Stimulation of 5-HT2A receptors on astrocytes in primary culture opens voltage-independent Ca2+ channels

A two-step exocytosis/endocytosis protocol was used in rat pancreatic acini to study membrane trafficking events at the apical plasma membrane (APM) as a function of extracellular pH. Exocytosis, as measured by cholecystokinin (CCK)-8-induced release of amylase into the incubation medium, was relatively insensitive to changes in extracellular pH from 5.5 to 9.0. In contrast, endocytosis, as measured by temperature-dependent uptake of horseradish peroxidase (HRP), was robust at pH values between 6.5 and 8.3 but abolished at acidic pH values of 5.5 to 6.0. Energy metabolism and cell viability were maintained during pH 6-induced cessation of HRP uptake, and the vesicular block could be reversed upon raising the luminal pH to 7.4. Histochemical and morphometric studies of HRP uptake examined by electron microscopy indicated that extracellular pH regulates endocytosis at the apical plasma membrane. At pH 6.0 in prestimulated cells, HRP uptake at the APM was abolished, and acinar lumen membranes remained markedly dilated with decreased density of microvilli and "arrested" exocytic images. At pH 7.4, HRP was taken up into endolysosomal structures within the Golgi complex, and acinar lumen membranes were contracted. Cleavage of GP2, a glycosyl phosphatidylinositol-anchored protein, was associated with the pH-dependent activation of HRP uptake. These studies demonstrate that acinar lumen pH regulates endocytic but not exocytic activity at the APM and suggest that alkalinization of the acinar lumen by duct cells is required for retrieval of exocytic membranes into the acinar cell via vesicular uptake mechanisms. The role of acid-base interactions within the acinar lumen provides a novel basis for understanding the cellular and luminal defects observed within the exocrine pancreas in cystic fibrosis.     

Three-dimensional analysis of contrast-filled microvessel diameters

Organ blood flow is controlled, in part, by changes in diameter of resistance vessels. In thick tissue, vessels can be imaged with a microscope using contrast-enhancing methods (e.g., fluorescence) and image analysis techniques can be used for quantitative diameter estimations. However, a change in the position of a vessel with respect to the plane of focus can be misinterpreted as a diameter change. In order to address this problem, a 3D image in a light microscope is obtained by serial optical sectioning, and a 3D deconvolution procedure (Avinash et al., 1991, "Fourteenth Association for Research in Otolaryngology Midwinter Meeting, St. Petersberg, FL," Abstract 156) is used to deblur 3D image data. Deblurred sections are computationally projected onto a 2D plane to give an extended-focus image, from which diameter estimates of microvessels are made using a quantitative, 2D diameter-tracking algorithm (Miles, 1987, "Semiautomatic Quantitative Image Analysis of Dynamic in Vivo Cochlear Microvessel Diameters." Ph.D. dissertation, Univ. Michigan; Miles and Nuttall, 1992, IEEE Trans. Biomed. Eng.). Justification for 3D preprocessing before diameter analysis is provided by absolute and relative error analyses using computer-generated synthetic vessels. The 3D diameter analysis technique is validated using a capillary tube of known diameter, filled with fluorescent solution. Demonstration of its applicability is shown in diameter measurements from the vessels of guinea pig cochlea. Our approach, using extended-focus images, minimizes overestimation of microvascular diameters and underestimation of relative diameter changes. Therefore, unambiguous diameter measurements are possible with extended-focus images.     

Detecting and discriminating the direction of motion of luminance and colour gratings

Human observers were required to discriminate the direction of motion of vertically moving, 1 c/deg luminance and colour gratings. The gratings had different contrasts and moved at temporal frequencies between 0.5 and 32 Hz. Sensitivity [the reciprocal of the contrast at which performance reached 75% correct in a temporal two-alternative forced-choice (2 AFC) discrimination task] was a band-pass function of temporal frequency for luminance gratings, and a low-pass function of temporal frequency for colour gratings. Further, when colour contrast was expressed in terms of the modulation in cone excitation produced by the stimulus, sensitivity to colour gratings was greater than sensitivity to luminance gratings at frequencies below 2 Hz. On the other hand, at temporal frequencies above 4 Hz, sensitivity to colour gratings was comparable with sensitivity to luminance gratings of double the temporal frequency. Detection sensitivity was measured for luminance and colour gratings of 1, 4 and 16 Hz. With either colour or luminance gratings, detection thresholds were very similar to those for direction-of-motion discrimination. This result confirms findings of Mullen and Boulton [(1992) Vision Research, 32, 483-488] and Cavanagh and Anstis [(1991) Vision Research, 31, 2109-2148], but is different from that reported by Lindsey and Teller [(1990) Vision Research, 30, 1751-1761] who used a smaller stimulus seen in a parafoveal region and found that motion discrimination thresholds were higher than detection threshold for colour gratings. We repeated our threshold measurements using parafoveal viewing conditions similar to those used by Lindsey and Teller (1990). We found that, although for luminance gratings detection thresholds were very close to direction-discrimination thresholds, for colour gratings, they were lower. The result is in qualitative agreement with Lindsey and Teller (1990). Our results suggest that low-level, or "first-order" motion mechanisms are not as sensitive to chromatic gratings as are colour-detection mechanisms.     

Systemic lupus erythematosus in children: the complex problems of diagnosis and treatment encountered in 101 such patients at the Mayo Clinic

Between 1945 and 1970, 101 children (86 girls and 15 boys) with systemic lupus erythematosus were evaluated at the Mayo Clinic. Only 9 children were less than 9 years old at the time of diagnosis. The most frequent presenting complaint was arthralgia; fever, fatigue, and a "butterfly" malar rash also were common. Renal involvement, found in more than 76 per cent of patients, was a prognostically poor sign. The overall survival of children with renal involvement is improved by the use of adequate steroid therapy.     

Unilateral total lobectomy: is it sufficient surgical treatment for patients with AMES low-risk papillary thyroid carcinoma?

BACKGROUND: Controversy continues regarding the optimal extent of primary thyroid resection in most patients with papillary thyroid carcinoma (PTC), who are at minimal risk of cause-specific mortality (CSM). This study was designed to compare CSM and recurrence rates after either unilateral lobectomy (UL) or bilateral lobar resection (BLR) in patients with PTC considered low risk by AMES criteria. METHODS: Outcome was studied in 1685 patients initially treated during 1940 through 1991 and followed for up to 54 postoperative years (mean, 18 years). One thousand six hundred fifty-six patients (98%) had complete primary tumor resection; 634 (38%) had involvement of regional nodes. One hundred ninety-five patients (12%) had UL; BLR accounted for 1468 (near-total 60%; total thyroidectomy 18%). RESULTS: Thirty-year rates for CSM and distant metastasis were 2% and 3%, respectively. Twenty-year rates for local recurrence and nodal metastasis were 4% and 8%, respectively. There were no significant differences in CSM or distant metastasis rates between UL and BLR (P > .2). After UL, 20-year rates for local recurrence and nodal metastasis were 14% and 19%, significantly higher (P = .0001) than the 2% and 6% rates seen after BLR. CONCLUSIONS: UL was not associated with higher CSM rates, but it was associated with a significantly higher risk of locoregional recurrence. Thus BLR probably represents a preferable initial surgical approach to patients with low-risk PTC.     

The cortisol response to psychological stress in temporomandibular dysfunction

Recombinant antibody fragments can be produced in large quantities using bacterial expression systems and could potentially be useful for the generation of biofilters for the selective removal of viral particles from fluids. A human single chain-Fv antibody library, derived from synthetic repertoires of germ line VH-gene segments rearranged in vitro and paired to a single light chain (Nissim et al., 1994, EMBO J., 13, 692-698), has recently been used to isolate hundreds of different binding specificities by panning with antigen. Antibodies from this library typically have affinities in the 10(6)-10(7) M-1 range. Occasionally, better binders are isolated but at other times the affinities recovered are poor. In the latter situation binding cannot be detected with soluble antibodies, but only by high-avidity display of multiple copies of antibodies on phage. By panning with human cytomegalovirus (HCMV)-coated immunotubes, we have isolated a number of antibody clones from this library that bound to the antigen only if displayed on the filamentous phage, but not in soluble form. One of these clones was selected for an affinity maturation procedure, achieved by combinatorial mutagenesis of the complementarity determining region 3 (CDR3) of the antibody light chain, followed by selection of the resulting library for HCMV binding. By this means, we were able to isolate a number of binders, some of which exhibited specific HCMV binding in soluble form. The clone that gave the strongest ELISA signal was expressed in bacteria, purified in solution, characterised using a novel capture methodology with surface plasmon resonance detection on a BIAcore instrument and used for the production of an immunofilter for the removal of HCMV form human serum. The filter removed more than 99% of applied HCMV in 10 min circulation time, while the amount of HCMV retained non-specifically in a cartridge derivatised with a non-specific antibody was less than 10% under similar conditions.     

Stenting of "unprotected" left main coronary artery stenoses: early and late results

The effect of bone plug length and Kurosaka screw (DePuy, Warsaw, IN) diameter on graft holding strength of the bone-tendon-bone construct was determined. Random length porcine bone plugs were assigned to fixation with 7 or 9 mm Kurosaka screws. Peak load to failure was determined. There was a significant decrease in peak load to failure of the 5-mm long bone plugs compared with longer bone plugs. No difference was found between longer lengths of bone plug in either the 7- or 9-mm screw diameter groups. The 9-mm diameter screws significantly increased peak load to failure for both 1- and 2-cm bone plug lengths.     

Reporting risks and benefits of therapy by use of the concepts of unqualified success and unmitigated failure: applications to highly cited trials in cardiovascular medicine

BACKGROUND: The NNT (number needed to treat) and NNH (number needed to harm) are useful in conveying the results of clinical trials because they emphasize the effort that must be expended to accomplish a single, tangible outcome. But NNT conveys the effort required to achieve a positive outcome without distinguishing between the presence or absence of treatment-related adverse events. Similarly, NNH conveys harm without accounting for the achievement or lack of achievement of the benefit of therapy. Consequently, a mathematical model was developed to extend the NNT and NNH to represent the effort required to achieve "unqualified success" (NNTUS, treatment success without treatment-induced side effects) and "unmitigated failure" (NNHUF, lack of treatment success with treatment-induced side effects). METHODS AND RESULTS: NNTUS was calculated by adjusting the absolute risk reduction to allow for the probability of not incurring a treatment-related adverse event. NNHUF was similarly calculated by adjusting the absolute risk of incurring a treatment-related adverse event by the probability of not incurring any treatment-related benefit. The impact of conveying clinical trial data by the use of NNT, NNTUS, NNH, and NNHUF is illustrated by means of 11 highly cited trials identified systematically from the cardiovascular literature. The treatment effort measured by the NNTUS and the NNHUF was consistently higher than that given by the traditional NNT and NNH. These increments ranged from 1% to several hundred percent. CONCLUSIONS: The NNTUS and the NNHUF represent the treatment effort required on average to achieve 1 unqualified success and 1 unmitigated failure. NNTUS and NNHUF balance benefit and harm in an objective way and are relevant for making service delivery decisions.     

Phosphatidylinositol 3-kinase is required for CD28 but not CD3 regulation of the TEC family tyrosine kinase EMT/ITK/TSK: functional and physical interaction of EMT with phosphatidylinositol 3-kinase

Ligation of the TCR or CD28 induces activation of phosphatidylinositol 3-kinase (PI3K), the TEC family protein tyrosine kinase, EMT/ITK/TSK (EMT), and the SRC family tyrosine kinase, LCK. LCK is required for the activation and phosphorylation of EMT induced by ligation of the TCR or CD28 placing LCK upstream of EMT in T cell signaling cascades. We report herein that inhibition of PI3K activity with the specific inhibitors LY294002 and wortmannin markedly decreased EMT activation induced by CD28 cross-linking but not by CD3 cross-linking. Further, inhibition of PI3K markedly decreased EMT in vitro autokinase activity induced by activated LCK. In contrast, PI3K inhibitors did not alter CD28 or CD3 cross-linking or LCK-induced EMT phosphorylation. Consistent with the requirement of PI3K activity for CD28 but not CD3-induced stimulation of the EMT in vitro autokinase activity, a small but significant portion of cellular EMT associates with PI3K following CD28 cross-linking but not following CD3 cross-linking. CD28-induced association of EMT with PI3K also requires functional expression of LCK. Fusion proteins containing the SRC homology 2 domain of EMT interact with PI3K or a PI3K-associated molecule in a tyrosine phosphorylation-dependent manner. Taken together, the data suggest that EMT is differentially regulated and recruited to different signaling complexes following ligation of CD28 or the TCR complex, perhaps contributing to the disparate roles that EMT appears to play downstream of CD28 and the TCR.     

The envelope glycoprotein ectodomains determine the efficiency of CD4+ T lymphocyte depletion in simian-human immunodeficiency virus-infected macaques

CD4+ T lymphocyte depletion in human immunodeficiency virus type 1 (HIV-1)-infected humans underlies the development of acquired immune deficiency syndrome. Using a model in which rhesus macaques were infected with chimeric simian-human immunodeficiency viruses (SHIVs), we show that both the level of viremia and the structure of the HIV-1 envelope glycoprotein ectodomains individually contributed to the efficiency with which CD4(+) T lymphocytes were depleted. The envelope glycoproteins of recombinant SHIVs that efficiently caused loss of CD4(+) T lymphocytes exhibited increased chemokine receptor binding and membrane-fusing capacity compared with those of less pathogenic viruses. These studies identify the HIV-1 envelope glycoprotein ectodomains as determinants of CD4(+) T lymphocyte loss in vivo and provide a foundation for studying pathogenic mechanisms.