Advances in process control.

Advances in electronics and computers have enabled industries to attain better control of their processes with resulting increases in quality, productivity, profitability, and compliance with government regulations. With a hierarchy of computers, distributed data acquisition, and information processing and control, it is possible to achieve overall optimum performance of a plant. While further advances in microprocessors and large-scale integration will be useful to the process engineer, major improvements in process control await advances in sensor technology and software.

Static mechanics of the velopharynx of patients with obstructive sleep apnea.

The static mechanics of the hypotonic pharynx were endoscopically evaluated in nine sleeping patients with obstructive sleep apnea, having a primary narrowing only at the velopharynx. The velopharynx closed completely at a mean pressure of 0.18 +/- 1.21 cmH2O, and the mean half-dilation pressure was 1.93 cmH2O above closing pressure. The dependence of area on pressure was distinctly curvilinear, being steep near closing pressure and asymptotically approaching maximum area (mean = 1.32 cm2). The data for each patient were satisfactorily fitted by an exponential function (mean R2 = 0.98), and a single exponential relationship usefully represented the dependence of relative area on pressure above closing pressure for the population (R2 = 0.85). During the test inspiration, flow limitation was consistently observed when mask pressure exceeded closing pressure by 0.5-3.0 cmH2O. In summary, the static mechanics of the hypotonic velopharynx of patients with obstructive sleep apnea can be described by an exponential pressure-area relationship, with a closing pressure near atmospheric pressure and a high compliance in the range of airway pressure 0-3 cmH2O above closing pressure.

Preoperative assessment for lung transplantation.

Lung transplantation has evolved from an intellectual curiosity to a viable therapeutic option in a selected number of patients with end-stage lung disease. The indications for single lung, double lung, or heart-lung transplantation at major North American transplant centers are presented, the selection criteria are discussed, and the standard preoperative evaluation is outlined. Utilizing these guidelines, a 1-year actuarial survival following each of these procedures of greater than 60% can be expected.

Factors influencing mode of claims settlement in workers' compensation cases.

This paper examines the variables that influence the means by which 10,192 injured workers settled their compensation claims during 1990. The data on which this study is based come from a state in Australia where there are three means by which workers' compensation claims can be settled by lump sum payment: settlement following a specific injury payment, early settlement payment and settlement following a common law payment. This paper is specifically concerned with identifying the variables that determine whether the claim will be settled by a lump sum payment and whether different modes of claims settlement by lump sum are unique and predictable from a range of variables that include injury characteristics and demographics. The results of logistic regression modelling revealed that those who received a lump sum settlement could be reliably distinguished from those who did not receive such a payment. Each mode of settlement varied in the extent to which it could be predicted. Contrary to expectations, the most difficult form of settlement mode to predict was that of specific injury payments (4% accurate) with the most predictive being early settlement payments (81% accurate). Common law payments were also highly predictable (48% accurate). The form of lump sum payment received by injured workers was found to depend on a range of injury characteristics, indices of severity and for common law payments, gender and potential income loss. It is argued that although injury characteristics play a part in the process of claims settlement, personal circumstances and insurance company policies are influential in dictating the form by which workers compensation cases are finalized.

Congenital muscular torticollis: observations regarding clinical findings, associated conditions, and results of treatment.

Of the 232 patients with a diagnosis of congenital muscular torticollis, more than one-half were initially revealed before 3 weeks of age. The most common presentation at the initial clinical evaluation was head tilt. A surprisingly high incidence of associated conditions including hip dysplasia and lower extremity changes was seen. As a consequence all patients with a diagnosis of congenital muscular torticollis underwent a careful clinical review and roentgenographic examination of the entire spine and hips. Good or excellent results were achieved in all children diagnosed and treated under 1 year of age utilizing conservative measures. In the older child satisfactory results were seen for the primarily cosmetic deformity when surgically approached using an open distal myectomy. There appears to be no justification for a surgical approach in the child with congenital muscular torticollis under 1 year of age.

Who goes to GROW?

GROW is a self help group which commenced in Sydney 30 years ago to assist mental patients rehabilitate. Some fear that this is not occurring. This study aimed to assess, by questionnaires, the mental health status of GROW attenders in Western Australia. There was a 93% response rate with demographic variables similar to an earlier Australia-wide survey. Individual scores on the GHQ and a Work, Leisure and Family Life Questionnaire showed a higher level of dysfunction than that in a "normal" population with men, on the average, scoring higher than women. Questions on medical care indicated that between 50-70% of attenders had previously been treated for a nervous condition. It is concluded that GROW is reaching a group of people with significant mental morbidity.

Understanding and selecting monitoring equipment in anaesthesia and intensive care.

Techniques for sensing, acquiring, processing and displaying physiological variables used to assist the process of monitoring in anaesthesia and intensive care have been reviewed. The role of instrumental monitoring in clinical practice and the comparative effectiveness of Man versus Machine has been outlined. Future developments in monitoring in clinical practice have been identified. It is important that physicians stay abreast of developments in the technology of measurement and monitoring instrumentation so that they not only assist in the development of standards but also have a complete understanding of the precision and real usefulness of any given item of equipment. To this end, guidelines have been tabulated which may permit those who have the responsibility for acquiring updating or using monitoring equipment, to more completely examine the features of any apparatus which is being considered for purchase.

Factors influencing the cost of workers' compensation claims: The effects of settlement method, injury characteristics, and demographics.

This paper estimates an empirical model of the total costs of finalised workers' compensation claims. The sample was comprised of 8232 claims, made by workers in Western Australia, that were closed in 1990. It is reported that the variables representing the method of claim settlement is an important determinant of the cost of individual workers' compensation claims. In addition, it is also found that type of injury, gender, age, and occupational classification have significant effects on the model. Workers who, sustain musculoskeletal injuries, are male, and/or who are white collar workers incur significantly more costs. In addition to these effects, a positive linear relationship between age and costs was also observed. The empirical models, of the kind specified in this paper, may be capable of performing a useful prescriptive role in rehabilitation programs. Such models can enable "problematic" cases to be identified early in the claim process, so that they might be appropriately referred for intensive rehabilitation intervention.

Temporal branch retinal vein obstruction masquerading as a retinal arterial macroaneurysm: the Bonet sign.

We present the case report of a patient with a hemorrhage at an arteriovenous crossing which was erroneously interpreted as being an arterial macroaneurysm. Shortly thereafter, the typical appearance of a temporal branch retinal vein obstruction was evident indicating that the hemorrhage was an early sign of the venous obstruction. This sign (the Bonet sign) should alert the clinician to this disorder so that the correct diagnosis and recommendations for patient care can be undertaken.

Cavitary aspergillosis as a complication of AIDS.

The authors report the radiographic findings in two patients with the human immunodeficiency virus (HIV) who presented with cavitary lung disease caused by Aspergillus. Recognition of the disease in one of the patients led to successful medical therapy. Disease due to Aspergillus must be considered in HIV-positive patients with cystic or cavitary disease appearing in chest radiographs.

Review of choroidal osteoma: successful krypton red laser photocoagulation of an associated subretinal neovascular membrane involving the fovea.

Laser treatment of a subretinal neovascular membrane associated with a unilateral choroidal osteoma in a 28-year-old woman is described. To our knowledge, this is the first reported use of krypton red laser photocoagulation for the initial treatment of a subfoveal neovascular membrane in this setting. Early recognition of the membrane allowed treatment prior to involvement of the central fovea. Follow-up has shown obliteration of the membrane without recurrence and 20/20 vision. We emphasize recognition of this unusual tumor, self-monitoring with an Amsler grid, and early treatment of subretinal neovascularization in this high risk group of young patients.

Central retinal-artery occlusion in proliferative sickle-cell retinopathy after retrobulbar injection.

Central retinal-artery obstruction (CRAO) is a devastating complication after retrobulbar anesthesia, a procedure which was previously recommended routinely to immobilize the eye and reduce discomfort during laser surgery. Recent developments in treatment technique, involving scatter laser applications given over several sessions with smaller spot sizes and shorter durations, have virtually eliminated the need for retrobulbar injections and the risks of retrobulbar hemorrhage, which can cause increased intraocular pressure and culminate in closure of the arterial circulation. We present the case of a patient with proliferative sickle retinopathy who sustained such a complication after direct photocoagulation treatment of sea-fans elsewhere and offer alternative treatment techniques which we have used for the past ten years that eliminate this hazard.

Progressive capillary nonperfusion in temporal branch retinal vein obstruction.

We studied 31 eyes with nonischemic temporal branch retinal vein obstruction (TBRVO) of six months' duration or less. Each eye had an initial and at least one follow-up fluorescein angiogram according to the clinical course. Five eyes had sufficient additional capillary nonperfusion by angiography to warrant reclassification into the ischemic category. This conversion to an ischemic TBRVO pattern was documented as early as one month and as late as 14 months (average 5.2 months) after initial evaluation. Males dominated the progressive group (P less than 0.005); age, sex, initial visual acuity, and associated medical and ocular conditions were not significantly different between progressive and nonprogressive eyes (P greater than 0.05). A nonischemic TBRVO may convert to an ischemic pattern, placing these eyes at increased risk for the subsequent development of neovascular complications.

Phosphorylation and activation of smooth muscle myosin light chain kinase by MAP kinase and cyclin-dependent kinase-1.

Smooth muscle myosin light chain kinase (MLCK) features several consensus sites of phosphorylation by proline-directed protein serine/threonine kinases. The phosphorylation of MLCK by two proline-directed kinases isolated from sea star oocytes, i.e., p44mpk (Mpk, a mitogen-activated protein kinase homologue) and cyclin-dependent kinase-1 (CDK1, also known as p34cdc2), was investigated. Chicken gizzard MLCK was phosphorylated on seryl and threonyl residues by both Mpk and CDK1. Phosphorylation of MLCK to 0.6 mol Pi/mol by Mpk increased the Vmax of phosphotransferase activity towards a synthetic peptide corresponding to residues 11-23 of the 20-kDa light chain of myosin by 1.6-fold. Phosphorylation of MLCK to 1.0 mol Pi/mol by CDK1 increased the Vmax by 2.3-fold. Phosphorylation by either kinase had no significant effect on the concentration of calmodulin required for half-maximal activation of MLCK. Analysis of the phosphorylation of synthetic peptides containing consensus phosphorylation sites for Mpk and CDK1 indicated that the major site of phosphorylation in MLCK by Mpk was Ser-834, and by CDK1 was Thr-283. Both of these sites are located outside the calmodulin-binding site (residues 796-815), consistent with the observation that phosphorylation by Mpk or CDK1 was unaffected by the presence of bound Ca2+/calmodulin. These results indicate that MLCK activity may be regulated by phosphorylation catalyzed by proline-directed kinases, possibly directed at Thr-40 and Thr-43 at the amino terminus of MLCK.

Regulation of the meiosis-inhibited protein kinase, a p38(MAPK) isoform, during meiosis and following fertilization of seastar oocytes.

A p38(MAPK) homolog Mipk (meiosis-inhibited protein kinase) was cloned from seastar oocytes. This 40-kDa protein shares approximately 65% amino acid identity with mammalian p38-alpha isoforms. Mipk was one of the major tyrosine-phosphorylated proteins in immature oocytes arrested at the G(2)/M transition of meiosis I. The tyrosine phosphorylation of Mipk was increased in response to anisomycin, heat, and osmotic shock of oocytes. During 1-methyladenine-induced oocyte maturation, Mipk underwent tyrosine dephosphorylation and remained dephosphorylated in mature oocytes and during the early mitotic cell divisions until approximately 12 h after fertilization. At the time of differentiation and acquisition of G phases in the developing embryos, Mipk was rephosphorylated on tyrosine. In oocytes that were microinjected with Mipk antisense oligonucleotides and subsequently were allowed to mature and become fertilized, differentiation was blocked. Because MipK antisense oligonucleotides and a dominant-negative (K62R)Mipk when microinjected into immature oocytes failed to induce germinal vesicle breakdown, inhibition of Mipk function was not sufficient by itself to cause oocyte maturation. These findings point to a putative role for Mipk in cell cycle control as a G-phase-promoting factor.

Pharyngeal narrowing and closing pressures in patients with obstructive sleep apnea.

Based on previous studies, we hypothesized that the pharynx collapses at multiple sites in most patients with obstructive sleep apnea (OSA). The purpose of this study was to document, in a population of apneic subjects, the site(s) of narrowing and closing pressure of the hypotonic pharynx. We endoscopically examined the pharynx in 45 OSA patients during sleep while they received nasal continuous positive airway pressure (CPAP), which produces hypotonia of pharyngeal muscles. Intrapharyngeal images and pressures were obtained at the end of expiration during single-breath tests (SBT). The fractional narrowing (FN) of each pharyngeal segment (nasopharynx, oropharynx, and hypopharynx) was calculated as the relative change in area when nasal airway pressure was reduced from a pressure that held the pharynx fully distended to the pressure at which the airway closed. The frequency distribution of FN for the nasopharynx was skewed toward larger values, and the frequency was relatively evenly distributed for the oropharynx and hypopharynx. A site having FN greater than 0.75 was defined as a site of primary narrowing, and a site showing FN 0.25 to 0.75 was defined as a site of secondary narrowing. The nasopharynx was a site of primary narrowing in 80% of patients, and two or more sites of narrowing were commonly observed (82%). Four categories of combined narrowing were identified: (1) primary narrowing only at the nasopharynx (18%); (2) primary narrowing at the nasopharynx plus other sites of secondary narrowing (40%); (3) primary narrowing at the nasopharynx plus other sites of primary narrowing (22%); and (4) other patterns (20%).(ABSTRACT TRUNCATED AT 250 WORDS)