Identification of membrane dipeptidase as a major glycosyl-phosphatidylinositol-anchored protein of the pancreatic zymogen granule membrane, and evidence for its release by phospholipase A

Membrane dipeptidase (EC 3.4.13.19) enzyme activity that is inhibited by cilastatin has been detected in pancreatic zymogen granule membranes of human, porcine and rat origin. Immunoelectrophoretic blot analysis of human and porcine pancreatic zymogen granule membranes with polyclonal antisera raised against the corresponding kidney membrane dipeptidase revealed that the enzyme is a disulphide-linked homodimer of subunit mass 61 kDa in the human and 45 kDa in the pig. Although membrane dipeptidase was, along with glycoprotein-2, one of the only two major components of carbonate high pH-washed membranes, no enzyme activity or immunoreactivity was detected in the zymogen granule contents. Digestion with bacterial phosphatidylinositol-specific phospholipase C (PI-PLC), and subsequent recognition by antibodies specific for the cross-reacting determinant, revealed that membrane dipeptidase in human and porcine pancreatic zymogen granule membranes is glycosyl-phosphatidylinositol-anchored. Membrane dipeptidase was released from the pancreatic zymogen granule membranes by an endogenous hydrolase, and the released form migrated as a disulphide-linked dimer on SDS/PAGE under non-reducing conditions. Under reducing conditions it migrated with the same apparent molecular mass as the membrane-bound form, and was still a substrate for bacterial PI-PLC. Treatment of kidney microvillar membranes with phospholipase A2 resulted in the release of membrane dipeptidase in a form that demonstrated electrophoretic and cilastatin-Sepharose binding properties identical to those of the endogenously released form of the enzyme from zymogen granule membranes. These results indicate that the glycosyl-phosphatidylinositol anchor on the pancreatic membrane dipeptidase is cleaved by an endogenous hydrolase, probably a phospholipase A, and that this cleavage may promote the release of the protein from the membrane.

Forebrain overgrowth (fog): a new mutation in the mouse affecting neural tube development

Forebrain overgrowth, fog, is a spontaneous autosomal recessive mutation in the mouse producing forebrain, lumbo-sacral, and facial defects. The defects appear to result from excessive growth or cellular proliferation leading to abnormalities in neural tube closure. Three unique features of the mutant are: (1) the growth of telencephalon cells into the surrounding mesenchyme, (2) presence of an encephalocele through the midline cleft in some mutants, and (3) dissociation of the tail defect from the caudal neural tube defect. We used an intersubspecific intercross between mice carrying the fog mutation and mice from an inbred Mus musculus castaneus strain (CAST/Ei) to map the fog mutation to mouse Chromosome 10 near D10Mit262 and D10Mit230 in a region with several potential candidate genes.

Characterization of two alternately spliced forms of phospholipase D1. Activation of the purified enzymes by phosphatidylinositol 4,5-bisphosphate, ADP-ribosylation factor, and Rho family monomeric GTP-binding proteins and protein kinase C-alpha

We previously reported the cloning of a cDNA encoding human phosphatidylcholine-specific phospholipase D1 (PLD1), an ADP-ribosylation factor (ARF)-activated phosphatidylcholine-specific phospholipase D (Hammond, S. M., Tsung, S., Autschuller, Y., Rudge, S. A., Rose, K., Engebrecht, J., Morris, A. J., and Frohman, M. A. (1995) J. Biol. Chem. 270, 29640-29643). We have now identified an evolutionarily conserved shorter splice variant of PLD1 lacking 38 amino acids (residues 585-624) that arises from regulated splicing of an alternate exon. Both forms of PLD1 (PLD1a and 1b) have been expressed in Sf9 cells using baculovirus vectors and purified to homogeneity by detergent extraction and immunoaffinity chromatography. PLD1a and 1b have very similar properties. PLD1a and 1b activity is Mg2+dependent but insensitive to changes in free Ca2+ concentration. Phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate activate PLD1a and 1b but a range of other acidic phospholipids are ineffective. PLD1a and 1b are highly responsive to activation by GTP-gammaS-liganded ADP-ribosylation factor-1 (ARF-1) and can also be activated to a lesser extent by three purified RHO family monomeric GTP-binding proteins, RHO A, RAC-1, and CDC42. Activation of PLD1a and 1b by the RHO family monomeric GTP-binding proteins is GTP-dependent and synergistic with ARF-1. Purified protein kinase C-alpha activates PLD1a and 1b in a manner that is stimulated by phorbol esters and does not require ATP. Activation of PLD1a and 1b by protein kinase C-alpha is synergistic with ARF and with the RHO family monomeric GTP-binding proteins, suggesting that these three classes of regulators interact with different sites on the enzyme.

Immunotoxin therapy of small-cell lung cancer: a phase I study of N901-blocked ricin

PURPOSE

Immunotoxins could improve outcome in small-cell lung cancer (SCLC) by targeting tumor cells that are resistant to chemotherapy and radiation. N901 is a murine monoclonal antibody that binds to the CD56 (neural cell adhesion molecule [NCAM]) antigen found on cells of neuroendocrine origin, including SCLC. N901-bR is an immunoconjugate of N901 antibody with blocked ricin (bR) as the cytotoxic effector moiety. N901-bR has more than 700-fold greater selectivity in vitro for killing the CD56+ SCLC cell line SW-2 than for an antigen-negative lymphoma cell line. Preclinical studies suggested the potential for clinically significant cardiac and neurologic toxicity. We present a phase I study of N901-bR in relapsed SCLC.

PATIENTS AND METHODS

Twenty-one patients (18 relapsed, three primary refractory) with SCLC were entered onto this study. Successive cohorts of at least three patients were treated at doses from 5 to 40 microg/kg/d for 7 days. The initial three cohorts received the first day's dose (one seventh of planned dose) as a bolus infusion before they began the continuous infusion on the second day to observe acute toxicity and determine bolus pharmacokinetics. Toxicity assessment included nerve-conduction studies (NCS) and radionuclide assessment of left ventricular ejection fraction (LVEF) before and after N901-bR administration to fully assess potential neurologic and cardiac toxicity.

RESULTS

The dose-limiting toxicity (DLT) of N901-bR given by 7-day continuous infusion is capillary leak syndrome, which occurred in two of three patients at the dose of 40 microg/kg (lean body weight [LBW])/d. Detectable serum drug levels equivalent to effective in vitro drug levels were achieved at the 20-, 30-, and 40-microg/kg(LBW)/d dose levels. Specific binding of the immunotoxin to tumor cells in bone marrow, liver, and lung was observed. Cardiac function remained normal in 15 of 16 patients. No patient developed clinically significant neuropathy. However, a trend was noted for amplitude decline in serial NCS of both sensory and motor neurons. One patient with refractory SCLC achieved a partial response.

CONCLUSION

N901-bR is an immunotoxin with potential clinical activity in SCLC. N901-bR is well tolerated when given by 7-day continuous infusion at the dose of 30 microg/kg(LBW)/d. Neurologic and cardiac toxicity were acceptable when given to patients with refractory SCLC. A second study to evaluate this agent after induction chemoradiotherapy in both limited- and extensive-stage disease was started following completion of this study.

Differential regulation of extracellular signal-regulated protein kinase 1 and Jun N-terminal kinase 1 by Ca2+ and protein kinase C in endothelin-stimulated Rat-1 cells

The extracellular signal-regulated protein kinase (ERK) and Jun N-terminal kinase (JNK) signalling cascades transduce signals from the cell cytoplasm to the nucleus, where they regulate gene expression. The activation of ERK1 by lysophosphatidic acid (LPA) and endothelin 1 (Et-1) was compared in Rat-1 cells. Both stimulated DNA synthesis to a similar degree but, in contrast with LPA, Et-1 did not stimulate sustained ERK1 activation, a signal that is thought to be important for the proliferation of fibroblasts. Et-1, but not LPA, was able to activate JNK1; pharmacological analysis revealed that the same EtA receptor mediates DNA synthesis, ERK1 and JNK1 activation. However, activation of JNK1 required higher concentrations of Et-1 than was required for stimulation of ERK1 or DNA synthesis. Signalling to ERK1 and JNK1 was partly inhibited by pertussis toxin, suggesting that both pathways are regulated in part by Gi or G0 proteins. Activation of JNK1 by Et-1 lagged behind ERK1 activation but was not dependent on it because PD98059, an inhibitor of mitogen-activated protein kinase (or ERK) kinase, was without effect on JNK1 activation. In contrast with recent studies, activation of protein kinase C (PKC) or Ca2+ fluxes inhibited activation of JNK1 but not ERK1; furthermore inhibition of PKC or sequestration of Ca2+ potentiated JNK1 activation by Et-1 but not by anisomycin, and again had little effect on ERK1 activation. These results demonstrate that the same G-protein-coupled receptor can activate both the ERK and JNK signal pathways but the two kinase cascades seem to be separate, parallel pathways that are differentially regulated by PKC and Ca2+. The results are discussed in terms of the role of ERK and JNK in proliferative signalling.

Involvement of the CD95 (APO-1/Fas) receptor/ligand system in multiple sclerosis brain

Immunohistochemical methods were used to search for Fas receptor/Fas ligand system involvement in multiple sclerosis (MS) white matter brain lesions. We found large numbers of Fas ligand (Fas-L)-bearing cells present in two acute lesions and 12 of 16 chronic MS lesions, and very few positive cells in non-inflammatory controls. Four of six brains from non-MS neuropathologic conditions associated with inflammation and white matter disease were, however, also positive for Fas-L. Double staining with cell-specific markers revealed that the pattern of ligand-positive cells in chronic MS lesions was complex and composed of several different cell types which were primarily resident glial cells with a small overlay of macrophages. Fas/APO 1 (CD95) receptor expression in MS tissue was also evaluated and marked upregulation of the receptor was found. In addition, Fas receptor was induced, but to a lesser extent, in numerous control brains. The observations that TUNEL-positive dying cells were present in MS lesions and showed excellent co-localization with Fas-L, indicate that the Fas death system may contribute to plaque pathogenesis and could lead to the development of a new category of therapeutic agents for MS.

A comparison of two murine monoclonal antibodies humanized by CDR-grafting and variable domain resurfacing

The variable domain resurfacing and CDR-grafting approaches to antibody humanization were compared directly on the two murine monoclonal antibodies N901 (anti-CD56) and anti-B4 (anti-CD19). Resurfacing replaces the set of surface residues of a rodent variable region with a human set of surface residues. The method of CDR-grafting conceptually consists of transferring the CDRs from a rodent antibody onto the Fv framework of a human antibody. Computer-aided molecular modeling was used to design the initial CDR-grafted and resurfaced versions of these two antibodies. The initial versions of resurfaced N901 and resurfaced anti-B4 maintained the full binding affinity of the original murine parent antibodies and further refinements to these versions described herein generated five new resurfaced antibodies that contain fewer murine residues at surface positions, four of which also have the full parental binding affinity. A mutational study of three surface positions within 5 A of the CDRs of resurfaced anti-B4 revealed a remarkable ability of the resurfaced antibodies to maintain binding affinity despite dramatic changes of charges near their antigen recognition surfaces, suggesting that the resurfacing approach can be used with a high degree of confidence to design humanized antibodies that maintain the full parental binding affinity. By comparison CDR-grafted anti-B4 antibodies with parental affinity were produced only after seventeen versions were attempted using two different strategies for selecting the human acceptor frameworks. For both the CDR-grafted anti-B4 and N901 antibodies, full restoration of antigen binding affinity was achieved when the most identical human acceptor frameworks were selected. The CDR-grafted anti-B4 antibodies that maintained high affinity binding for CD19 had more murine residues at surface positions than any of the three versions of the resurfaced anti-B4 antibody. This observation suggests that the resurfacing approach can be used to produce humanized antibodies with reduced antigenic potential relative to their corresponding CDR-grafted versions.

Onset of protective immunity in chicks after vaccination with a recombinant herpesvirus of turkeys vaccine expressing Newcastle disease virus fusion and hemagglutinin-neuraminidase antigens

The onset of protective immunity from lethal Newcastle disease virus (NDV) challenge of chicks was determined after vaccination with a recombinant herpes virus of turkeys (HVT) expressing the fusion and hemagglutinin-neuraminidase proteins of NDV. One-day-old specific-pathogen-free chicks devoid of maternal antibodies to NDV were vaccinated with 130 to 3300 plaque forming units of HVT (depending on the trial) and then challenged at 4, 7, 10, and 14 days postvaccination (DPV) with a neurotropic velogenic strain of NDV (GB Texas). The recombinant vaccine afforded 0%, 35-75%, 85%, and 94-100% protection when the vaccinated birds were challenged at 4, 7, 10, and 14 DPV, respectively. In all trials, challenge caused 100% mortality in unvaccinated control chicks. Newcastle disease virus was reisolated from the lung, liver, spleen, and brain of birds dying in all trials regardless of vaccine dosage or time of challenge, except when challenge occurred at 14 DPV.

Catastrophic circulatory collapse following re-expansion pulmonary oedema

Re-expansion pulmonary oedema is a recognised but rare complication following the rapid drainage of a large pleural effusion or pneumothorax [1,2], usually occurring on the side of re-inflation. The pathogenesis of the pulmonary oedema is poorly understood but is thought to be due to micro-vascular shearing resulting in neutrophil activation and adhesion to the vascular endothelium resulting in increased micro-vascular permeability [3-7]. Few reports appear in the literature of invasive haemodynamic monitoring following this catastrophe. We describe a patient who sustained fatal pulmonary oedema arising in the contralateral lung, with pulmonary flow catheter data documenting the initial circulatory collapse following the aspiration of a massive pulmonary effusion.

Transforming growth factor alpha and epidermal growth factor levels in bladder cancer and their relationship to epidermal growth factor receptor

We have examined levels of epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha) in neoplastic and non-neoplastic bladder tissue using a standard radioimmunoassay technique. Tumour samples had much higher TGF-alpha levels compared with EGF and TGF-alpha levels in malignant tissue were significantly higher than in benign bladder samples. There was, in addition, a difference in mean EGF levels from 'normal' bladder samples from non-tumour bearing areas of bladder in patients with bladder cancer compared with 'normal' bladder tissue obtained at the time of organ retrieval surgery. Levels of EGF and TGF-alpha did not correlate with levels of EGF receptor (EGFR) as determined by a radioligand binding method but levels of TGF-alpha > 10 ng gm-1 of tumour tissue did correlate with EGFR positivity defined using immunohistochemistry. These data suggest that TGF-alpha is the likely ligand for EGFR in bladder tumours.

Oxidative damage to DNA in diabetes mellitus

BACKGROUND

Increased production of reactive oxygen species (ROS) and lipid peroxidation may contribute to vascular complications in diabetes. to test whether DNA is also oxidatively damaged in diabetes, we measured 8-hydroxydeoxyguanosine (8-OHdG), an indicator of oxidative damage of DNA, in mononuclear cells.

METHODS

For this laboratory-based study, 12 patients with insulin-dependent diabetes mellitus (IDDM) and 15 patients with non-insulin-dependent diabetes mellitus (NIDDM) were matched by age with ten healthy volunteers each. DNA was extracted from mononuclear cells from whole blood. 8-OHdG was assayed by high-pressure liquid chromatography, and ROS were assayed by chemiluminescence.

FINDINGS

IDDM and NIDDM patients had significantly higher median concentrations (p , 0.001, U test) of 8-OHdG in their mononuclear cells than their corresponding controls (in fmol/micrograms DNA): 128.2 (interquartile range 96.0-223.2) and 95.2 (64.0-133.5) vs 28.2 (21.7-43.4) and 21.9 (18.0-24.4), respectively. ROS generation by mononuclear cells was also significantly greater (p < 0.01) in diabetic patients than in their controls (in mV): 238.0 (107.0-243.0) and 101.3 (66.0-134.0) vs 69.5 (49.8-91.9) and 56.0 (38.8-62.5), respectively.

INTERPRETATION

IDDM and NIDDM patients showed greater oxidative damage to DNA, with increased generation of ROS, than controls. Such changes might contribute to accelerated aging and atherogenesis in diabetes and to the microangiopathic complications of the disease.

A genomic map of infectious laryngotracheitis virus and the sequence and organization of genes present in the unique short and flanking regions

We present a genomic map of infectious laryngotracheitis virus (ILT) and an 18,912 bp sequence containing the entire unique short region and a portion of the flanking short repeats. In determining the genomic map, an 856 bp region repeated as many as 13 times was identified within the short repeats. The unique short sequence contains nine potential open reading frames (ORFs). Six of these ORFs show homology to other known herpesvirus unique short genes. Using the herpes simplex virus nomenclature, these genes are the US2, protein kinase, and glycoproteins G, D, I, and E (ORF 1, 2, 4, 6, 7, and 8, respectively). Interestingly, an open reading frame with homology to HSV-1 UL47 (ORF 3) is found in the unique short. One very large open reading frame (ORF 5) is present and contains a threonine-rich, degenerate repeat sequence. This gene appears to be unique to ILT among sequenced herpesviruses. Two ORFs were identified within the short repeat (SR) region. SRORF 1 is homologous to a gene (SORF3) found in the unique short region in both MDV and HVT, and appears to be specific to avian herpesviruses. SRORF 2 has homology to HSV US10.

Employee drug use, demographic characteristics, work reactions, and absenteeism

Employees in a large work organization participated in an investigation of relationships between drug use and absenteeism and tardiness. Specifically, the study investigated the extent to which both self-reported and urine-screened drug use accounted for variance in several types of absenteeism, as well as tardiness, above and beyond that accounted for by demographic and work reaction variables. The results showed that employee drug use accounted for additional statistically significant variance in overall absenteeism and in absenteeism due to injuries and suspensions, as well as days tardy. Implications of these findings for organizational drug testing are discussed.

Psychological and educational support for CAPD patients

Following the development of a small dedicated renal team and the implementation of a new educational and psychological support programme for patients undergoing continuous ambulatory peritoneal dialysis (CAPD), several improvements in outcome measures have become apparent. These changes are also associated with improved patient compliance and overall wellbeing of patients and their families.

Cortisol, progesterone and β-endorphin response to stress in calves

In evaluating stress in farm animals, it would be useful to know whether there were consistent endocrine responses that could be followed. Adrenal cortisol secretion is quite variable, but β-endorphin secretion and adrenal progesterone production may be useful indicators of stress. Changes in plasma concentrations of cortisol, β-endorphin and progesterone were studied in spring-born, castrated male calves (steers) (6 mo of age ± 18 d, 516 ± 26 kg, n = 12) subjected to the stress of routine dehorning. Steers were isolated from their dams for 2 h before headgate restraint (control) or restraint and dehorning. They were bled 60 and 10 min prior to headgate restraint or restraint and dehorning. Blood samples were also collected immediately after headgate restraint or restraint and dehorning (time 0) and 5, 10, 30 and 60 min later. All blood samples were taken from a jugular catheter, and the blood sampling that was done out of the headgate involved minimal manual restraint. Plasma β-endorphin concentrations were similar in control steers and dehorned steers (P > 0.05) and decreased significantly following restraint or restraint and dehorning (P < 0.05). Plasma cortisol concentrations rose significantly 5 min after dehorning and were elevated for 60 min; but with restraint only, plasma cortisol concentrations rose to a peak 5 min after release from chute restraint and then declined (P < 0.05). Plasma cortisol concentrations were greater in dehorned steers than in control steers in the period from 10 min after dehorning or headgate restraint to 60 min after headgate restraint (P < 0.0043). Plasma progesterone concentrations rose to a peak 10 min after dehorning and then declined, but in control steers, a peak was seen at 5 min after release from restraint (P < 0.05). Plasma progesterone concentrations were greater in dehorned steers between 5 and 60 min after dehorning than in control steers (P < 0.05). From these data, we concluded that in prepubertal, castrated male calves, β-endorphin was not released in any significant quantities in response to the stress of dehorning. In steers, adrenal cortisol and progesterone were secreted in response to acute stress, and a ratio of the two may provide a useful assessment of stress; this requires further study. Key words: Cortisol, progesterone, β-endorphin, stress, calves

Detection of herpes simplex and varicella-zoster infection from cutaneous lesions in different clinical stages with the polymerase chain reaction

BACKGROUND

The polymerase chain reaction (PCR) can be used to diagnose a variety of infectious processes.

OBJECTIVE

We sought to determine whether Tzanck smear debris, vesicle fluid swabs, crusts, or fixed tissue specimens are the best source for template herpes simplex virus (HSV) or varicella-zoster virus (VZV) DNA for the PCR.

METHODS

Patients with both clinical and histologic evidence of HSV (n = 6) or VZV (n = 16) infection were examined. Stained Tzanck smears, vesicle fluid swabs, dried crusts, and skin biopsy specimens were obtained at the same time from each patient. DNA was extracted from the different clinical specimens and then examined for HSV or VZV DNA with PCR. Fifteen control subjects did not have clinical or histologic evidence of herpesvirus infection.

RESULTS

In cases of suspected VZV infection, PCR detected VZV DNA sequences from all 15 Tzanck smears, all 15 vesicle swabs, one of one crust, and 14 of 16 fixed tissue specimens. HSV DNA sequences were detected from all six Tzanck smears, all four vesicle fluid swabs, two of two crusts, and five of six fixed tissue specimens.

CONCLUSION

PCR can detect VZV and HSV DNA sequences from a variety of sources including formalin-fixed tissue specimens. Although viral DNA was detected slightly more frequently from Tzanck smear debris, crusts, and vesicle fluid swabs compared with fixed tissue specimens, each was an excellent source of target DNA for the PCR to confirm the diagnosis of herpesvirus infection.

Use of the biotinylated antibody DAKO-ER 1D5 to measure oestrogen receptor on cytokeratin positive cells obtained from primary breast cancer cells

A method for the use of a biotinylated antibody (DAKO-ER 1D5) to quantify oestrogen receptors (ER) on tumour cells by flow cytometry is described. ER quantification was determined after treatment with saponin rendering cells permeable to ER antibody. Use of dual parameter labelling was performed utilizing a FITC-conjugated antibody (NCL-5D3) directed against cytokeratin 8/18. This allowed selection of breast cancer cells of epithelial origin by gating to exclude contaminating inflammatory and stromal cells. Use of such a gating technique was seen to identify cells with a higher level of ER expression. Using QC quantum bead standards, the number of ER binding sites per cell was assessed. Results were compared with conventional ER quantification using a radio-ligand binding assay. A high degree of correlation was found between the two methods. The flow cytometric method for ER quantification described is simple, rapid, and reproducible. The assay may be of particular value in measuring ER on urgent clinical samples. Advantages of this assay over the radio-ligand binding assay include reduction in use of radio-labelled iodine compounds, a decrease in analysis time, and reduced cost and quantity of material needed for assay.

Molecular phylogeny and evolutionary timescale for the family of mammalian herpesviruses

A detailed phylogenetic analysis for mammalian members of the family Herpesviridae, based on molecular sequences is reported. Sets of encoded amino acid sequences were collected for eight well conserved genes that are common to mammalian herpesviruses. Phylogenetic trees were inferred from alignments of these sequence sets using both maximum parsimony and distance methods, and evaluated by bootstrap analysis. In all cases the three recognised subfamilies (Alpha-, Beta- and Gammaherpesvirinae), and major sublineages in each subfamily, were clearly distinguished, but within sublineages some finer details of branching were incompletely resolved. Multiple-gene sets were assembled to give a broadly based tree. The root position of the tree was estimated by assuming a constant molecular clock and also by analysis of one herpesviral gene set (that encoding uracil-DNA glycosylase) using cellular homologues as outgroups. Both procedures placed the root between the Alphaherpesvirinae and the other two subfamilies. Substitution rates were calculated for the combined gene sets based on a previous estimate for alphaherpesviral UL27 genes, where the time base had been obtained according to the hypothesis of cospeciation of virus and host lineages. Assuming a constant molecular clock, it was then estimated that the three subfamilies arose approximately 180 to 220 million years ago, that major sublineages within subfamilies were probably generated before the mammalian radiation of 80 to 60 million years ago, and that speciations within sublineages took place in the last 80 million years, probably with a major component of cospeciation with host lineages.

The use of a laryngotracheal separation procedure in pediatric patients

The objective of this study was to review experience, outcome, and satisfaction after a laryngotracheal separation (LTS) procedure in pediatric patients. Chart reviews and phone questionnaires were used. Factors reviewed included hospitalizations and infections prior to and after LTS, morbidity, and impact on quality of life. Twenty-one pediatric patients ranging in age from 8 to 172 months underwent LTS. Follow-up time ranged from 1 to 49 months. Complications were minor. Eighty-eight percent of patients had fewer hospitalizations or were discharged for the first time after LTS. Number of pneumonias and suctioning frequency decreased, mobility increased in patients with prior tracheostomies, and care requirements decreased in 95% of patients. Parents reported satisfaction and improved quality of life. LTS is a low-risk, successful procedure which increases quality of life and decreases morbidity in pediatric patients with irreversible upper airway dysfunction.

Stages leading to and following fusion of sperm and egg plasma membranes

The site of gamete interaction of electrophysiologically recorded Lytechinus variegatus eggs, fixed with osmium tetroxide (OsO4) and/or glutaraldehyde (GTA) at varying intervals after the onset of the increase in membrane conductance induced by an attached sperm, has been examined by high-voltage and conventional transmission electron microscopy. Although GTA and a GTA-OsO4 mixture induced different electrical responses, specimens prepared with the two fixatives were ultrastructurally similar. In specimens observed within 5 s of the change in conductance, the acrosomal process projected through the vitelline layer and abutted the egg plasma membrane. A conspicuous layer of bindin surrounded the acrosomal process and connected the sperm to the egg's vitelline layer. In a fortuitous specimen fixed within 4 s following the change in conductance, the area of contact between the gamete plasma membranes possessed a trilaminar structure that separated the egg's and sperm's cytoplasms. The morphology of this area of contact was consistent with previously proposed intermediates of membrane fusion. Five to six seconds after the change in conductance, the sperm was connected to the egg via a narrow cytoplasmic bridge that consisted of the former acrosomal process and a projection of the egg cortex. The region of the bridge midway between the fused gametes was encircled by dense material that marked the site of sperm-egg fusion. Gamete interactions in which the activation potential was recorded (unclamped egg) were comparable in time and ultrastructure to events taking place in voltage-clamped eggs except for one major difference. Intact cortical granules (one to three) were observed beneath the tip of the incorporating sperm in unclamped eggs fixed following the onset of the activation potential, whereas all cortical granules dehisced in clamped eggs.

Defective measles virus in human subacute sclerosing panencephalitis brain

Evidence is presented showing that the brain cells of patients with subacute sclerosing panencephalitis (SSPE) contain mutant measles (MV) genomes having the characteristics of 5' copy-back defective interfering (DI) RNAs. Using a polymerase chain reaction-based amplification specific for copy-back DIs, abundant, discrete cDNAs representing different-sized MV defective RNA species were generated from each SSPE brain. The defective genomes were cloned in two portions. The most common of these defective species were sequenced, confirming their MV genome origin and 5' copy-back nature. We deduced that the minimum DI stem length of these species was 95 nucleotides, further delimiting the prerequisite 5' regulatory region sequences specifying MV genomic replication/encapsidation functions. This calculation assumes a precise copy-back mechanism and complete complementarity of the panhandle structure. Since the SSPE-derived viral genome encodes dysfunctional viral envelope proteins, we hypothesize that SSPE brains may lack the high degree of selective pressure encountered in tissue culture MV infections. This allows for the coexistence of numerous replication-competent defective particles in each SSPE brain. A role for viral defective particles as modulators of this persistent measles virus infection of humans is proposed.