSION

Ovarian cysts are a common side effect of tamoxifen treatment. The ovarian cysts can develop in tamoxifen-treated premenopausal as well as postmenopausal women with breast cancer. Most of the tamoxifen-associated cysts disappear after tamoxifen treatment is abandoned.

The impact of endometrial preparation on implantation following cryopreserved-thawed-embryo transfer

The efficacy of three protocols of endometrial preparation (spontaneous cycles, A: artificial preparation, B; ovarian stimulation, C) for cryopreserved-thawed human embryo transfer (CT-ET). The implantation and clinical pregnancy rates per cycle in 236 women undergoing 381 consecutive CT-ETs were evaluated according to the endometrial preparation protocol. No statistically significant difference was found in implantation rates per embryo transfer (A = 5.6%, B = 5.6%, C = 4.6%) and clinical pregnancy rates per cycle (A = 16.9%, B = 16.5%, C = 15.6%) between the three endometrial preparation protocols used. In conclusion, the specific method of endometrial preparation for CT-ET had no significant impact upon the implantation rate.

[3H]1-aminocyclopropanecarboxylic acid, a novel probe for strychnine- insensitive glycine receptors

[3H]1-Aminocyclopropanecarboxylic acid (ACPC) exhibits high affinity, specific binding to strychnine-insensitive glycine receptors. In extensively washed rat forebrain membranes, the specific binding of [3H]ACPC was optimal at 25 degrees C in the presence of 10 mM MgCl2. Comparable levels of specific [3H]ACPC binding were obtained using centrifugation and filtration for separation of bound from free radioligand. [3H]ACPC labels two sites with Kdl and Bmax1 values of 129 +/- 34 nM and 2.30 +/- 0.37 pmol/mg protein and Kd2 and Bmax2 values of 7.26 +/- 1.69 microM and 20.6 +/- 2.2 pmol/mg protein for the high and low affinity sites, respectively. The Kd of [3H]ACPC (66 nM) estimated under non-equilibrium conditions (koff = 8.91 +/- 0.78 x 10(-3) s-1; kon = 1.35 x 10(-4) nM-1 s-1) was similar to the value obtained for the high affinity site obtained by equilibrium binding. The Kd1 of[3H]ACPC is in good agreement with the previously reported Ki values of ACPC to inhibit the binding of other glycinergic ligands including [3H]glycine, [3H]5,7-dichlorokynurenic acid (5,7-DCKA) and [3H]L-689,560 ((+/-)-4-(trans)-2-carboxy-5,7-dichloro-4- phenylaminocarbonylamino-1,2,3,4-tetrahydroquinoline). Moreover, the potencies of a series of glycine site ligands, including glycine. ACPC, 1-aminocyclobutanecarboxylic acid (ACBC), 5,7-DCKA, 7-chlorokynurenic acid (7-CKA), R(+)-3-amino-1-hydroxy-2- pyrrolidine (HA-966) and D-serine, to inhibit [3H]ACPC binding were highly correlated with their potencies to inhibit [3H]glycine and [3H]5,7-DCKA binding (r2 = 0.98-0.51). These results demonstrate that [3H]ACPC is a useful tool for examining the neurochemical and pharmacological properties of strychnine-insensitive glycine receptors.

Comparison between nafarelin acetate and D-Trp6-LHRH for temporary pituitary suppression in in vitro fertilization (IVF) patients: a prospective crossover study

PURPOSE

Nafarelin acetate is a new gonadotropin releasing (GnRH) agonist analogue with unique potency, intranasal administration, and convenient storage. Hence, nafarelin was considered as an alternative for temporary pituitary suppression in patients undergoing ovulation induction in IVF. A crossover treatment in a prospective study was performed including 40 women with bilateral obstructed tubes and normal ovarian function, treated in 80 ovulation induction cycles using the long protocol. Twenty patients used nafarelin acetate 600 micrograms/daily in their first cycle and received D-Trp6-LHRH, 0.5 mg/daily, in their following cycle. The other 20 women used decapeptyl in their cycle and received nafarelin in the second.

RESULTS

Estradiol suppression was achieved by both D-Trp6-LHRH and nafarelin at equal time intervals. The average total number of ampoules (P = 0.0005) and the length of administration of hMG required for ovarian stimulation (P = 0.0002) and the time interval between GnRHa initiation to oocyte retrieval (P = 0.04) was significantly lower in nafarelin cycles. The number and the distribution between large and small follicles as well as the average number of oocytes retrieved did not differ between the two GnRH analogues.

CONCLUSION

Our results demonstrate that nafarelin acetate is comparable to D-Trp6-LHRH for temporary pituitary suppression used for controlled ovarian stimulation in IVF patients. However, using nafarelin ovarian stimulation was achieved with few ampoules of hMG, administered for a shorter period of time, thus with a lesser cost.

Local control of granule cell generation by cerebellar Purkinje cells

Cerebellar Purkinje cells were ablated by the specific expression of diphtheria toxin in these cells in transgenic mice. Purkinje cell degeneration during early postnatal development shows a zonally restricted pattern which has been exploited in order to look for local secondary effects. The most obvious early effect is the alignment of gaps in the Purkinje cell layer with dramatically thinned zones in the overlying EGL, the germinal layer from which granule cells are generated. Within these EGL zones in the transgenic mutant, markers that distinguish matrix from mantle cells demonstrate a preferential loss of the proliferative cells. Comparison of BrdU incorporation in the mutant vs wild-type confirms the reduction in proliferation. In the mutant, in situ labeling of DNA fragmentation associated with apoptotic cell death shows abundant labeling of granule cells that have exited the EGL, but not of progenitor cells in the EGL. Thus, although a trophic role for Purkinje cells has been well documented, these observations further suggest a mitogenic role which can be exerted locally.

Constrained and unconstrained postures of the mandible--a break with tradition?

Evaluation of detailed electrognathographic recordings of various movements of the mandible (and points on it) suggested interpretations at variance with some traditional concepts. Data previously accumulated from several sources were subjected to critical analysis. An objective was to assess the manner in which two rotations of the mandible influenced its postures during trials of mastication and deliberate lateral excursions. Rotations about a vertical and an antero-posterior axis appear to facilitate a greater functional posturing potential of the mandible than has previously been reported. In most instances the influence of the rotations upon mandibular posture is considerably greater than the size of the recorded angles would suggest. Some of the resulting postures seem to challenge concepts derived strictly from cadaverine anatomy. For example, during mastication the condyle does not simply glide forward and backward relative to the eminence but may be distracted downward away from it for a part of the time. Furthermore, the ability of a subject to effect a considerable variety of mandibular postures challenges traditional reliance upon constrained mandibular movements as a means of evaluating function.

Embryo growth rate in vitro as an indicator of embryo quality in IVF cycles

PURPOSE

The role of embryo growth rate in vitro as an isolated indicator of embryo quality in IVF was evaluated retrospectively.

METHODS

Comparison was made between 98 cycles (group 1), in which only embryos at a cleavage stage of two to three blastomers were transferred, and 99 cycles (group 2), in which all embryos were transferred at a cleavage stage of four or more blastomers. Embryos were transferred at a fixed interval of 42 to 44 h following oocyte insemination. The mean patients' age, number of oocytes recovered and number of embryos transferred per cycle were similar in both groups.

RESULTS

The pregnancy rate and the take-home-baby rate were significantly higher in group 2 as compared to group 1 (22.2% vs 7.1% and 16.2% vs 4.1%; P < 0.05 and P < 0.001, respectively).

CONCLUSIONS

These results demonstrate that embryos with a slow cleavage rate in vitro are less likely to produce pregnancy following IVF-ET and that the cleavage stage is a valuable criteria in the selection of the best embryo for transfer.

A comparison between a standard and reduced dose of D-Trp-6-luteinizing hormone-releasing hormone administered after pituitary suppression for in-vitro fertilization

A randomized prospective study was undertaken to compare low and standard luteinizing hormone-releasing hormone agonist (LHRHa) dosage used in combination with gonadotrophins in ovarian stimulation for in-vitro fertilization (IVF). A total of 42 ovulatory patients with mechanical infertility were administered 0.5 mg/day LHRHa (Decapeptyl) from day 21 of their cycles for 14 days. Following down-regulation, patients were randomly allocated to continue with the same dose of LHRHa (22 patients, group A) or to receive a lower dose of 0.1 mg/day LHRHa (20 patients, group B) during folliculogenesis. Luteal phase was supported by daily i.m. progesterone (50 mg) injections and human chorionic gonadotrophin (HCG; 1500 IU) every 4 days. Ovarian response, human menopausal gonadotrophin (HMG) dosage used for induction of ovulation, evidence of premature luteinization, and clinical and laboratory IVF outcome, were compared between groups A and B. The two groups were comparable in respect of: age (32.6 +/- 0.7 and 33.0 +/- 0.9 years), HMG dosage (33.0 +/- 1.6 and 36.0 +/- 2.5 ampoules), day of HCG (11.2 +/- 0.3 and 12.2 +/- 0.4), oocytes/patient (13.3 +/- 1.0 and 12.9 +/- 1.3), fertilization rate (68.5 and 65.2%), cleavage rate (95% for both), pregnancy/embryo transfer (32 and 35%) and implantation rate (10.8 and 10.5%), for groups A and B respectively. There was no evidence of premature luteinization or luteolysis in either group. It was concluded that lowering the dose of LHRHa to 0.1 mg/day during folliculogenesis had no adverse effect on ovarian response or clinical results. However, it had no advantage in reducing the HMG dose used for ovulation induction.

Sonographic evaluation of fetal head extension and maternal pelvis in cases of breech presentation

BACKGROUND

To investigate whether sonographic examination of the fetal head extension, pelvic adequacy and fetal position, could replace the traditional x-ray method in the evaluation of the breech in labor.

METHODS

Seventy-two parturients admitted in labor with a breech presentation were prospectively evaluated by a newly proposed ultrasonographic approach. The head extension, obstetric conjugate and fetal attitude obtained were further compared to the gold standard radiologic measurements.

RESULTS

A highly significant correlation between ultrasonic and x-ray measurements for the fetal head extension (r = 0.8696; p < 0.0001), obstetric conjugate (r = 0.8931; p < 0.0001), as well as high reliability (95.5%) in diagnosing the breech variant by ultrasound have been found.

CONCLUSIONS

Ultrasonic evaluation of breech presentation, as performed by the proposed method, is simple, easy to perform and compares well with the standard radiologic studies. It is suggested that modern ultrasonic technique, which carries no risk of ionizing radiation, may replace traditional x-ray examination of the breech in labor.

The use of vaginal tablets as a vehicle for steroid replacement in a donor oocyte program

Nine women enrolled in the donor egg program received in a preparatory cycle 6 mg of E2 by vaginal tablets two times per day for the first 14 days, followed by a combined preparation of 6 mg of E2 and 50 mg of P as vaginal tablets, two times per day for another 14 days. Adequate serum levels of E2 and P and favorable sonographic endometrial thickness were achieved throughout the cycle in all patients. Eight endometrial biopsies taken on days 25 to 26 were independently assessed as being representative of day 25 +/- 2. One endometrial biopsy was out of phase. It is concluded that vaginal tablets of E2, followed by a combined preparation of vaginal tablets of E2 and P, is an effective method for establishing an appropriately developed endometrium in a donor oocyte program. Endometrial preparation in donor oocyte programs can be simplified by the use of these tablets.

The role of estrogen support during the luteal phase of in vitro fertilization-embryo transplant cycles: a comparative study between progesterone alone and estrogen and progesterone support

OBJECTIVE

To evaluate the possible role for estrogen supplementation to the P luteal phase support of GnRH agonists (GnRH-a)- and hMG-induced IVF-ET cycles.

SETTING

In vitro fertilization unit in a tertiary care university hospital.

DESIGN

A prospectively randomized study.

PATIENTS

One hundred consecutive patients undergoing ET after IVF were assigned into one of two luteal supplementation regimens.

INTERVENTIONS

In all patients enrolled in the study, ovulation was induced using the midluteal regimen for pituitary down regulation with GnRH-a followed by follicular stimulation with hMG. The first group received IM P 50 mg/d, as luteal phase support, starting the day of ET. The second group received the same dosage of P, combined with oral E2 valerate, 2 mg/d. Serum levels of P and E2 were monitored every 4 days for 16 days after ET.

MAIN OUTCOME MEASURES

Pregnancy rates (PRs) and live birth rates per ET.

RESULTS

No significant difference in E2 or P levels throughout the cycle was observed between groups. Similar PRs per ET and the live birth rates were also observed between group A and B (28% versus 26.5% and 78.6% versus 76.1%, respectively).

CONCLUSION

No advantage was found in the addition of E2 valerate to P luteal phase support of GnRH-a- and hMG-induced IVF-ET cycles.

Splicing defective mutants of the COXI gene of yeast mitochondrial DNA: initial definition of the maturase domain of the group II intron aI2

Six mutations blocking the function of a seven intron form of the mitochondrial gene encoding subunit I of cytochrome c oxidase (COXI) and mapping upstream of exon 3 were isolated and characterized. A cis-dominant mutant of the group IIA intron 1 defines a helical portion of the C1 substructure of domain 1 as essential for splicing. A trans-recessive mutant confirms that the intron 1 reading frame encodes a maturase function. A cis-dominant mutant in exon 2 was found to have no effect on the splicing of intron 1 or 2. A trans-recessive mutant, located in the group IIA intron 2, demonstrates for the first time that intron 2 encodes a maturase. A genetic dissection of the five missense mutations present in the intron 2 reading frame of that strain demonstrates that the maturase defect results from one or both of the missense mutations in a newly-recognized conserved sequence called domain X.

Defective oocytes as a possible cause of infertility in a beta-thalassaemia major patient

Impaired reproduction is common among patients afflicted with beta-thalassaemia major and is attributed mainly to the deposition of haemosiderin in the pituitary gland and ovaries. In-vitro fertilization (IVF)--embryo transfer cycles including ovum donation cycles are described for the first time in a patient with beta-thalassaemia major. The patient's oocytes were not fertilized by the husband's sperm in repeated IVF attempts. However, when donated oocytes were used, in two consecutive cycles, most were fertilized by the husband, yielding pregnancies after each embryo transfer. It is suggested that in this case of beta-thalassaemia major, impaired oocyte function contributed to infertility. However, a possible association between thalassaemia major and defective oocytes should be tested on a basis of additional IVF-embryo transfer cycles in these patients.

The determination of optimal human jaw movements based on their association with chewing performance

Chewing performance is an expression of the functional capacity of the jaws and teeth. In a recent study of fully dentate subjects, the variation in chewing performance could not be explained by differences in occlusal contact area. It was now decided to investigate the possibility that chewing performance might be associated with certain patterns of jaw movement. Data from two previous studies using the same subjects were analysed using a step-wise regression to select variables of jaw movement that could predict chewing performance. A multivariate model with an R2 value of 0.79 (p < 0.000) was generated with particle size as the dependent variable. Eight components of jaw movement made up the independent variables. Some of the more dominant variables in the model were those that describe a wide, bilateral chewing cycle with a predominantly lateral path of closure. Another powerful predictor of efficient chewing was a smooth, flowing movement with minimal changes in velocity. The inclusion of occlusal contact area in the model did not enhance its predictive capability. It was concluded that selected jaw-movement variables were significant determinations of chewing performance, and therefore could contribute to developing a baseline for normal masticatory function.

Severe sensory and sympathetic neuropathies in mice carrying a disrupted Trk/NGF receptor gene

Nerve growth factor (NGF) induces neurite outgrowth and promotes survival of embryonic sensory and sympathetic neurons in culture. In vivo, NGF decreases the extent of naturally occurring cell death in developing sympathetic ganglia and protects cholinergic neurons of the basal forebrain and caudatoputamen. NGF interacts with the low-affinity p75 receptor and with Trk, a receptor tyrosine kinase encoded by the trk proto-oncogene. To study the role of Trk in vivo, we have ablated the gene in embryonic stem cells by homologous recombination. Mice lacking Trk have severe sensory and sympathetic neuropathies and most die within one month of birth. They have extensive neuronal cell loss in trigeminal, sympathetic and dorsal root ganglia, as well as a decrease in the cholinergic basal forebrain projections to the hippocampus and cortex. These findings demonstrate that Trk is the primary mediator of the trophic actions of NGF in vivo and that this signalling pathway plays a crucial role in the development of both the peripheral and the central nervous systems.

A comparison of sonographic growth curves of triplet and twin fetuses

Sonographic growth curves of 47 normal triplet pregnancies were compared with those of 71 uncomplicated twin gestations. Starting from the 25th week, the biparietal diameter in triplets was found to lag progressively compared with that of twins, reaching a mean difference of 2 weeks at 36 weeks gestation. Similarly, a significant difference was found between the femur length and head to abdomen circumference ratio growth curves of triplets and twins. It is concluded that as pregnancy continues from the 25th to the 36th gestational week, there is a significant delay in the growth patterns of normal triplet pregnancies compared with twin gestations.