[Halogen-induced panniculitis caused by potassium bromide]

Necrotizing panniculitis due to potassium-bromide is a drug induced allergic reaction following stimulation of lymphocytes as demonstrated for the first time by a lymphocyte transformation test (LTT). We named the disease "halogen panniculitis" because of similar generally known reactions to iodides and describe the typical symptoms in three own cases. Bromoderma tuberosum tends to be a similar kind of allergy. For the first time pancreatitis to potassium bromide in men has been observed, which has already been described in epileptic dogs treated with potassium bromide.

Classification and severity of postdural puncture headache. Comparison of 26-gauge and 27-gauge Quincke needle for spinal anaesthesia in day-care surgery in patients under 45 years

Two hundred and five patients, aged 16-45 years, undergoing day care surgery were given a spinal anaesthetic using either a 26- or a 27-gauge Quincke point spinal needle. The occurrence of headache and accompanying symptoms postoperatively was analysed from 186 returned questionnaires. The incidence of classical postdural puncture headache was 4.5% following the use of a 26-gauge needle and 8% with a 27-gauge needle (p > 0.05). A further group of patients suffering headache after dural puncture was identified, the postdural puncture-related headache. The headache and accompanying symptoms were similar to that seen with a postdural puncture headache except that it was not aggravated by posture. A system of grading the severity of both type of headache is presented and standardised criteria for the classification of postdural puncture headache are proposed.

Ocular artifacts in EEG and event-related potentials. I: Scalp topography

The ocular artifacts that contaminate the EEG derive from the potential difference between the cornea and the fundus of the eye. This corneofundal or corneoretinal potential can be considered as an equivalent dipole with its positive pole directed toward the cornea. The cornea shows a steady DC potential of approximately +13 mV relative to the forehead. Blink potentials are caused by the eyelids sliding down over the positively charged cornea. The artifacts from eye-movements result from changes in orientation of the corneo-fundal potential. The scalp-distribution of the ocular artifacts can be described in terms of propagation factors--the fraction of the EOG signal at periocular electrodes that is recorded at a particular scalp location. These factors vary with the location of the scalp electrode. Propagation factors for blinks and upward eye-movements are significantly different.

Ocular artifacts in recording EEGs and event-related potentials. II: Source dipoles and source components

The source dipoles for blinks point radially whereas the source dipoles for saccades point tangentially, in the direction of the eye movement. This indicates that blink potentials are not generated by eye movements but by the eyelid sliding down over the positively charged cornea. Dipole source dipole analysis shows that the "rider artifact" at the onset of upward and lateral saccades is caused by the eyelid as it lags a little behind the eyes at the beginning of the movement. Dipole source analysis allows both the EEG and the EOG to be modeled simultaneously and EOG generators to be distinguished from nearby EEG generators. Ocular source components can be calculated from a principal component analysis of EEG and EOG recordings during blinks and saccades. The effectiveness of propagation factors, source dipoles and source components in removing ocular artifacts from EEG samples was assessed. The most effective correction procedure uses source components.

A mammalian protein complex that repairs double-strand breaks and deletions by recombination

We have purified a high molecular weight complex (RC-1) from calf thymus nuclei that catalyzes a recombinational repair of double-strand gaps and deletions in DNA by gene conversion as well as cross-over events leading to cointegrant products. These have been detected by polymerase chain reaction analysis using oligonucleotide primer pairs that detect joined sequences originally present on only one or the other of the recombination substrates. RC-1 has an apparent molecular mass of about 550-600 kDa and contains at least five polypeptide chains: molecular masses about 230, 210, 160, 130, and 40 kDa. RC-1 contains a DNA polymerase, identified as DNA polymerase epsilon, that co-purifies with RC-1. A DNA ligase, most likely mammalian DNA ligase III, and a 5'-3' exonuclease also copurify with the RC-1. Most preparations of RC-1 contain low levels of a double-strand endonuclease, 3'-5' exonuclease and single-strand nuclease activities. However, DNA helicase, terminal deoxynucleotidyl transferase, or DNA topoisomerase I and II were not detected in RC-1. The DNA polymerase and DNA ligase in RC-1 can act in concert to repair a multiply gapped DNA to a covalently repaired duplex. The bovine single-strand-binding protein stimulates the formation of the recombination products and the repair reaction mentioned above about 4-fold.

Diffuse vascular ectasia of the antrum, duodenum, and jejunum in a patient with nodular regenerative hyperplasia. Lack of response to portosystemic shunt or gastrectomy

The case is reported of a 70 year old man who presented with severe anaemia because of chronic gastrointestinal blood loss. This loss was ascribed to vascular ectasia resembling the gastric antral vascular ectasia syndrome but extended to include the antrum, the duodenum, the jejunum, and, possibly, the cardiac area. This condition was associated with portal hypertension as a result of nodular regenerative hyperplasia. Consecutive treatments including sucralfate, prostaglandin E2, propranolol, organic nitrates, pentoxyphilline, corticosteroids, endoscopic sclerotherapy, portosystemic shunt, total gastrectomy, proved ineffective.

Physical aspects of the EEG in schizophrenics

Physical and dynamic aspects of the electroencephalogram (EEG) were evaluated in 12 schizophrenic patients and 12 matched healthy control subjects by means of two descriptive measures proposed by Hjorth (complexity and mobility) and by a nonlinear measure, dimensional complexity. These measures were compared to power spectra analyses. EEG was recorded from frontal, central, and parietal leads under resting conditions (eyes open and eyes closed) for 12 epochs each of 25 sec. Patients showed the expected increased activity in the 1-7 Hz band and, furthermore, a scalp distribution of dimensional complexity and Hjorth complexity opposite to the distribution in controls: in patients dimensional complexity yielded higher values at frontal (Fz) than central (Cz) leads, whereas the resemblance to sinusoidal waveshape (Hjorth complexity) was larger at Fz than Cz. Results indicate more dynamic complexity or variables determining the dynamics of brain processes in frontal areas in patients.

Eyeblinks evoke potentials in the occipital brain region

The subjects performed voluntary eyeblinks under illuminated and dark laboratory conditions. 32-channel EEG recordings were averaged in relation to the eyeblinks and a brain electric source analysis (BESA) was performed. Two dipoles located near the eyeballs and a third dipole in the occipital region of the brain were found to explain the scalp potentials. The frontally located potentials described electromechanical potentials associated with lid movements and simultaneous eye movements. The occipitally located dipole explained a visually evoked potential with a first peak at about 180 ms after the maximum of the frontal blink potential. The visually evoked potential was observed only under illumination and was probably caused by changes in luminance during the eyeblinks.

Rapid assembly and disassembly of complementary DNA strands through an equilibrium intermediate state mediated by A1 hnRNP protein

A1 hnRNP protein, which rapidly renatures complementary strands of nucleic acids in vitro, affects both the equilibrium and kinetic properties of the reaction (single-stranded DNA in equilibrium with double-stranded DNA). A1 lowers the melting transition of duplex DNA. However, at temperatures above this new Tm, both single- and double-stranded DNAs are present at equilibrium and are rapidly interconverting. Although the ratio of single and double strands under these conditions is a function of both the A1 protein and complementary DNA strand concentrations, it is not strongly affected by further increases in temperature. These surprising results demonstrate that A1 does not act as a simple catalyst in promoting renaturation and indicate how A1 and other proteins could act to speed the turnover of intermediate complexes in important biological processes.

Homologous recombination of copackaged retrovirus RNAs during reverse transcription

According to prevailing models, the high frequency of recombination in retroviruses occurs during reverse transcription of two genetically different genomes copackaged into virion particles. This view has been tested in our studies of the mechanism of recombination within homologous sequences of two retroviral genomes during a single round of virus replication and in the absence of helper virus. The recombination substrates were Moloney murine leukemia virus-based vectors, each of which contains an altered defective neomycin gene (neo) under the transcriptional control of the 5' long terminal repeat; the 3' sequences of each construct contain either the Moloney murine leukemia virus or simian virus 40 large-T polyadenylation sequence. One neo gene contained a linker insertion mutation at the 5' end (neo minus), and the other contained a deletion and linker insertion at the 3' end (neo delta 3). Each of the mutant neo constructs was introduced into the packaging helper cell line psi 2 by sequential cotransfection, and individual psi 2 double transformants were selected. Supernatant fluids from the cloned psi 2 double transformants were used to infect NIH 3T3 cells, and recombinant neo+ proviruses were detected by their ability to confer G418 resistance during infection of NIH 3T3 cells. Our results show that (i) recombination between a homologous sequence of about 560 bp occurred with a frequency of about 10(-4) per virus replication cycle; (ii) recombination occurred only after the viral RNAs had been packaged into particles, i.e., recombination between the two vector DNAs or between viral RNAs prior to packaging was not detected; and (iii) copackaging of two different genomic RNAs as a heterodimer is a prerequisite for recombination. Furthermore, our results indicate that recombination can occur during the DNA negative-strand synthesis of reverse transcription.

Methylene dianiline: assessment of exposure and cancer morbidity in power generator workers

The biaromatic amine 4,4'-methylene dianiline (MDA) is an animal carcinogen, possibly also carcinogenic to humans. In a cohort of 595 power generator workers potentially exposed to MDA in a curing agent of an epoxy system, the overall standardised cancer incidence ratio (SIR) among males (n = 550), however, was only 0.52 [95% confidence interval (CI) 0.16-1.21] based on five observed cases. One male urinary bladder cancer case was found in comparison to 0.6 expected (SIR 1.67; 95% CI 0.04-9.31). This case was identified in an unexposed subcohort. High levels of MDA metabolites were ascertained in the urine of currently exposed workers, probably following percutaneous absorption. Although no evidence of an increased overall or bladder cancer risk was detected, the limitations of the study in regard to the size of the cohort, age and cancer latency preclude a definite risk assessment. The dermal absorption of MDA has been highlighted.

Rapid renaturation of complementary DNA strands mediated by cationic detergents: a role for high-probability binding domains in enhancing the kinetics of molecular assembly processes

The rate of renaturation for complementary DNA strands can be enhanced greater than 10(4)-fold by the addition of simple cationic detergents, and the reaction is qualitatively and quantitatively very similar to that found with purified heterogeneous nuclear ribonucleoprotein A1 protein. Under optimal conditions, renaturation rates are greater than 2000-fold faster than reactions run in 1 M NaCl at 68 degrees C. The reaction is second-order with respect to DNA concentration, and reaction rates approach or equal the rate with which complementary strands are expected to encounter each other in solution. Renaturation can even be observed well above the expected melting temperature of the duplex DNA, demonstrating that some cationic detergents have DNA double-helix-stabilizing properties. The reaction is also extremely rapid in the presence of up to a 10(6)-fold excess of noncomplementary sequences, establishing that renaturation is specific and relatively independent of heterologous DNA. This finding also implies that up to several thousand potential target sequences can be sampled per strand per second. Such reagents may be useful for procedures that require rapid nucleic acid renaturation, and these results suggest ways to identify and design other compounds that increase the kinetics of association reactions. Moreover, this work provides further support for a model relating the existence of flexible, weakly interacting, repeating domains to their function in rapid molecular assembly processes in vitro and in vivo.

Transurethral balloon dilatation of the prostatic urethra: effectiveness in highly selected patients with prostatism

Transurethral balloon dilatation of the prostate has been shown to be a safe and potentially effective alternative to surgery in the treatment of benign prostatic hyperplasia, with a 66% success rate in relatively unselected patients. This study hypothesized that more careful patient selection might result in a significantly better rate of improvement. Ninety-one subjects with symptoms and signs of prostatism attributable to benign prostatic hyperplasia were studied. Group 1 comprised 42 patients with an initial mean symptom score of 16.8, residual urine of 249 ml, maximal flow rate of 7.9 ml/sec, and nomogram of maximal flow rate of -1.5. Group 2 comprised 49 less symptomatic patients with an initial mean symptom score of 14.5, residual urine of 105 ml, maximal flow rate of 10.7 ml/sec, and nomogram of maximal flow rate of -0.8. The difference in mean age and prostate size between groups was not statistically significant, but differences in baseline symptom score, residual urine, maximal flow rate, and nomogram of maximal flow rate were significant (p less than .04). Transurethral balloon dilatation of the prostate was performed under local anesthesia or IV sedation and analgesia with single-or double-balloon catheters with maximal diameters of 25-30 mm inflated to 2.5-4.0 atmospheres pressure for 10 min. Patients were followed up with repeat symptom scoring, uroflometry, and measurement of residual urine. After a mean follow-up of 22 months (range, 6-48 months), an improvement in symptom score was seen in 80% of group 2 patients compared with 43% in group 1. Improvement in symptom scores was statistically significant in both groups (p less than .04). We conclude that transurethral balloon dilatation of the prostate is more effective in patients with more moderate symptoms and with less marked signs of obstruction than in patients with more marked prostatism.

Dipole models of eye movements and blinks

Average EOGs were recorded from 4 subjects for vertical and horizontal eye movements of 15 degrees away from and back to a central fixation point, and for eyeblinks while looking at the fixation point. Using spatio-temporal dipole modelling, several alternative dipole models of the electrical activity of the eyes were compared. A reasonable fit was only obtained if the equivalent dipoles were allowed to take up different locations and orientations depending on the type of eye activity. It appears that (a) the equivalent ocular dipole is located away from the axis of rotation of the eyeball, (b) eyelid movements contribute to a change in location of the dipole in vertical eye movements and blinks, and (c) some of the apparent dipole movement is due to inadequacy of the 3-shell spherical head model near to the eyes. Consequences of the results for eye-artifact correction are discussed.

The waltzing oddball

We investigated whether task relevance and probability interact to influence P3 amplitude. High and low tones were presented in random order with equal probability. In the control condition (standard oddball), every high tone had to be counted. In the waltz condition, high tones had to be counted only if they were preceded by two other high tones. It was predicted that the P3s evoked by targets in the waltz condition would be larger than the P3s evoked by the same sequence of targets in the oddball condition. That is, the frequency of occurrence of the targets should have an effect on P3, in addition to effects of the frequency of stimulus occurrence and stimulus task relevance (target/nontarget). This prediction was upheld. However, the largest P3s were evoked by nontargets following two high tones in the waltz condition. These P3s had a more anterior topographic maximum than usual. We contend that these anterior P3s reflect the interruption of an ongoing task and cannot be easily fit into the framework of the two concepts of task relevance and probability.

Expression of the type 1 human immunodeficiency virus Nef protein in T cells prevents antigen receptor-mediated induction of interleukin 2 mRNA

Stable transformants of the Jurkat T-cell line have been obtained that express either of two distinct forms of the type 1 human immunodeficiency virus nef gene: the nef-1-encoded protein (Nef-1) contains alanine, glycine, and valine at positions 15, 29, and 33, respectively; the protein specified by nef-2 (Nef-2) has threonine, arginine, and alanine at the corresponding positions. When Jurkat cells or their Nef-2-expressing transformants are treated with phorbol 12-myristate 13-acetate (PMA) plus either phytohemagglutinin (PHA) or antibodies against CD3 epsilon, T-cell receptor beta chain, or CD2, there is a prompt increase in interleukin 2 (IL-2) mRNA and intracellular calcium and in the IL-2 receptor alpha chain on the cell surface. Although cells expressing Nef-1 also induce calcium mobilization and the production of IL-2 receptor alpha chain, the formation of IL-2 mRNA is blocked in response to these stimuli. Moreover, Nef-1-expressing cells transfected with a plasmid in which the IL-2 promoter is fused to the chloramphenicol acetyltransferase (CAT) gene fail to induce CAT following treatment with PMA and PHA. By contrast, the parental and Nef-2-containing cells induce CAT normally. Nef-1-expressing cells can produce IL-2 mRNA in response to a combination of PMA and ionomycin, although much less efficiently than the parental Jurkat cells or Nef-2-expressing cells. These findings, and others described herein, suggest that the virally encoded Nef protein interferes with a signal emanating from the T-cell receptor complex that induces IL-2 gene transcription.

A lateral skin incision reduces peripatellar dysaesthesia after knee surgery

In a series of 64 ligamentous injuries of the knee, 33 were explored through a medial incision and 31 through a long lateral incision. Sensibility of the skin, the occurrence of neuromas, and discomfort during kneeling were evaluated three and six years postoperatively. The lateral incisions produced less dysaesthesia, fewer neuromas and less discomfort on kneeling.

[Significance of autoimmunity in various forms of uveitis]

Autoimmune diseases are the result of a false recognition by the immune system of the own tissue as foreign. Suppressor cells serve to inhibit these mechanisms, however, their influence can be bypassed by other cells. Many antigen structures have been isolated in the uvea. With them it is possible to induce a model of autoimmune uveitis. The diagnostic value of eye specific and non-specific autoantibodies in uveitis patients was studied. In this report are show indications of autoimmune phenomena in the following diseases: sympathetic uveitis, Behçet's disease, Vogt-Koyanagi-Harada syndrome and birdshot retinopathy.

Dipole modelling of eye activity and its application to the removal of eye artefacts from the EEG and MEG

The spatio-temporal dipole model approach has been used to identify the difference dipoles arising from changes in the ocular dipoles due to eye movements and blinks. Based on these results a method has been developed to remove eye artefacts from electrical or magnetic data. The method avoids distortions due to the head model by determining the spatial distribution of the signals from the eyes empirically. Using simultaneous modelling of the EEG or MEG activity with dipole sources distributed within the head together with the empirically determined spatial eye components, the eye activity can be estimated and removed from the EEG or MEG. This greatly reduces the distortion to the topography that is a concomitant of previous eye artefact correction methods. The advantages of the method are illustrated using simulated and real electrical data.

Use of prior knowledge in brain electromagnetic source analysis

Using multichannel measurements of EEG and/or MEG, macroscopic source activities can be estimated in the human brain using brain electric source analysis (BESA, Scherg 1990). If a discrete number of brain areas is active, functional brain images which depict the locations and orientations of equivalent dipole sources as well as the dynamics of the local macroscopic currents can be obtained from such data--in principle--without external knowledge. However, given a certain number of sources or 'neural masses' (Freeman 1975) which contribute to an event related response (ERP), it can be difficult to find the correct solution due to background noise in the data and distortions from the head model. Prior knowledge based on anatomy and physiology can be useful to constrain spatial or temporal parameters of the model and to define better cost functions for fitting locations and orientations. An analysis of the auditory evoked N100 complex and of the auditory mismatch negativity (MMN) is presented which illustrates the use of spatial constraints. Also, the use of a modified cost function is demonstrated which limits source currents in certain time intervals.

Slow cortical potentials (SCPS) in schizophrenic patients during performance of the Wisconsin card-sorting test (WCST)

Fifteen schizophrenic patients (diagnosed according to DSM-III-R) and 15 age- and education-matched controls were tested on a computerized version of the Wisconsin card-sorting test (WCST). Slow Cortical Potentials (SCPs) were recorded throughout the performance from frontal, central and parietal electrode sites. As expected, the patients were impaired on the WCST, achieving fewer categories overall and incurring significantly more "unique" errors, although they were not significantly more perseverative than the controls. The patients did not display a generalized impairment in SCPs, differences between the groups emerging only before presentation of the key-cards and after presentation of the feedback regarding the correctness of the response. Neither the choice-card at the beginning of the trial, nor the presentation of the key-cards resulted in attenuated Evoked Potentials (EPs) in the patients. The lack of any abnormality in EPs suggests that the reason for the poor performances of schizophrenic patients on the WCST lies elsewhere than in perceptual stimulus processing. Contrary to expectations no specific impairment in frontal SCPs was detected.

Transduction of cellular neo mRNA by retrovirus-mediated recombination

Transduction of cellular oncogenes by retroviruses is thought to be a multistep process, involving transcriptional activation of a cellular gene by upstream proviral integration and joining of cellular DNA to retroviral transcriptional signals, followed by copackaging and recombination with a helper virus genome during reverse transcription. To examine the molecular mechanism of the reverse transcriptase-mediated recombination, we introduced into mouse fibroblast cells a variety of constructs in which the neo selectable marker was joined to flanking retroviruslike or cell-like sequences. After superinfection and copackaging with a replication-competent Mo-MuLVsupF virus, the formation of recombinant neo transducing viruses was assessed in a second round of virus infection by the ability to confer G418 resistance to infected cells. Our results showed that recombinant neo proviruses were generated from neo RNA containing either a 5' or 3' retroviral end, implying that one recombination event with helper virus RNA was sufficient to incorporate the neo gene into proviral DNA. Recombination occurred with an apparent frequency of 10(-4) to 10(-5) per replication cycle in the absence of homology between the two recombining partners. This frequency, however, increased at least 100-fold if homology was provided at the site of recombination. Our results support the hypothesis that neo-transducing viruses arise via reverse transcriptase-mediated recombination of RNA rather than by recombination proceeding through DNA intermediates. Unexpectedly, removal of the retroviral packaging site psi reduced the number of neo recombinants only slightly. Our data indicated that although RNAs lacking the psi site are poorly packaged into virions, those RNAs that are included in the virions undergo frequent recombination, even if there is no selection for recombination. Many of the neo recombinants formed with the psi- constructs had undergone additional recombinations and often incorporated the psi site from the helper RNA.

Spinal anaesthesia in day-care surgery with a 26-gauge needle

We studied 106 day-care surgical patients (52 male) aged 18-70 yr (mean 49.6 yr) who received spinal anaesthesia with a 26-gauge spinal needle. The incidence of headache, back pain and patient acceptability were investigated after operation using a questionnaire. The incidence of postspinal headache was 7.5%, and 11.3% of patients developed back pain. One patient remained in hospital because of hypotension and dizziness. There were no major complications and patient acceptability was almost 100%. We conclude that spinal anaesthesia for day-care surgery is easy to perform and cost effective.

[Surgical therapy of uveitis]

Cryotherapy is a good method of treating chronic uveitis, because it is minimally invasive and there are normally no complications. It has proved possible to reduce the frequency and intensity of inflammatory episodes, so that in many cases systemic drug therapy is superfluous. Stabilization or even regression of secondary conditions such as cystoid macular edema or cataract has been achieved, a phenomenon also observed among the present authors' own patients. In cases which did not respond to cryotherapy or where there were severe vitreous opacities vitrectomy was performed. A total of 207 eyes were followed up, on average for 1 1/2 years. During this time visual acuity remained stable or improved in 76% of those treated by cryotherapy, and in over 86% of those treated by vitrectomy.

Renaturation of complementary DNA strands mediated by purified mammalian heterogeneous nuclear ribonucleoprotein A1 protein: implications for a mechanism for rapid molecular assembly

Purified heterogeneous nuclear ribonucleoprotein (hnRNP) A1 protein, which is found in vivo associated with heterogeneous nuclear RNA (hnRNA), promotes the rapid renaturation of nucleic acid strands. Maximal renaturation activity requires the glycine-rich carboxyl-terminal one-third of the protein, although the amino-terminal two-thirds also has activity. The A1-mediated reaction is second-order with respect to complementary DNA concentration, and the renaturation rate constant at 37 degrees C with A1 is about 3000-fold greater than in the absence of the protein. At 60 degrees C, the A1-mediated renaturation rate is even faster, and is about 300-fold greater than protein-free reactions carried out at 68 degrees C in 1 M NaCl. Provided that sufficient A1 protein is present to coat all strands in solution, the presence of nonhomologous, single-stranded DNA does not significantly inhibit the reaction. Moreover, renaturation of short strands to their complement contained in very long strands is nearly as efficient as between two short strands. These results indicate that A1 may be useful for procedures that rely on nucleic acid renaturation. We propose that A1 promotes rapid renaturation primarily by reducing the entropic barrier of bimolecular strand association through relatively transient interactions between A1-coated strands. Such interactions, mediated by flexible repeating domains, may act generally to increase the association kinetics of highly specific molecular assemblies in processes such as RNA maturation, transcription, translation, and transport.

[Duodenal leiomyoblastoma. Apropos of a new case and review of the literature]

The authors report a new case of duodenal leiomyoblastoma. Since local anatomical factors were favorable, the tumor was removed by resecting the entire second portion of duodenum with reanastomosis of the remaining ends. This case can be added to the very small number of cases reported in the literature regarding leiomyoblastoma at this site in the gastrointestinal tract. Since diagnostic is difficult, and often made per-operatively following and acute complication, a precise topographical study of the region needs to be performed. It is only by this means that a completely safe operative procedure may be chosen and performed. From an anatomo-pathological viewpoint, several criteria exist to distinguish the potentially benign from the potentially malignant form. However, this remains to be confirmed given the controversial aspects of the subject. Study has mainly involved gastric localisations where a greater number of lesions have been found. At present, only time will show whether these tumors are benign or malignant.

[Measurement of the sealing impression during the cerclage operation]

In hypotensive or hypertensive eyes (i.e., in the treatment of perforating injuries), choosing an ideal length for the plaque is often difficult. The goal of the procedure is to achieve a sufficient depth of the impression. However, excessive depth must be avoided, since this could lead to String syndrome and scleral necrosis. On the basis of an analysis of ocular geometry it proved possible to calculate the circumference of the globe in the region of the cerclage, and from this the ideal length of the plaque. When silicone foam plaques are used it is between 70.4 mm when attached close to the muscle insertion and a maximum of 74.1 mm when placed on the equator of the bulb. Basing surgery on this calculation method in more than 300 patients, no complications such as String syndrome, scleral necrosis or secondary glaucoma were observed. A chronic inflammatory reaction to the scleral buckle was seen in three cases. In order to avoid this complication, caused by the enormous volume of the cylindrical silicone plaque, splitting or flattening of the plaque is recommended.

Gene targeting at the human CD4 locus by epitope addition

Homologous recombination at the CD4 locus in a human T-cell line has been achieved by an approach called epitope addition. The endogenous CD4 gene provided transcription, translation, and leader sequences to a crippled introduced Thy-1 gene, resulting in the expression of murine Thy-1 epitopes on the surface of the human cells. Thy-1+ cells were selected using the Fluorescence Activated Cell Sorter (FACS). An estimated 700-fold enrichment for homologous versus nonhomologous integration events was obtained, such that 70% of cells scoring positive for Thy-1 were derived from gene targeting. Three of the Thy-1+ cell lines expressed protein only from the targeted allele; thus, these cells were functionally CD4-.

[Measurement of arterial pressure using 3 measurement methods in medial arterial calcification]

Medial calcification of the arteries, because of non-distensibility of the blood vessel walls, may overestimate the real intra-arterial pressure when blood pressure (BP) is measured by indirect sphygmomanometry cuff. In order to assess the best method for measuring BP, we compared direct intra-arterial measurements with indirect cuff sphygmomanometry as well as automatic oscillometric measurements in 15 hypertensive patients. Mean age +/- standard deviation (SD) was 62 +/- 9 years; all patients had medial calcifications of forearm and/or brachial arteries, and Osler's maneuver was negative in all. Ten sets of direct and indirect BP measurements were obtained for each patient. Results are expressed as mean +/- SD: (table; see text) There was no significant difference between cuff pressure and systolic intra-arterial pressure. The automatic oscillometric method underestimated systolic intra-arterial BP. Great individual variability was observed and could not be predicted clinically. Indirect diastolic BP values were greater than intra-arterial BP in all patients with the sphygmomanometer cuff and in 10 patients with the oscillometric recorder. There existed a direct relation between intra-arterial BP and differences between indirect BP measurements and intra-arterial BP as follows: intra-arterial BP was overestimated by indirect methods for values under 150 mmHg, and underestimated above 150 mmHg. In conclusion, invasive intra-arterial BP measurement seem to be necessary to distinguish between hypertensive and pseudo-hypertensive patients, in case of radiologic evidence of arterial calcification.

Two stages of care for pleural effusion

When the patient's pleural space is filled with fluid, palliative treatment measures--thoracic drainage and pleurodesis--and diligent nursing care can help her breathe easier.

Homologous integration in mammalian cells without target gene selection

Homologous integrations into a nonselectable target locus have been highly enriched for following DNA transfections into mammalian cells. The target gene, the SV40 early region in COS1 cells, provides transcription signals to activate a defective selectable marker, the gpt gene. We find that nearly half of the selected clones have integrated the gpt gene at the homologous sequence in the COS1 genome. This is an estimated 100-fold enrichment for homologous events compared with transfections in which the gpt gene is transcriptionally active. As shown for yeast integration events, a double-strand break at a position of homology between the transfected DNA and the genomic target is necessary to achieve a high frequency of homologous integrations. Furthermore, the arrangement of sequences at the integration site includes a repair of the double-strand gap, which was present on the transfected DNA, suggesting that similarities exist between yeast and mammalian integrations. The experimental design, in which a defective marker is activated following a homologous integration, may have general applications for gene targeting in mammalian cells.

Comparison of intron-dependent and intron-independent gene expression

Recombinant simian virus 40 viruses carrying rabbit beta-globin cDNA failed to express the beta-globin sequence unless an intron was included in the transcription unit. The addition of either beta-globin IVS1 or IVS2 caused a 400-fold increase in RNA production. Stable beta-globin RNA production required sequences in IVS2 that were very close to the splice sites and that coincided with those needed for mRNA splicing. In addition to the recombinant viruses, intron-dependent expression was observed with both replicating and nonreplicating plasmid vectors in short-term transfections of cultured animal cells. Unlike transcriptional enhancer elements, IVS2 failed to increase stable RNA production when it was placed downstream of the polyadenylation site. Using a plasmid vector system to survey different inserted sequences for their dependence on introns for expression, we found that the presence of IVS2 stimulated the expression of these sequences 2- to 500-fold. Sequences from the transcribed region of the herpes simplex virus thymidine kinase gene, a gene that lacks an intervening sequence, permitted substantial intron-independent expression (greater than 100-fold increase) in the plasmid vector system.

Conservation of short patches of amino acid sequence amongst proteins with a common function but evolutionarily distinct origins: implications for cloning genes and for structure-function analysis

Small patches of identical amino acid sequences commonly occur in proteins that have the same function but are derived from evolutionarily distant organisms. Reverse translation of such patches into degenerate pools of oligonucleotides provide useful hybridization probes for cloning the gene for the corresponding protein from other organisms. Since the conserved patches of identical amino acid sequence are probably important for the protein's biological function, they are preferred targets for reverse genetic studies aimed at defining structure-function relationships.

Epstein-Barr virus shuttle vector for stable episomal replication of cDNA expression libraries in human cells

Efficient transfection and expression of cDNA libraries in human cells has been achieved with an Epstein-Barr virus-based subcloning vector (EBO-pcD). The plasmid vector contains a resistance marker for hygromycin B to permit selection for transformed cells. The Epstein-Barr virus origin for plasmid replication (oriP) and the Epstein-Barr virus nuclear antigen gene have also been incorporated into the vector to ensure that the plasmids are maintained stably and extrachromosomally. Human lymphoblastoid cells can be stably transformed at high efficiency (10 to 15%) by such plasmids, thereby permitting the ready isolation of 10(6) to 10(7) independent transformants. Consequently, entire high-complexity EBO-pcD expression libraries can be introduced into these cells. Furthermore, since EBO-pcD plasmids are maintained as episomes at two to eight copies per cell, intact cDNA clones can be readily isolated from transformants and recovered by propagation in Escherichia coli. By using such vectors, human cells have been stably transformed with EBO-pcD-hprt to express hypoxanthine-guanine phosphoribosyltransferase and with EBO-pcD-Leu-2 to express the human T-cell surface marker Leu-2 (CD8). Reconstruction experiments with mixtures of EBO-pcD plasmids demonstrated that one clone of EBO-pcD-hprt per 10(6) total clones or one clone of EBO-pcD-Leu-2 per 2 x 10(4) total clones can be recovered intact from the transformed cells. The ability to directly select for expression of very rare EBO-pcD clones and to then recover these episomes should make it possible to clone certain genes where hybridization and immunological screening methods are not applicable but where a phenotype can be scored or selected in human cell lines.

Complications of prophylactic argon laser treatment of retinal breaks and degenerations in 2,000 eyes

The decision to treat retinal breaks and degenerations prophylactically should be made with an awareness of the incidence of complications associated with argon laser photocoagulation (ALP). We evaluated retrospectively 2,000 eyes with retinal breaks and degenerations treated with ALP, with follow-up from 6 to 84 months (mean 46 months). The only complications during photocoagulation were petectal intra- and preretinal hemorrhages, which absorbed after a few days. Complications after treatment were limited to epiretinal membrane formation in the macular area in four eyes (0.2%). The applied laser energy in three of these four eyes was significantly greater (mean 34.4 mJ) than in the total 2,000 eyes (mean 7.2 mJ). This finding supports the observation by other authors that extensive photocoagulation is associated with an increased incidence of epiretinal membrane formation.

Cloning and characterization of a cDNA encoding human galactose-1-phosphate uridyl transferase

We report the cloning and characterization of a cDNA that encodes a functional human galactose-1-phosphate uridyl transferase (GALT). The cDNA is 1400 bases in length and encodes a 43,000 Mr protein. The cloning strategy involved the identification of short peptide sequences conserved between the homologous enzymes from Escherichia coli and yeast, and the construction of oligonucleotide pools corresponding to the conserved patches. These patches of conserved amino acids tend to be conserved in humans as well.

Eyeblink-related potentials

When the EEG is averaged time-locked to blinks, and the part of the potential that is proportional to the EOG is subtracted, a signal (the 'residuum') remains which resembles an event-related potential (ERP). The blink time-locked average (BTA) was investigated to determine whether the components of the residuum are due to a cerebral blink-related potential or to artifacts of the EOG which subtraction failed to remove. The BTA was obtained from 12 subjects using voluntary blinking in the light and in complete darkness. Differences between the potentials in light and dark indicate that a major component of the residuum is a visual evoked response elicited by the off-on light stimulus associated with blink eye closure. The results are discussed in relation to attempts to correct blink artifacts in ERP experiments and, by drawing parallels between the residuum and the lambda potential associated with saccades, similar inferences are made for the correction of eye movement artifacts.