Evaluating factors associated with paediatric cochlear implant outcome in four cochlear implant satellite centres in Malaysia

INTRODUCTION

Many factors are associated with cochlear implant (CI) outcomes and various methods of assessment for auditory and speech performance outcomes in CI are available globally. The objective of this study is to identify factors relating to CI outcomes in paediatric population that suits local context.

MATERIALS AND METHODS

A total of 18 factors consisted of variables which emphasise on audiological, CI service team, speech therapy, and family-related factors. These factors were then retrospectively analyzed among CI recipients. The outcome measurements of categorical auditory performance II (CAP-II) and speech intelligibility rating (SIR) were used to individually study each factor. Kruskal-Wallis H Test and Fisher Exact Test used with p-value <0.05 were considered significant.

RESULTS

There were significant associations between post- CI CAP-II with type of hearing loss, hearing aid usage per day and mode of communication, attention, attending audiology and speech session, and siblings. For post-CI SIR, hearing aid usage per day, attention, mode of communication, attending audiology and speech session, initiatives, and siblings were statistically significant.

CONCLUSION

The factors affecting the outcome of CI are dynamic. Some of the factors have demonstrated to be associated with the auditory and speech outcome in CI recipients while some factors failed to replicate similar findings. Further prospective research may refine the outcome of individual factors.

Development of a mental script for the mental practice of micro suturing: a methodological approach

INTRODUCTION

Motor imagery and mental practice are important for the acquisition and mastery of surgical skills. The success of this technique relies on the use of a well-developed mental script. In this study, we shared how we developed a mental script for basic micro suturing training by using a low-fidelity rubber glove model.

METHODS

This study applied the design and development research framework. Five expert surgeons developed a mental script by performing a cognitive walkthrough to repair a vertical opening in a rubber glove model, followed by hierarchical task analysis. A draft script was created, and its face and content validity assessed with a checking-back process. Twenty-eight surgeons used the Mental Imagery Questionnaire (MIQ) to assess the validity of the final script.

RESULTS

The process of developing the mental script is detailed. The assessment by the expert panel showed the mental script had good face and content validity. The mean overall MIQ score was 5.2±1.1 (standard deviation), demonstrating the validity of generating mental imagery from the mental script developed in this study for micro suturing in the rubber glove model.

CONCLUSION

The methodological approach described in this study is based on a design and development research framework to teach surgical skills. This model is inexpensive and easily accessible, addressing the challenges of reduced opportunities to practise surgical skills. However, although motor skills are important, the surgeon's other non-technical expertise is not addressed with this model. Thus, this model should act as one surgical training approach, but not replace it.

Integrating instructional design principles into surgical skills training models: an innovative approach

OBJECTIVE

Surgical training programmes are evolving from time-based to competency-based schedules, which define expected learning outcomes in surgical knowledge, clinical and technical skills according to training levels. This article aims to review current models in surgical skills acquisition and to propose an integrative process-driven, outcomes-based model for surgical skills acquisition and mastery.

DESIGN

A literature review was conducted on the theories of motor skills acquisition using PubMed, Web of Science and Google Scholar from 2010 to February 2020. The review was limited to theories and models on surgical skills acquisition and mastery. Four models of surgical skills acquisition were included: Fitts and Posner's three-stage model of motor skills acquisition, Bandura's social learning theory, Ericsson's deliberate practice model and Jeannerod's motor simulation theory. These models are deficient in that there is no universally accessible opportunity to practise the surgical procedure outside of the operating theatre and without access to physical simulators.

RESULTS

We propose an innovative model that allows deliberate practice of the procedure without the need for expensive physical simulators, and provides an on-demand, self-directed practice by the trainees to achieve the level of mastery. This new model, which incorporates motor imagery and mental practice, augmented by deliberate practice, will provide an alternative training path for expert performance in surgical procedures.

CONCLUSIONS

The innovative model provides a solution to the reduced opportunity for practice by surgical trainees to achieve mastery in surgical motor skills.

Combination of hysteroscopic resection of endomyometrium with insertion of Mirena: An alternative treatment for adenomyosis

Adenomyosis is a common gynaecological condition encountered in clinical practice. Treatment of adenomyosis can present a great challenge to gynaecologists as women often become resistant to hormonal treatment eventually needing surgical intervention. Hysterectomy has long been the definitive treatment for adenomyosis. However, with women currently being diagnosed at an earlier age and still have not completed their family, there is an increasing demand for effective intervention with uterine conservation. We report here two cases of patients who had undergone a combination of hysteroscopic resection of the endomyometrium combined with Mirena insertion with successful outcome.

Imported Falciparum Malaria: A case series in a tertiary hospital

INTRODUCTION

Malaysia declared its intent to eliminate malaria by 2020, with a phased goal of achieving zero local transmission. Nonetheless, Malaysia is highl susceptible to malaria importation due to geographical proximity to high-burden countries e.g. Thailand, Myanmar and high influx of foreign workers and students from Asia and Africa.

CASE SERIES

We accumulated all malaria cases diagnosed in a tertiary hospital within a period of two years. Three cases were reported, where all of the patients were foreigners with recent travel history to African countries. All of them were infected by P. falciparum, responded to treatment and discharged well.

DISCUSSION

This case series highlighted the importance of acquiring recent travel history during history taking and having a high index of suspicions on malaria when dealing with feverish patients originated particularly from African countries.

Nanoparticles carrying fingolimod and methotrexate enables targeted induction of apoptosis and immobilization of invasive thyroid cancer

Metastatic tumors are the main cause of cancer-related death, as the invading cancer cells disrupt normal functions of distant organs and are nearly impossible to eradicate by traditional cancer therapeutics. This is of special concern when the cancer has created multiple metastases and extensive surgery would be too dangerous to execute. Therefore, combination chemotherapy is often the selected treatment form. However, drug cocktails often have severe adverse effects on healthy cells, whereby the development of targeted drug delivery could minimize side-effects of drugs and increase the efficacy of the combination therapy. In this study, we utilized the folate antagonist methotrexate (MTX) as targeting ligand conjugated onto mesoporous silica nanoparticles (MSNs) for selective eradication of folate receptor-expressing invasive thyroid cancer cells. The MSNs was subsequently loaded with the drug fingolimod (FTY720), which has previously been shown to efficiently inhibit proliferation and invasion of aggressive thyroid cancer cells. To assess the efficiency of our carrier system, comprehensive in vitro methods were employed; including flow cytometry, confocal microscopy, viability assays, invasion assay, and label-free imaging techniques. The in vitro results show that MTX-conjugated and FTY720-loaded MSNs potently attenuated both the proliferation and invasion of the cancerous thyroid cells while keeping the off-target effects in normal thyroid cells reasonably low. For a more physiologically relevant in vivo approach we utilized the chick chorioallantoic membrane (CAM) assay, showing decreased invasive behavior of the thyroid derived xenografts and an increased necrotic phenotype compared to tumors that received the free drug cocktail. Thus, the developed multidrug-loaded MSNs effectively induced apoptosis and immobilization of invasive thyroid cancer cells, and could potentially be used as a carrier system for targeted drug delivery for the treatment of diverse forms of aggressive cancers that expresses folate receptors.

Carbapenem-Resistant Enterobactericeae: ClinicoEpidemiological Perspective

Since its first discovery in 1996, Carbapenem-resistant Enterobactericeae (CRE) has been increasingly reported as a cause of infections particularly in immunocompromised patients. With limited treatment options, these multidrug-resistant organisms are associated with high mortality rates and are now recognized as an important cause of health-care associated infections. This study aimed to determine the prevalence of CRE at a 500-bedded tertiary hospital in Selangor, Malaysia. This study identified and analyzed CRE culture results from January 2015 to December 2016. The isolates were identified by conventional and Vitek 2® methods. Susceptibility tests were done by disk diffusion technique and confirmed by E-test. Polymerase chain reaction was performed to identify NDM-1, KPC, OXA-48, VIM and IMP genes. Demographic data and clinical characteristics were collected from the Hospital Information System. The prevalence of CRE in 2015 and 2016 was 0.3% (5/1590) and 1.2% (17/1402) respectively. 65% of the patients had underlying haematological disorders. Majority (81.8%) of the isolates were Klebsiella pneumoniae, followed by Serratia marcescens, Escherichia coli, and Citrobacter koseri. Klebsiella pneumoniae that co-produced NDM-1 and OXA48 genes were the most common encounter (41%), followed by OXA-48 (35%), NDM-1 (12%) and KPC (6%). All isolates were resistant to all generations of cephalosporin and carbapenem. The rate of resistance to tigecycline, polymyxin B and colistin were quite high; 46% (5 from 12 isolates), 17% (2/12) and 17% (3/17) respectively. The prevalence of CRE in this institution was relatively low. However, there is a high prevalence of OXA-48 and NDM co-producer amongst CRE isolates. Physicians should have high index of CRE suspicion in hematological patients.

Study on the physical and chemical composition of agro wastes for the production of 5-hydroxymethylfurfural

Treated sludge, goat manure, sugarcane bagasse, empty fruit bunches of oil palm (EFBP) and dry leaves are agro wastes that have high potential for use as feedstocks for the production of 5-hydroxymethylfurfural (5-HMF). The focus of this study is to investigate the production of 5-HMF from agro wastes via co-hydrothermal (CHT) treatment and extraction. Present study include examine on agro waste's physical and chemical properties and also their thermal degradation behaviour. The analysis of the bio-oil products is conducted by FTIR and GC-MS. Co-hydrothermal experiments were conducted at a temperature of 300°C with an experimental time of 15min, followed by alcohol extraction. Highest carbon and hydrogen content are 45.94% and 6.49% (dry leaves) with maximum high heating value 18.39MJ/kg (dry leaves) and fix carbon value 6.60 (goat manure). Through CHT about 39% 5-HMF, 22.97% carboxylic acids, 0.97% of aromatic and 0.73% aldehyde obtained.

The synthetic molecules YK51 and YK73 attenuate replication of dengue virus serotype 2

Dengue virus infection has been posing alarming economic and social burden on affected nations. It is estimated that 50-100 million dengue infections occur annually with over 2.5 billion people at risk for endemic transmission. In the effort to develop effective antiviral agents, we previously reported potential antiviral activities from selected array of natural products and compounds against dengue virus serotype 2 (DV2). In this study, we report the synthesis of two efficacious novel compounds, YK51 and YK73, and their activities against DV2 replication. Both compounds were chemically synthesised from nicotinic acid using a modified method for the synthesis of dihydropyridine. The products were tested with cell-based assays against DV2 followed by a serine protease assay. As a result, both YK51 and YK73 exhibited intriguing antiviral properties with EC₅₀ of 3.2 and 2.4 µM, respectively. In addition, YK51 and YK73 were found to attenuate the synthesis of intracellular viral RNA and protect the switching of non-classic mechanism of protein translation. These compounds demonstrated inhibitory properties toward the activity of DV2 serine protease in a dose dependent manner. These findings demonstrate that both YK51 and YK73 serve as DV2 serine protease inhibitors that abrogate viral RNA synthesis and translation. Further investigation on these compounds to corroborate its therapeutic properties towards dengue is warranted.

Decidualization of the canine uterus: From early until late gestational in vivo morphological observations, and functional characterization of immortalized canine uterine stromal cell lines

The apparent lack of classical mechanisms for maternal recognition of pregnancy is one of the most intriguing features of canine reproduction. Consequently, similar levels of circulating luteal steroids are observed in pregnant and non-pregnant dogs. However, the early pre-implantation canine embryo locally modulates uterine responses to its presence, facilitating the successful onset of pregnancy. As a part of this interaction, the canine uterus undergoes a species-specific decidualization. Maternal stroma-derived decidual cells develop, the only cells of the canine placenta expressing progesterone receptor (PGR). There exists an acute need for an in vitro stable cell line model for canine decidualization. Therefore, herein our goal was to establish, immortalize and characterize such a cell line. We immortalized three monolayer dog uterine stromal (DUS) cell lines by stably transfecting them with SV40Tag oncogene. Cells retained their mesenchymal character for over 30 passages, as evidenced by VIMENTIN staining. Genomic incorporation of the SV40Tag protein was confirmed by immunofluorescence and Western blot analyses. Cells submitted to a classical in vitro decidualization protocol (N6,2'-O-dibutyryladenosine-3',5'-cyclic monophosphate) revealed upregulated gene levels of selected major decidualization markers (e.g. PRLR, PGR, IGF1, PTGES). Additionally, the basic decidualization capability of PGE2 was demonstrated, revealing increased levels of, for example, PGR and PRLR gene expression, thereby implying its involvement in the progesterone-dependent decidualization in the canine uterus. In summary, our in vitro model with immortalized DUS cell line could serve as an ideal and unique model to study the underlying molecular and endocrine mechanisms of canine decidualization.

Room temperature ammonia sensing using tapered multimode fiber coated with polyaniline nanofibers

We demonstrate an ammonia sensor composed of a tapered multimode fiber coated with polyaniline nanofibers that operates at room temperature (26°C). The optical properties of the polyaniline layer changes when it is exposed to ammonia, leading to a change in the absorption of evanescent field. The fiber sensor was tested by exposing it to ammonia at different concentrations and the absorbance is measured using a spectrophotometer system. Measured response and recovery times are about 2.27 minutes and 9.73 minutes, respectively. The sensor sensitivity can be controlled by adjusting the tapered fiber diameter and the highest sensitivity is achieved when the diameter is reduced to 20 µm.

Choroidal osteoma - case reports

Choroidal osteoma is a rare disease. In this article four case histories were described. All were female and young patient. One patient had bilateral and other three had unilateral involvement. They had no family history. One patient reported at eye department in Bangabandhu Sheikh Mujib Medical University (BSMMU) and the other three patients reported in Bangladesh Eye Hospital. Choroidal osteoma is a benign tumor. It is diagnosed by fundoscopy, ocular B-scan ultrasonography, x-ray orbit, FFA, OCT and CT-scan of orbit. Most patients do not require treatment. Hemorrhage on the lesion suggests the presence of sub-retinal neovascularization which are typically treated with laser or intra-vitreal anti-VEGF.

Screening of antiviral activities in medicinal plants extracts against dengue virus using dengue NS2B-NS3 protease assay

Dengue virus infects millions of people worldwide and there is no vaccine or anti-dengue therapeutic available. Screening large numbers of medicinal plants for anti-dengue activities is an alternative strategy in order to find the potent therapeutic compounds. Therefore, this study was designed to identify anti-dengue activities in nineteen medicinal plant extracts that are used in traditional medicine. Local medicinal plants Vernonia cinerea, Hemigraphis reptans, Hedyotis auricularia, Laurentia longiflora, Tridax procumbers and Senna angustifolia were used in this study. The highest inhibitory activates against dengue NS2B-NS3pro was observed in ethanolic extract of S. angustifolia leaves, methanolic extract of V. cinerea leaves and ethanol extract of T. procumbens stems. These findings were further verified by in vitro viral inhibition assay. Methanolic extract of V. cinerea leaves, ethanol extract of T. procumbens stems and at less extent ethanolic extract of S. angustifolia leaves were able to maintain the normal morphology of DENV2-infected Vero cells without causing much cytopathic effects (CPE). The percentage of viral inhibition of V. cinerea and T. procumbens extracts were significantly higher than S. angustifolia extract as measured by plaque formation assay and RT-qPCR. In conclusion, The outcome of this study showed that the methanolic extract of V. cinerea leaves and ethanol extract of T. procumbens stems possessed high inhibitory activates against dengue virus that worth more investigation.

Ototoxicity screening of patients treated with streptomycin using distortion product otoacoustic emissions

OBJECTIVE

Pure tone audiometry (PTA) is currently widely used to monitor ototoxicity, but this method is time-consuming. Here we validate distortion product otoacoustic emission (DPOAE) as an instrument for early detection of ototoxicity.

METHODS

A cohort study was performed on newly diagnosed tuberculosis patients who were treated with streptomycin. The patients underwent hearing assessment using conventional PTA and high-frequency DPOAE (8, 9 and 10 kHz) on days 0, 7, 14, 28 and 56 of streptomycin treatment. Detection of ototoxicity according to the duration of streptomycin treatment was compared between DPOAE and PTA.

RESULTS

Of 96 newly diagnosed patients treated with streptomycin, 50 completed the study. During the treatment period, 62.5% of the patients had vertigo, while 37.5% complained of tinnitus. DPOAE detected ototoxicity in 47.7% of the cases at day 7, 66.0% at day 14, 70.0% at day 28 and 77.1% at day 56 of streptomycin treatment. The higher frequencies were affected more by ototoxicity, with significant differences at 8 vs. 9 kHz on all testing days and at 9 vs. 10 kHz except on days 7 and 56 (p < 0.001). Hearing loss was detected by PTA in 2.3% of patients on day 7, in 10.6% on day 14, in 22.0% on day 48 and in 29.2% on day 56.

CONCLUSION

DPOAE is a sensitive tool that can detect early changes in the cochlea due to ototoxicity. Use of DPOAE rather than PTA to screen for ototoxicity could reduce screening time and would allow clinical monitoring of more patients.

The sternalis muscle in cadavers: anatomical facts and clinical significance

The sternalis is an anomalous muscle located in the anterior wall of thorax and several past reports have described its presence with clinical implications. The sternalis muscle may be incidentally detected during routine cadaveric dissections and autopsies. We observed the presence of anomalous sternalis muscle on both sides of the anterior chest wall in 25 cadavers (n = 50), over a span of three years. Out of a 50 cases, we observed a single case of sternalis on the right side of the 55-year-old male cadaver (2%). The sternalis was found to be absent in the rest 49 cases (98%). The sternalis muscle displayed an oblique course in the anterior wall of the thorax. The muscle originated near the seventh costal cartilage extending obliquely upwards to insert into the second costal cartilage close to the sternum. The originating portion of the muscle was located at a distance of 3.5 cm lateral to the mid-sternal plane. The vertical length and the maximum width of the anomalous sternalis muscle measured 9 cm and 1.9 cm, respectively. The fibers of the muscle vertically ascended upwards. No other associated anomalies were observed in the same cadaver. The presence of sternalis muscle is considered to be a rare variation with no earlier studies being performed in the Malaysian population. The anomalous sternalis muscle may be important for reconstructive surgeons performing mastectomy and radiologists interpreting mammograms. Thus, the sternalis muscle may be academically, anthropologically and surgically important.

Maxillofacial trauma with emphasis on soft-tissue injuries in Malaysia

Soft-tissue injuries with or without facial bone involvement are the most common presentation following maxillofacial trauma. The objective of this study was to look at the distribution, pattern and type of soft-tissue injury in relation to aetiology. Records of patients over a period of 5 years (1998-2002), who sustained maxillofacial injuries and were treated at Kajang Hospital, a secondary referral hospital, were reviewed. Out of 313 patients with maxillofacial injuries, 295 patients sustained soft-tissue injuries. Males (79%) between 21 and 30 years old (34%) were the majority of patients. Road-traffic accident was the main cause of soft-tissue injuries (75%) with motorcycle accident being the most frequent (40%). The upper lips (23%) and the lower lips (18%) were the most common extraoral site involved, while the labial mucosa and sulcular areas, both accounting for 21%, were the most common intraoral sites. Stringent road-traffic regulations should be practiced in developing countries, as morbidity arising from road-traffic accidents poses a national economic and social problem.

Use of hecate-chorionic gonadotropin beta conjugate in therapy of lutenizing hormone receptor expressing gonadal somatic cell tumors

Improvement of cancer treatment is a major challenge of medical research. Despite the immense efforts made in the improvement of diagnosis and treatment, cancer remains a major concern and cause of morbidity and mortality. Most of the modern anti-neoplastic therapies have severe side effects, and tumor cells often develop drug resistance. There is promise in the new generation of treatments (gene therapy, immunotherapy, vaccines, etc.) that are under development, but the efficacies and side effects of such therapies have so far been disappointing. Receptor-based therapies are not new, but many normal cells also present the same receptors reducing the specificity of such approaches. Several lytic peptides have been investigated because of they appear to kill cancer cells due to changes of their membrane potential. Thus, linking receptor-specific ligands to lytic peptides is expected to augment the specificity of targeting and decrease the toxicity of lytic peptides on normal cells. One such polypeptide is hecate (an analogue to the bee venom main component, melittin) that preferentially kills cancer cells at low doses. When this peptide is fused with the 81-95 amino acid fragment of chorionic gonadotropin-beta (CGbeta) subunit (hecate-CGbeta), it targets cells expressing luteinizing hormone receptor (LHR), even at very low doses, or when LHR is expressed at low level. Our recent data showed that this peptide conjugate is efficient in destroying LHR-positive cells in xenografts and more importantly in transgenic mouse models developing LHR-positive somatic cell tumors in gonads. The mechanism of action of hecate-CGbeta after binding to LHR is destruction of cell membranes resulting in rapid cell death by necrosis with minimal side effects. This review summarizes our findings on the action of this novel peptide and considers the future potential of this family of targeting peptides in the treatment of neoplasias.

Application of the linear interaction energy method (LIE) to estimate the binding free energy values of Escherichia coli wild-type and mutant arginine repressor C-terminal domain (ArgRc)–l-arginine and ArgRc–l-citrulline protein–ligand complexes

Protein-ligand binding free energy values of wild-type and mutant C-terminal domain of Escherichia coli arginine repressor (ArgRc) protein systems bound to L-arginine or L-citrulline molecules were calculated using the linear interaction energy (LIE) method by molecular dynamics (MD) simulation. The binding behaviour predicted by the dissociation constant (K(d)) calculations from the binding free energy values showed preferences for binding of L-arginine to the wild-type ArgRc but not to the mutant ArgRc(D128N). On the other hand, L-citrulline do not favour binding to wild-type ArgRc but prefer binding to mutant ArgRc(D128N). The dissociation constant for the wild-type ArgRc-L-arginine complex obtained in this study is in agreement with reported experimental results. Our results also support the experimental data for the binding of L-citrulline to the mutant ArgRc(D128N). These showed that LIE method for protein-ligand binding free energy calculation could be applied to the wild-type and the mutant E. coli ArgRc-L-arginine and ArgRc-L-citrulline protein-ligand complexes and possibly to other transcriptional repressor-co-repressor systems as well.

Localization of bovine serum albumin in double-walled microspheres

Phase separation of binary blends of various combinations of poly (L-lactide) (PLA), and poly (D,L-lactide-co-glycolide) (PLGA), was investigated using differential scanning calorimetry (DSC). Based on this phase separation phenomenon, double-walled microspheres were fabricated. A model agent, bovine serum albumin (BSA) labeled with fluorescein isothiocyanate (FITC-BSA) was localized in each layer. Scanning electron microscopy (SEM) and fluorescence microscopy (FM) were used to assess the formation of double-walled microspheres and the localization of the drug, respectively. When a 1:1 polymer ratio was used, the FITC-BSA was localized in the outer layer. When the relative ratio of PLGA to PLA was increased to 3:1 using the same overall polymer concentration, the FITC-BSA was localized in the inner core. Release studies were carried out to evaluate the advantage of double-walled microspheres compared to single walled microspheres. Microspheres made with FITC-BSA localized in the inner core exhibited a significantly lower initial release rate compared to microspheres where the drug was located in the outer layer, or compared to microspheres made from PLA only. Hence microspheres with a double-walled morphology have the potential for therapeutic use where a high burst might be detrimental.

Adrenocortical tumorigenesis in transgenic mice: the role of luteinizing hormone receptor and transcription factors GATA-4 and GATA-61

Transgenic (TG) mice, bearing the Simian Virus 40 T-antigen (Tag) under a 6-kb fragment of the murine inhibin alpha-subunit promoter (inhalpha), develop gonadal tumors of granulosa or Leydig cell origin with 100% penetrance by the age of 5-7 months. When these TG mice were gonadectomized prepubertally, between 21-25 days of life, adrenal gland tumors were observed in each mouse by the age of 5-7 months. No adrenal tumors were detected in any intact TG, gonadectomized or intact or control non-TG littermates. The adrenocortical tumors appeared to originate from the X-zone of the adrenal cortex. If functional gonadectomy was induced by GnRH antagonist treatment or by cross-breeding of the TG mice into hypogonadotropic hpg genetic background, neither gonadal nor adrenal tumorigenesis appeared. This prompted a hypothesis that adrenal tumor development in inhalpha/Tag TG mice is related to elevated gonadotropin secretion, which is the most obvious difference between the surgical and functional gonadectomy models. The adrenal tumors and a cell line (Calpha1) derived from them, was found to express luteinizing hormone receptor (LHR), but no FSHR, and hCG treatment stimulated their proliferation. No FSHR was found in the adrenal glands. On the basis of this it was suggested that expression of the potent oncogene T-antigen, allow LH in adrenocortical cells to function as a tumor promoter, and induction of high level functional LHR expression in adrenal tumors. Given the induction of expression and regulation of the GATA-4 and GATA-6 zinc finger family of transcription factors in the gonads by gonadotropins, it was in our interest to explore their expression in the adrenals. We utilized the inalpha/Tag TG mouse model and pathological human adrenal samples to explore the role of GATA-4 and GATA-6 in adrenocortical tumorigenesis. Abundant GATA-6 mRNA expression was found in normal control adrenal cortex during mouse development, whereas GATA-4 mRNA was undetectable. In striking contrast to this, GATA-6 was absent from murine adrenocortical tumors, while GATA-4 mRNA expression was dramatically upregulated in the murine adrenal tumors as well as in human adrenocortical carcinomas. Taken together, these results suggest different roles for GATA-4 and GATA-6 in the adrenal gland, and implicate GATA-4 in adrenal LHR expression and tumorigenesis. Immunohistochemical detection of GATA-4 may serve as a useful marker in differential diagnosis of human adrenal tumors. In addition, the inhalpha/Tag TG model will be helpful for exploring the molecular mechanisms underlying adrenocortical tumorigenesis, ectopic LHR expression in adrenals and the GATA-4/LHR interaction that is related to adrenal tumorigenesis in TG mice.

Gonadal tumors of mice double transgenic for inhibin-alpha promoter-driven simian virus 40 T-antigen and herpes simplex virus thymidine kinase are sensitive to ganciclovir treatment

We have previously produced transgenic (TG) mice expressing the mouse inhibin alpha-subunit promoter/Simian virus 40 T-antigen (Inhalpha/Tag) fusion gene. The mice develop gonadal somatic cell tumors at the age of 5-7 months; the ovarian tumors originate from granulosa cells, and those of the testes from Leydig cells. In the present study another TG mouse line was produced, expressing under the same inh-alpha promoter the herpes simplex virus thymidine kinase gene (Inhalpha/TK). Crossbreeding of the two TG mouse lines resulted in double TG mice (Inhalpha/TK-Inhalpha/Tag), which also developed gonadal tumors. The single (Inhalpha/Tag) and double TG (Inhalpha/TK-Inhalpha/Tag) mice, both bearing gonadal tumors, were treated at the age of 5.5-6.5 months with ganciclovir (GCV, 150 mg/kg body weight twice daily i.p.) for 14 days, or with aciclovir (ACV, 300-400 mg/kg body weight per day perorally) for 2 months. During GCV treatment, the total gonadal volume including the tumor, decreased in double TG mice by an average of 40% (P<0.05), while in single TG mice, there was a concomitant increase of 60% in gonadal size (P<0.05). GCV was also found to increase apoptosis in gonads of the double TG mice. Peroral treatment with ACV was less effective, it did not reduce significantly the gonadal volume. We also analyzed the in vitro efficacy of ACV and GCV treatments in transiently HSV-TK-transfected KK-1 murine granulosa tumor cells, originating from a single-positive Inhalpha/Tag mouse. GCV proved to be more effective and more specific than ACV in action. These results prove the principle that targeted expression of the HSV-TK gene in gonadal somatic cell tumors is potentially useful for tumor ablation by antiherpes treatment. The findings provide a lead for further development of somatic gene therapy for gonadal tumors.

Inhibin binding sites and proteins in pituitary, gonadal, adrenal and bone cells

Activin signals via complexes of type I (50-55 kDa) and II (70-75 kDa) activin receptors, but the mechanism of inhibin action is unclear. Proposed models range from an anti-activin action at the type II activin receptor to independent actions involving putative inhibin receptors. Two membrane-embedded proteoglycans, betaglycan and p120, have recently been implicated in inhibin binding, but neither appears to be a signalling receptor. The present studies on primary cultures of rat pituitary and adrenal cells, and several murine and human cell lines were undertaken to characterise inhibin binding to its physiological targets. High affinity binding of inhibin to the primary cultures and several of the cell lines, like that previously described for ovine pituitary cells, was saturable and reversible. Scatchard analysis revealed two classes of binding sites (K(d) of 40-400 and 500-5000 pM, respectively). Affinity labelling identified [125I]inhibin binding proteins with apparent molecular weights of 41, 74, 114 and >170 kDa in all cell types that displayed high affinity, high capacity binding of inhibin. Additional labelling of a 124 kDa species was evident in gonadal TM3 and TM4 cell lines. In several cases, activin (> or =20 nM) competed poorly or not at all for binding to these proteins. The 74, 114 and >170 kDa inhibin binding proteins in TM3 and TM4 cells were immunoprecipitated by an anti-betaglycan antiserum. These three proteins correspond in size to the activin receptor type II and the core protein and glycosylated forms of betaglycan, respectively, that have been proposed to mediate anti-activin actions of inhibin, but the identity of the 74 kDa species is yet to be confirmed. Studies of [125I]inhibin binding kinetics and competition for affinity labelling of individual binding proteins in several cell lines suggest these three species and the 41 and 124 kDa proteins form a high affinity inhibin binding complex. In summary, common patterns of inhibin binding and affinity labelling were observed in inhibin target cells. Novel inhibin binding proteins of around 41 and 124 kDa were implicated in the high affinity binding of inhibin to cells from several sources.

Ovarian tumorigenesis in mice transgenic for murine inhibin alpha subunit promoter-driven Simian Virus 40 T-antigen: ontogeny, functional characteristics, and endocrine effects

We previously reported formation of ovarian granulosa cell tumors with 100% penetration in a transgenic mouse model with murine inhibin alpha subunit promoter-driven (inhalpha)/Simian Virus 40 T-antigen (Tag). The tumor-bearing inhalpha/Tag mice showed highly elevated serum levels of immunoreactive inhibin. To investigate the onset of tumorigenesis and related endocrine consequences, 6-8 female mice of two inhalpha/Tag lines and their mating control littermates were killed monthly between 1 and 6 mo of age. We also investigated tumorigenesis-related fertility aspects of these two mouse lines. The ontogeny and progression of tumors could be monitored in both inhalpha/Tag lines by alterations of ovarian weights and serum hormone levels. Serum progesterone levels increased in both inhalpha/Tag lines in an age-dependent manner as ovarian tumorigenesis progressed, and a reciprocal decrease occurred in serum LH and FSH. Neither serum estradiol (E(2)) nor uterine weights were significantly altered during tumorigenesis, suggesting that the ovarian tumors represented late stages of granulosa cell differentiation. In conclusion, the present findings show in the inhalpha/Tag TG mice a relation between endocrine consequences of granulosa cell tumorigenesis, and a connection of onset of tumor formation with aberrant steroidogenesis and gonadotropin secretion. These findings indicate that tumors are endocrinologically active and able to exert enhanced negative feedback effects on pituitary function. The tumors provide a good model for endocrinologically active hormone-dependent tumors.

Hormonal regulation of proliferation of granulosa and Leydig cell lines derived from gonadal tumors of transgenic mice expressing the inhibin-alpha subunit promoter/simian virus 40 T-antigen fusion gene

We have produced a transgenic (TG) mouse model expressing the Simian Virus 40 T-antigen (Tag) gene, driven by a 6-kb fragment of the mouse inhibin-alpha subunit promoter (inh-alpha). The mice develop gonadal tumors with 100% penetrance by the age of 5-8 months, of granulosa cell origin in the ovary, and of Leydig cell origin in the testis. In the present study, we characterized the hormonal regulation of proliferation of two immortalized cell lines, BLT-1, originating from a Leydig cell tumor, and NT-1, originating from a granulosa cell tumor. [3H]-thymidine incorporation in both types of cells was stimulated by activin (> or = 10-30 microg/l), while inhibin had no effect. Transforming growth factor (TGF)-beta, at > or = 0.01 microg/l, stimulated proliferation of the granulosa tumor cells, but no effect was found on the Leydig tumor cells. Progesterone inhibited the proliferation of both cell lines, although the granulosa tumor cells were clearly less sensitive than the Leydig cells to this effect ( > or = 3 micromol/l vs. > 10 nmol/l, respectively). hCG had no effect on the Leydig tumor cell DNA synthesis whereas at high concentration (100 microg/l) it stimulated that of the granulosa cells. We also investigated in BLT-1 and NT-1 cells whether the proliferative changes were related to concomitant changes in Tag expression. In BLT-1 cells, this was stimulated by activin, progesterone and hCG, even though the latter substance did not affect cell proliferation. In contrast, TGF-beta inhibited Tag expression. In NT-1 cells, the expression of Tag was stimulated by activin, while hCG had no effect. In contrast, it was reduced by progesterone, inhibin and TGF-beta. In conclusion, our results indicate that the granulosa and Leydig tumor cells, despite similar mechanism of immortalization, respond differently to several mitotic stimuli. The responses in the level of Tag expression in these cells did not always correlate with the changes observed in cell proliferation, indicating the independence of these two phenomena.

Transgenic mouse models for gonadal tumorigenesis

The versatile transgenic (TG) techniques allow the production of in vivo animal models for a variety of diseases, including malignant tumors, through tissue-specific expression of oncogenes. We have created a TG mouse model for gonadal somatic cell tumors by expressing the powerful viral oncogene, Simian virus 40 T-antigen (Tag) under regulation of the murine inhibin alpha-subunit promoter (inh alpha). Ovarian granulosa and theca cell tumors were formed in the female, and those of testicular Leydig cells, in the male TG mice at the age of 5-6 months, with 100% penetrance. The tumors produced high levels of inhibin peptides, especially the alpha-subunit, and were steroidogenically active, mainly producing progesterone. The gonadal tumorigenesis was gonadotropin-dependent, since TG mice rendered gonadotropin-deficient by crossbreeding them into the hypogonadotropic hpg genetic background, or by treating them with a gonadotropin-releasing hormone (GnRH) antagonist, did not develop tumors. In order to study the possibility of using the tumor mouse model for testing gene therapy, we created another TG mouse model expressing under the same inhibin-alpha promoter the Herpes Simplex virus (HSV) thymidine kinase (TK) transgene. The inh alpha/HSV-TK mice were crossbred with the inh alpha/Tag mice and the double mutant mice also developed gonadal tumors. When they were treated with antiherpes drugs (acyclovir or gancyclovir), further growth of the tumors was blocked. These preliminary findings prove the principle that tumor ablation in our TG mouse model can be achieved by transduction of the HSV-TK gene into the tumor cells. Besides studies of formation, regulation and therapy of the tumors in vivo, immortalized cell lines derived from them provide models for studies of gonadal somatic cell functions in vitro.

Intracranial tuberculoma in Kuwait

OBJECTIVE

To study the manifestations of intracranial tuberculoma in Kuwait and to provide guidelines for the diagnosis and management of intracranial tuberculoma in developing countries, where the disease is common and facilities are limited.

DESIGN

Data were collected from patients with intracranial space-occupying lesions admitted to Adan Hospital Medical Department and the Neurosurgery and Neuromedical Departments at Ibn-Sina Hospital, Kuwait, from January 1987 to December 1995.

RESULTS

Intracranial tuberculomas represented 1.4% of all cases with intracranial space-occupying lesions in these hospitals (13/925); 77% of the patients were males, and seizures were the most frequent presenting symptom. Nine patients (66.6%) responded well to medical treatment and four (33.3%) failed to respond. Those who responded to medical treatment showed remarkable improvement of the intracranial lesions within 6 weeks, and almost complete resolution within 12 weeks. Seven patients required surgery, three due to failure of medical treatment. We report a patient who needed emergency shunt operation, a patient with pituitary tuberculoma, and two patients whose lesions recurred several years after surgery.

CONCLUSION

Bearing in mind the non-specific nature of computed tomography and magnetic resonance imaging in the diagnosis of intracranial tuberculoma, and the lack of advanced neurosurgical facilities in developing countries where the disease is common, we recommend a 6-week therapeutic test for patients with solitary or multiple enhancing intracranial space-occupying lesions without mass effect. Stereotactic biopsy is recommended in selected cases wherever facilities are available.

Luteinizing hormone receptors are associated with non-receptor plasma membrane proteins on bovine luteal cell membranes

Biophysical studies of the bovine luteinizing hormone (LH) receptor on luteal cell membranes suggest that this receptor may be part of a larger molecular weight structure. We have used 5-iodonaphthyl-1-azide (INA) to identify plasma membrane proteins near LH receptors on plasma membranes from bovine corpora lutea. Following binding of eosin isothiocyanate-derivatized ovine LH or human chorionic gonadotropin (hCG), five proteins with molecular weights of 71, 57, 55, 49 and 36 kDa were selectively derivatized with [125I]-INA following 2 h exposure at 22 degreesC to 514 nm light. However, there was no fluorescence energy transfer between LH receptors occupied by ovine LH or hCG indicating that LH receptors were not self-associated in these membrane preparations. Together these results suggest that, following hormone binding, single copies of the LH receptor may exist in large molecular weight structures that include non-receptor proteins.

Expression and hormonal regulation of transcription factors GATA-4 and GATA-6 in the mouse ovary

Two members of the GATA-binding family of transcription factors, GATA-4 and GATA-6, are expressed in the vertebrate ovary. To gain insight into the role of these factors in ovarian cell differentiation and function, we used in situ hybridization to determine the patterns of expression of GATA-4 and GATA-6 in mouse ovary during development and in response to hormonal stimulation. GATA-4 messenger RNA (mRNA) was first evident in the ovary around the time of birth. In the adult ovary, abundant GATA-4 mRNA was detected in granulosa cells of primary and antral follicles, with lesser amounts of GATA-4 message detected in theca cells, germinal epithelium, and interstitial cells. Little or no GATA-4 mRNA was found in corpus luteum. GATA-6 message exhibited a different distribution in the ovary, with abundant expression evident in both granulosa cells and corpora lutea. Stimulation of 3-week-old females with PMSG or estrogen enhanced follicular expression of GATA-4 and GATA-6 transcripts. Subsequent induction of ovulation with human CG resulted in a decrease in GATA-4 mRNA expression in granulosa cells, whereas GATA-6 mRNA expression persisted in granulosa cells after ovulation and in corpora lutea. Moreover, follicular apoptosis was associated with a decrease in the expression of GATA-4 but not GATA-6 message. Stimulation of cultured gonadal cell lines with FSH resulted in increased expression of GATA-4 message, whereas GATA-6 mRNA expression was not affected. In light of these findings, the established role of other GATA-binding proteins in hematopoetic cell differentiation and apoptosis, and the presence of conserved GATA motifs in the promoters of genes expressed selectively in ovary, we propose that GATA-4 and GATA-6 play distinct roles in follicular development and luteinization.

Cytology of Ki-1-positive anaplastic large cell lymphoma. A report of two cases

BACKGROUND

Ki-1-positive anaplastic large cell lymphoma (Ki-1 ALCL), one of the more recently described pleomorphic types of lymphoma, affects mostly children and adolescents and is sometimes mistaken for carcinoma or sarcoma.

CASES

Two cases of Ki-1 ALCL were diagnosed on cytology. One patient presented with generalized lymph-adenopathy and involvement of the skin and subcutis, while the other was admitted with pneumonia and multiple subcutaneous masses in the chest wall. Fine needle aspiration cytology smears in both cases showed dissociated cells with abundant, lightly basophilic, vacuolated cytoplasm; oval, round or lobulated nuclei; and binucleate, trinucleate and multinucleate cells with a wreathlike arrangement of nuclei. Most of the tumor cells expressed immunocytologic reactivity to CD 30, and a cytologic diagnosis of Ki-1 ALCL was made. Tru-cut biopsy of the chest wall tumor in case 2 and review of lymph node biopsy done one year previously in case 1 permitted a cytohistologic correlation.

CONCLUSION

Knowledge of the distinctive cytomorphologic features of Ki-1 ALCL combined with the clinical setting should enable its distinction from other pleomorphic neoplasms in most cases, while in others it should go a long way toward narrowing the cytologic differential diagnosis.

5-iodonaphthyl-1-azide labeling of plasma membrane proteins adjacent to specific sites via energy transfer

We have examined conditions optimal for 5-iodonaphthyl-1-azide (INA4) labeling of membrane proteins proximal to known membrane sites. Membrane-bound INA can be indirectly activated by energy transfer from visible chromophores. We demonstrate that the efficiency of this sensitized activation is enhanced by use of triplet-forming chromophores such as eosin and by deoxygenation. Variation of sensitized activation efficiency with INA concentration indicates that the critical distance for eosin-INA energy transfer in solution is 8-14 A. We suggest that photosensitization occurs through triplet exchange and present an improved labeling protocol based on these findings. This protocol was used to examine whether different accessory proteins are associated with isolated and crosslinked Type I Fc epsilon receptors on 2H3 rat basophilic leukemia cells. 2H3 cells were incubated with eosin-conjugated IgE and irradiated at 514 nm yielding [125I]INA derivatized peptides at 53, 38, 34, and 29 kDa. Crosslinking IgE with mouse anti-rat IgE prior to irradiation labeled three additional proteins at 60, 54, and 43 kDa. These results demonstrate the utility of sensitized INA labeling in characterizing protein-protein interactions in membranes of intact cells and indicate the importance of considering photophysical factors when selecting sensitizers and reaction conditions. We discuss estimation of the size of the membrane region surrounding a sensitizing chromophore within which INA labeling of membrane proteins occurs.

Enlarged spectrum of seminological diagnoses using the resazurin colour reaction; a spectrophotometric application

Two sets of investigations were carried out in the present study to establish whether, in semen samples processed for the resazurin reaction (RT), the colour change and its intensity were informative for both the quality and quantity of spermatozoa. First, the results of RT were read visually using single semen samples from 42 consecutive men from infertile couples. In the second step, the results were additionally read using a spectrophotometer. Single semen samples obtained from another 87 consecutive men from infertile couples and 12 men from fertile couples were analysed in this step. Visual analysis, which involved grading against and RT colour chart, revealed a significant positive correlation between the RT results and the quantity and quality of spermatozoa. Azoospermia was diagnosed by grade number 1 (dark purple colour), while the highest grades 8-11 (colours dark red to pink) represented a homogeneous group of patients with the highest quality of spermatozoa (> 60% motility) and quantity (> 60 x 10(6)/ml ejaculate). Normal parameters of spermatozoa, according to WHO, appeared with a high predominance (89-100% of cases) in this group and were present in most of the samples. Thus, the grades 8-11 might represent semen samples with optimal fertility potential. Spectrophotometric analysis of RT revealed that visual characteristics corresponded closely to the values for optical density (OD) of the samples. The OD for normozoospermic samples ranged between 1.48 and 1.84; for oligozoospermia between 1.2 and 1.48; for azoospermia between 0.98 and 1.1. The OD for samples with putative optimal fertility potential ranged between 1.6 and 1.84. RT evaluation using a spectrophotometer may therefore provide a tool for obtaining a wider spectrum of seminological diagnoses than classic microscopic examination, especially for distinguishing men with probable optimal fertility potential.

Helicobacter pylori eradication with short-term therapy leads to duodenal ulcer healing without the need for continued acid suppression therapy

OBJECTIVE

To determine whether duodenal ulcers continue to heal following successful Helicobacter pylori eradication with short-term eradication therapy without further acid suppression therapy.

METHODS

Patients with endoscopically proven duodenal ulcers who were H. pylori positive were randomized to receive omeprazole 40 mg each morning and clarithromycin 500 mg three times daily or famotidine 40 mg twice daily and clarithromycin 500 mg three times daily for 2 weeks. No acid-suppressing agents nor ulcerhealing drugs such as bismuth compounds or sucralfate were prescribed after that. Patients were re-examined endoscopically at week 2 at the end of treatment, and at week 6, 4 weeks after the completion of treatment.

RESULTS

Thirty of 44 (68.2%) patients from both treatment arms, in whom the bacteria were subsequently noted to have been eradicated, had healed ulcers at week 2; at Week 6, 42 of 44 (95.5%) were noted to have healed ulcers without further acid-suppressing or ulcer-healing treatment.

CONCLUSION

Although a short-term acid-suppressing treatment is insufficient to heal ulcers, where an important putative factor such as H. pylori is eliminated, the ulcer healing process continues without further need for acid-suppressing or ulcer-healing agents.

Rotational dynamics of luteinizing hormone receptors on bovine and ovine luteal cell plasma membranes

To determine whether LH receptor rotational diffusion is similar in closely related species, we compared the rotational correlation times of LH receptors on bovine CL membranes with those of LH receptors on sheep small luteal cells and luteal cell plasma membranes using time-resolved phosphorescence anisotropy techniques. After binding of erythrosin isothiocyanate (ErITC)-derived bovine LH (bLH), ErITC-ovine LH (oLH), or ErITC-hCG, there was no difference in the initial and final anisotropy at 4 degrees C, 15 degrees C, 25 degrees C, and 37 degrees C, indicating that the bLH receptor was rotationally immobile on the time scale of our experiments. On these same membrane preparations, the epidermal growth factor (EGF) receptor occupied by ErITC-murine EGF exhibited temperature-dependent rotational correlation times of 80 +/- 5 microseconds, 111 +/- 7 microseconds, 254 +/- 4 microseconds, and > 1000 microseconds at 4 degrees C, 15 degrees C, 25 degrees C, and 37 degrees C, respectively. Slower rotational times for EGF receptor observed at higher temperatures suggested the occurrence of temperature-dependent receptor aggregation. Like the bLH receptor, the oLH receptor on intact cells and on CL plasma membranes was rotationally immobile on the time scale of our experiments when occupied by ErITC-hCG. However, the oLH-occupied receptors on small luteal cells and on luteal cell membranes had comparable rotational correlation times at 37 degrees C. These results suggest that bLH receptors are present in large, rotationally immobile structures, whereas the receptor-containing structure formed on ovine luteal cells depends on whether that receptor is occupied by hCG or oLH. Also, despite the similarities between reproductive function in these species, the LH-occupied receptor appears to be organized differently in the plasma membranes of these hormone-responsive luteal cells.

Rotational dynamics of luteinizing hormone receptors and MHC class I antigens on murine Leydig cells

We have examined the molecular motions of luteinizing hormone (LH) receptor and the Major Histocompatibility Complex Class I antigen on murine Leydig cells. Using time-resolved phosphorescence anisotropy methods, erythrosin (ErITC)-derivatized ovine luteinizing hormone (oLH) bound to the LH receptor appears rotationally mobile with rotational correlation times of 19.6 +/- 1.3 microseconds, 13.3 +/- 2.4 microseconds, 9.5 +/- 0.7 microseconds and 4.7 +/- 0.5 microseconds at 4 degrees C, 15 degrees C, 25 degrees C and 37 degrees C, respectively. Rotational correlation times for human chorionic gonadotropin (hCG)-occupied LH receptors were similar to those of the ErITC-oLH occupied receptor at each temperature. In addition, both oLH- and hCG-occupied LH receptors were laterally mobile in fluorescence photobleaching recovery experiments with diffusion coefficients at 29 degrees C of (5.8 +/- 0.9) x 10(-10) cm2 s-1 and (2.9 +/- 0.4) x 10(-10) cm2 s-1, respectively. We also measured the rotational correlation time of Class I antigen on murine Leydig cells using ErITC-derivatized 34-12-2S, an anti-Class I monoclonal antibody. Because there was no decay of the anisotropy function at 4 degrees C, 15 degrees C, 25 degrees C or 37 degrees C in the absence of oLH or following preincubation of Leydig cells with 1 nM oLH, it appears that Class I is rotationally immobile on the 1 ms timescale of our experiments. This result is consistent with the presence of Class I antigen in large molecular weight structures and may be the result of Class I self-aggregation. Further, treatment of cells with anti-Class I antibody had no effect on either basal or oLH-stimulated testosterone secretion. Thus, it appears that this anti-Class I antibody is not LH-mimetic on murine Leydig cells.

The accumulation and distribution of trace metals in some localized marine species

Trace elements, such as As, Co, Cr, Hg, Sb, and Zn, were determined by neutron activation analysis (NAA), whereas Cd, Cu, and Pb were determined by graphite furnace atomic absorption spectroscopy (GFAAS) in clam, crab, prawn, swamp cerith, and mussel samples after digestion by microwave heating under controlled conditions before eluting the solutions through a column of a chelating resin, Chelex-100. The standard used in the determination of percentage volatile elements retained by microwave digestion and also in the activation process was Lobster Hepatopancreas TORT-1, whereas known mixed standards were prepared from nitrate salts to determine the efficiency of the separation procedure at a controlled pH. Mercury and lead detected in crabs exceeded the maximum permissible level. Some species also showed a high affinity toward certain elements, and their levels of accumulation in the tissues of these species corresponded with the concentration of these elements in sediments, especially at sites in the vicinity of an industrial zone.

Class I major histocompatibility complex antigens are not associated with the LH/CG receptor on ovine luteal cells

We have examined the rotational dynamics of the luteinizing hormone (LH) receptor on day 10 intact ovine small luteal cells and isolated plasma membranes using polarized fluorescence depletion (PFD). This technique measures rotational correlation times which are proportional to the in-membrane volume of a protein and are useful for examining changes in protein size due to receptor aggregation or protein-protein interactions. Eosin isothiocyanate (EITC)-derivatized ovine LH (EITC-oLH) bound to the LH receptor on luteal cell plasma membranes had a rotational correlation time of 20 +/- 6 microseconds, while that for EITC-human chorionic gonadotropin (EITC-hCG)-occupied LH receptors was 46 +/- 13 microseconds. Slower rotational times for EITC-oLH and EITC-hCG, 63 +/- 19 and 87 +/- 20 microseconds, respectively, were obtained on intact ovine luteal cells. These results indicate that the LH receptor exists as a larger molecular mass complex when binding hCG than oLH, a difference which could be attributable to hCG-induced LH-receptor interaction with additional membrane protein(s). One candidate protein for such an interaction is the Major Histocompatibility Complex (MHC) Class-I antigen. However, the rotational correlation time of EITC-anti-MHC Class-I antibody (SBU I) Fab fragments was 247 +/- 34 microseconds, indicating that MHC Class I is located in complexes larger than those identified by EITC-OLH or EITC-hCG. Preincubation of plasma membranes with 1 nM unlabeled oLH or hCG had no significant effect on this rotational correlation time. Further, treatment of cells with SBU I had no affect on either basal or oLH-stimulated progesterone secretion. Thus it appears that the ovine luteal LH-receptor is not associated with MHC Class I and that antibody-induced aggregation of MHC Class I does not cause an LH-mimetic response.

Fluorescence depletion measurements in various experimental geometries provide true emission and absorption anisotropies for the study of protein rotation

Use of fluorescence depletion methods for measuring slow protein rotational diffusion has been limited by failure to obtain, from depletion data, well-defined anisotropy functions dependent on the distribution of either fluorophore emission or absorption transition dipoles, but not both. Such anisotropies would be directly comparable to those obtained from phosphorescence emission or triplet absorption measurements. We now describe such procedures applicable to cuvet and microscope experimental geometries, together with supporting experimental results. In cuvet measurements, the pump and probe beams are colinear and fluorescence is collected at 90 degrees to this axis. The data analysis procedure for this geometry has been suggested by Wegener (Biophys. J., 46 (1984) 795) and permits calculation of the absorption and emission anisotropies and the interdipole angle. In microscope experiments, fluorescence emission is collected along the pump/probe beam axis. For microscope measurements, a new experimental procedure permits evaluation of absorption and emission anisotropies when the interdipole angle is independently known. In either case multiple depletion measurements are required, each with different relative orientations of the probe beam polarization, pump beam polarization and emission polarizer axis. We have used these methods to calculate the time-dependent anisotropies for eosin-derivatized BSA rotation in glycerol solutions in both experimental geometries. These data correspond well with those obtained from time-resolved phosphorescence anisotropy measurements.

Molecular dynamics of luteinizing hormone receptors on rat luteal cells

To better understand the in situ organization of the luteinizing hormone receptor on rat luteal cells, we have examined the molecular motions of this receptor following binding of ovine luteinizing hormone (oLH) or human chorionic gonadotropin (hCG). Fluorescence photobleaching recovery (FPR) measurements of LH receptor lateral diffusion were performed using tetramethylrhodamine isothiocyanate (TRITC)-derivatized oLH or hCG as a probe. These experiments indicate that TRITC-oLH occupied LH receptors on luteal cells obtained from superovulated female rats have a lateral diffusion coefficient D of (1.7 +/- 0.6).10(-10) cm2s-1 at 27 degrees C with fluorescence recovery after photobleaching of 46 +/- 5%. In similar experiments, binding of TRITC-hCG caused a significant decrease in LH receptor lateral diffusion; fluorescence recovery after photobleaching was less than 20%. To determine whether hCG-occupied receptors might exist in large aggregates, we measured the rotational correlation times (RCT) of hCG and oLH bound to the LH receptor on intact cells using single cell polarized fluorescence depletion (PFD). At 4 degrees C, LH receptors occupied by eosin isothiocyanate (EITC)-hCG exhibited a slower RCT (64 microseconds) than did receptors occupied by EITC-oLH (43 microseconds). At this temperature both TRITC-oLH and TRITC-hCG occupied LH receptors were laterally immobile. These FPR and PFD results suggest that the molecular motions of the luteal cell LH receptor are significantly modulated by the subtle structural differences in various bound gonadotropins.

Self-association of class I major histocompatibility complex molecules in liposome and cell surface membranes

Fluorescent derivatives of a human MHC class I glycoprotein, HLA-A2, were reconstituted into dimyristoylphosphatidylcholine (DMPC) liposomes. Measurements of lateral diffusion of fluorescein-(Fl-) labeled HLA-A2 by fluorescence photobleaching recovery (FPR), of rotational diffusion of erythrosin-(Er-) labeled HLA-A2 by time-resolved phosphorescence anisotropy (TPA), and of molecular proximity by flow cytometric fluorescence resonance energy transfer (FCET) showed that these class I MHC molecules self-associate in liposome membranes, forming small aggregates even at low surface concentrations. The lateral diffusion coefficient (Dlat) of Fl-HLA-A2 decreases with increasing surface protein concentration over a range of lipid:protein molar ratios (L/P) between 8000:1 and 2000:1. The reduction in Dlat of HLA molecules in DMPC liposomes is found to be sensitive to time and temperature. The rotational correlation time for Er-HLA-A2 in DMPC liposomes at 30 degrees C is 87 +/- 0.8 microseconds, at least 10 times larger than that expected for an HLA monomer. There is also significant quenching of donor (Fl-HLA) fluorescence at 37 degrees C in the presence of acceptor-labeled (sulforhodamine-labeled HLA) protein indicating proximity between HLA molecules even at L/P = 4000:1. FPR and FCET measurements with another membrane glycoprotein, glycophorin, give no evidence for its self-association. HLA aggregation measured by FPR, FCET, and TPA was blocked by beta 2-microglobulin, b2m, added to the liposomes. The aggregation of HLA-A2 molecules is not an artifact of their reconstitution into liposomes. HLA aggregates, defined by FCET, were readily detected on the surface of human lymphoblastoid (JY) cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Rotational dynamics of type I Fc epsilon receptors on individually-selected rat mast cells studied by polarized fluorescence depletion

We report the first application of polarized fluorescence depletion (PFD), a technique which combines the sensitivity of fluorescence detection with the long lifetimes of triplet probes, to the measurement of membrane protein rotational diffusion on individually selected, intact mammalian cells. We have examined the rotation of type I Fc epsilon receptors (Fc epsilon RI) on rat mucosal mast cells of the RBL-2H3 line in their resting monomeric and differently oligomerized states using as probes IgE and three monoclonal antibodies (mAbs; H10, J17, and F4) specific for the Fc epsilon RI. PFD experiments using eosin (EITC)-IgE show that individual Fc epsilon RI on cells have a rotational correlation time (RCT) at 4 degrees C of 79 +/- 4 microseconds. Similarly, Fc epsilon RI-bound EITC-Fab fragments of the J17 Fc epsilon RI-specific mAb exhibit an RCT of 76 +/- 6 microseconds. These values agree with previous measurements of Fc epsilon RI-bound IgE rotation by time-resolved phosphorescence anisotropy methods. Receptor-bound EITC-conjugated divalent J17 antibody exhibits an increased RCT of 140 +/- 6 microseconds. This is consistent with the ability of this mAb to form substantial amounts of Fc epsilon RI dimers on these cell surfaces. The ratio of limiting to initial anisotropy in these experiments remains constant at about 0.5 from 5 degrees C through 25 degrees C for IgE, Fab, and intact mAb receptor ligands. Extensive cross-linking by second antibody of cell-bound IgE, of intact Fc epsilon RI-specific mAbs or of their Fab fragments, however, produced large fixed anisotropies demonstrating, under these conditions, receptor immobilization in large aggregates. PFD using the mAbs H10 and F4 as receptor probes yielded values for triplet lifetimes, RCT values, and anisotropy parameters essentially indistinguishable from those obtained with the mAb J17 clone. Possible explanations for these observations are discussed.

Acoustic tumors in developing countries

Acoustic tumors are one of the common problems that both the otologist and the neurosurgeon face in Egypt. Early diagnosis and choice of surgical approach--whether middle fossa, translabyrinthine, or suboccipital--are discussed after review of forty-one cases of cerebellopontine angle masses we have seen over the last fifteen years. Particular attention is given to the difficulties in the diagnosis and management of acoustic tumors in developing countries. The reliability of the simple, inexpensive radiologic and audiometric tests is compared with that of the sophisticated CT scanning, polytomography, and brain stem evoked response audiometry. The high operative morbidity and mortality rates in this series are analyzed and the value of microsurgery in total extracapsular tumor resection is stressed.