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An apparatus used in undergraduate instrumentation teaching is described. A small wind tunnel creates air speeds up to 12 m/s. A Pitot tube is used as a reference against which a hot wire anemometer is compared for linearity and transient response. The experiment serves to introduce non-ideal systems.

Crystals were produced from variant surface glycoproteins (VSG) of Trypanosoma brucei brucei antigenic variants MITat 1.2, 1.6, and ILTat 1.22, 1.23, 1.24, 1.25, and 1.26. Purified VSGs had molecular weights from 60,000 to 68,000 on sodium dodecyl sulfate-polyacrylamide gels, whereas the crystals obtained were composed of polypeptides of approximate Mr 40,000-50,000. Amino-terminal amino acid sequences determined from the crystallized VSGs were identical to sequences obtained from the respective intact proteins, indicating that the crystals contained VSG amino-terminal fragments. Crystallization conditions and lattice dimensions of the crystals are given.

Decay-accelerating factor (DAF) is an integral membrane protein that inhibits amplification of the complement cascade on the cell surface. We and other investigators have shown that DAF is part of a newly characterized family of proteins that are anchored to the cell membrane by phosphatidylinositol (PI). The group includes the variant surface glycoprotein (VSG) of African trypanosomes, the p63 protein of Leishmania, acetylcholinesterase (AChE), alkaline phosphatase, Thy-1, 5'-nucleotidase, and RT6.2--an alloantigen from rat T cells. The structure of the membrane anchor has been best characterized for VSG, but chemical studies of the membrane anchors of AChE and Thy-1 suggest that similar glycolipid moieties anchor these proteins to the cell surface. In the VSG, the membrane anchor consists of an ethanolamine linked covalently to an oligosaccharide and glucosamine; the entire complex is anchored to the cell membrane by PI. Immunologically, this glycolipid defines an epitope, the cross-reacting determinant (CRD), that is only revealed after removal of the diacyl glycerol anchor by a phospholipase C. By Western blotting, we show here that DAF-S (DAF released from the membrane by PI-specific phospholipase C [PIPLC]) also contains CRD. Using a newly developed immunoradiometric assay (IRMA) in which the solid-phase capturing antibody is a monoclonal antibody to DAF and the second antibody is anti-CRD, we have been able to quantitate DAF-S. By IRMA, we show that the reaction between anti-CRD and DAF-S is specific, since the binding is competitively inhibited only by the soluble form of the VSG. These observations further support the concept that the glycolipid anchors of this new family of proteins have similar structures. DAF is also found as a soluble protein in various tissue fluids as well as in Hela cell supernatants. No evidence for the presence of the CRD epitope was found on these proteins, suggesting that these forms of DAF are not released from the surface of cells by endogenous phospholipases.

Bacteriological examinations were performed on 1103 infants to determine the ages at which the newborn are colonized at different sites by bacteria, and with which organisms. On the day of birth, specimens for culture included aspirated gastric contents, and swabs from nose, throat, groin and rectum; on Day 3 the umbilical cord clamp with a section of the cord, swabs from nose, throat, groin and rectum; on days 5 and 1, and weekly thereafter, swabs from the same 4 sites. These examinations included identification of the individual bacterial species. The mass of information so obtained was analysed by computer. The high level of bacterial colonization by day 3 was striking and, indeed, large numbers of potential pathogens were grown from infants within one hour of birth. Staphylococcus aureus was found only in very small numbers of infants, e.g. only 2.6 per cent of infants' umbilical cords on day 3, and 4 per cent of infants' noses on day 7. If the levels of colonization reflect the risks of infection, Pseudomonas aeruginosa ranks close to Staph. aureus in the newborn nursery of the modern maternity hospital. Forty two different species of bacteria were isolated from these infants of which 24 were potential pathogens and of the latter, gram-negative organisms greatly outnumbered the gram-positive. This high incidence of gram-negative colonization in a large series of hospitalized neonates may be a normal phenomenon but it suggests that the risk of infection is today greater with gram-negative than with gram-positive bacteria. The figures for carriage of pathogenic staphylococci in the present investigation contrast markedly with the figures reported by many workers between 1950 and 1960.

SUMMARYThe isolation of polysomes in bulk from bloodstream forms ofTrypanosoma bruceiis described. The polysomes are active inin vitroprotein synthesis in the presence or absence of initiation inhibitors. Nascent variant surface antigen (VSA) has been detected on these polysomes using purified radio-iodinated antibody. EDTA-induced ribosomal sub-units and their large rRNA's are characterized. The 26S rRNA is nicked to produce 2 molecules which are both smaller than the 195 rRNA of the small sub-unit which is larger than that found in the majority of eukaryotic small sub-units.

We show that the technique of exciting a differential pressure transducer at one port to measure its differential gain yields incorrect results in the case of asymmetrical differential pressure transducers but is acceptable in the case of symmetrical transducers. We have measured the common-mode gain of a symmetrical and an asymmetrical differential pressure transducer from 1 Hz to 100 Hz, both directly and by computation from differential gain measurements. No compensation for common-mode error is necessary when a symmetrical transducer is used in mechanically ventilated neonates. We have also measured the frequency response of neonatal Fleisch and screen pneumotachographs connected to Validyne MP45 differential pressure transducers in air, 60% oxygen and 100% oxygen, and concluded that the effect of oxygen concentration is small below 40 Hz. However, the normalised frequency response of the flow transducer differs markedly from unity at frequencies inside the flow bandwidth generated by neonatal pressure cycled ventilators and dynamic correction is therefore necessary.

A panel of variant-specific mAb has been raised against the Trypanosoma brucei variant MITat 1.2. The binding characteristics of these mAb have been determined by a combination of immunofluorescence assays, using living or fixed trypanosomes, and solid phase assays, using purified variant surface glycoprotein. In addition, these mAb have been tested for their ability to neutralize MITat 1.2 infections in mice. Finally, the epitopes recognized by the mAb have been defined by competitive binding assays. These results are discussed with respect to the structural organization of the surface coat of T. brucei.

Studies have been made of the effect of Cd2+ on the oxidation rate of C3H8 in 80% H3PO4 at 130δ C on platinized Pt electrodes. Dissolved Cd2+ discharges, probably as Cd0, and forms a stable sub-monolayer on a Pt electrode at potentials as high as 0·5 V versus RHE. Although this Cd0 layer is apparently substantially desorbed in favor of adsorbed hydrocarbon, C3H8 adsorption is inhibited in its presence. C3H8 oxidation is also inhibited. However, the C3H8 oxidation rate is observed to increase under some circumstances, and this appears to be because Cd isabsorbed into the Pt lattice. Co-plating of Cd and Pt leads to an electrode which, once the excess Cd has been removed, appears to be stable, and which catalyses C3H8 oxidation by about a factor of three at 0·25 V. Above 0·3 V, this absorbed Cd somewhat inhibits C3H8 oxidation.

The purification of detergent-solubilized rat histocompatibility antigens is described. The antigen may readily be incorporated into synthetic vesicles (liposomes) which appear to be unilamellar and between 0.1 microbeter and 0.2 micrometer in diameter. The addition of specific antibody leads to the agglutination and precipitation of the liposomes. An enzyme, horseradish peroxidase, may be incorporated into the trapped aqueous phase of the liposome, and its release by antibody and complement can be detected.

Purified variant specific antigens of Trypanosoma brucei were shown to exist in solution as dimers, and occasionally as higher oligomers, as judged by gel filtration and by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis after treatment with bifunctional cross-linking reagents.

Serotypes of 93 Australian isolates of Erysipelothrix rhusiopathiae from diseased domestic animals and poultry and a variety of captive wild birds and animals were determined by double diffusion gel precipitation. Two isolates, from the faeces of a swallow were also examined. Serotypes 1a, 1b and 2 were isolated from pigs and serotypes 1a, 1b, 2, 5, 15 and 21 from sheep or goats. Erysipelas in poultry was attributed to serotypes 1b, 5, 15 and 16. In captive wild birds serotypes 1b, 5, 6, 8, 14, 21 and an isolate reactive with antiserum to strain Seehecht were associated with septicaemic deaths. Single isolates from tissues of a bilby (Macrotis lagotis), black rat (Rattus rattus), brown snake (Pseudechis australis) and a bandicoot (Isoodon macrouris) were classified as serotypes 4, 4, 7, and 10 respectively. Six isolates were not able to be typed. Serotype 1b was the most widely distributed and most common (28%), being associated with disease in pigs, sheep, poultry and wild birds. Serotypes 1a or 2 were found in a more restricted range of animals, being commonly associated with erysipelas in pigs, less commonly in sheep and infrequently in other species. From diseased pigs, 26 of 33 isolates (79%) were serotypes 1a and 1b.

The incorporation of HLA antigens into liposomes is described. At and above the lipidphase-transition temperature, between 50 and 80% of the added antigenic activity may be incorporated into liposomes in the form of multilamellar vesicles. The antigen appears to be asymmetrically orientated with respect to the lipid bilayer.

Conventional chest tomography and fibreoptic bronchoscopy were performed in 100 patients with a localised chest abnormality on their chest radiographs who had been referred with a possible diagnosis of bronchial carcinoma. Carcinoma was eventually confirmed in 74 cases and in 26 the lesion proved to be benign. The accuracy of tomography in the overall series was 83%, with a sensitivity of 92% and a specificity of 58%. These figures compare favourably with the results of other imaging techniques used in the diagnosis of bronchial carcinoma. In 50 patients bronchoscopy did not suggest carcinoma and in this group of patients 24 had a carcinoma and 26 a benign lesion. The accuracy of tomography in the bronchoscopy negative patients was 74%, the major source of error being the false positive category. The lesion eventually proved to be benign in 33% of the cases where tomography suggested malignancy, but when the tomograms suggested that the lesion was benign a tumour was found to be present in only 12% of cases.

Thirty patients undergoing anterior resection of the rectum were randomized for postoperative drainage with either corrugated (N = 14) or corrugated plus Shirley sump drain (N = 16). Drainage volume per 24 hours was measured, and volume of residual pelvic fluid collection estimated by CT scan on the seventh postoperative day. A mean of 591.9 +/- 415.2 ml of fluid drained during the first seven postoperative days. There was a significant (P less than 0.01) increase in 24 hour drainage volume between the fourth and sixth postoperative days. There was no significant difference in drainage volumes between the two drainage methods. Residual pelvic fluid collection (median volume, 16 ml) was detected in 80 percent of patients at one week after operation. While this was larger (24 ml median) for the corrugated only group compared with the corrugated plus sump drain group (11.5 ml median), the difference was not significant. Fluid loss during the first postoperative week (616.6 +/- 424.2 ml) was significantly (P less than 0.05) less when the anastomosis was situated higher than 12 cm (294 +/- 192 ml) compared with 6 to 12 cm from the anal margin (496 +/- 210 ml), or after coloanal anastomosis (1077 +/- 432 ml). Residual pelvic fluid collection was larger after coloanal anastomosis (median, 33 ml; range, 1.5 to 90 ml) compared with 6 to 12 cm (median, 11 ml; range, 0-124 ml) or higher than 12 cm (median 9 ml; range, 0 to 16 ml) from the anal margin, but the difference was not significant. Drainage after anterior resection is important because large volumes of serosanguineous fluid collect, especially after resection of low tumors. Neither of the drainage methods tested in this study prevented persisting pelvic fluid collection at the seventh postoperative day.

The variant surface glycoprotein (VSG) of the African trypanosome is anchored in the cell membrane by a complex glycan attached to phosphatidylinositol. The carboxyl terminal portion of VSG contains a cryptic carbohydrate epitope, the cross-reacting determinant (CRD), that is revealed only after removal of the diacylglycerol by phosphatidylinositol-specific phospholipase C (PIPLC) or VSG lipase. Recently, we have shown that after hydrolysis by PIPLC, decay-accelerating factor (DAF)--a mammalian phosphatidylinositol-anchored protein--also contains the CRD epitope. Using a two site immunoradiometric assay in which the capturing antibody is a monoclonal antibody to DAF and the revealing antibody is anti-CRD, we now show that sugar phosphates significantly inhibited the binding of anti-CRD antibody to DAF released by PIPLC. DL-myo-inositol 1,2-cyclic phosphate was the most potent inhibitor of binding (IC50 less than 10(-8) M). Other sugar phosphates, such as alpha-D-glucose-1-phosphate, which also possess adjacent hydroxyl and phosphate moieties in cis also inhibited binding at low concentrations (IC50 = 10(-5) to 10(-4) M). In contrast, sugar phosphates which do not possess adjacent hydroxyl and phosphate moieties in cis and simple sugars weakly inhibited binding (IC50 greater than 10(-3) M). These results suggest that myo-inositol 1,2-cyclic phosphate contributes significantly to the epitope recognized by the anti-CRD antibody and is consistent with analysis of the carboxyl terminus of VSG, which also suggested the presence of the cyclic inositol phosphate. In light of the recent findings that human serum contains a glycan-phosphatidyl-inositol-specific phospholipase D, which converts DAF from a hydrophobic to a hydrophilic form lacking the CRD, the observation that the phosphate is crucial for expression of the epitope may be relevant in understanding the origin of CRD-negative DAF in urine and plasma.

Capacitance-voltage (CV) and current-voltage (I-V) measurements for SiO/sub x/N/sub y/ films are compared with chemical data in order to provide some diagnostic capabilities in relating aberrant electrical characteristics with contaminants incorporated in the insulator film structure. In-process monitoring of film quality (utilizing electrical characteristics and chemical data) is especially critical in very large-scale integration (VLSI) processing control where the films are utilized both as an integral part of specific semiconductor device processing steps or as part of the semiconductor device structure. >

A numerical procedure is developed for proportioning the members of an elastic structure so that one or more of its natural frequencies assume given values and the total structural mass is a minimum. It is assumed that the structure is required to support nonstructural masses and that the vibratory inertia loads due to structural masses must be of appreciable magnitude relative to those generated by nonstructural masses. The principal development is based on a finite element idealization and matrix formulation in which the inertia and stiffness matrices of each structural element are proportional to the mass of the element. Lagrange multipliers are employed to introduce the free vibration equations as constraint conditions.

A numerical procedure is developed for determining the relative proportions of selected elements of an aircraft structure, to attain a specified flutter speed with minimum total mass. The procedure is based on a finite-element idealization of the structure. Lagrange multipliers are employed to introduce the conditions for neutral dynamic stability (flutter equations) as dynamic constraints. The resulting system of nonlinear equations is solved by the Newton-Raphson process to determine the masses of the elements of the system. b [B] [C] [K]

The 1H n.m.r. spectra of a number of derivatives of (–)-quinic acid and quinide are interpreted in terms of the preferred conformations of these molecules. Out of twenty-nine derivatives, thirteen exhibit apparent magnetic equivalence of the C-2 or C-6 protons.

The method of direct formulation of the stiffness matr ix 1 3 is extended to include the effects of nonuniform heating and large deflections. The purpose is to develop an analytical tool for the treatment of actual structures. In the solution of aeroelastic problems the relations between forces and deflections must be determined. The usual stiffness matrix formulation of this relationship is limited to small temperature changes and small deflections. For large temperature changes additional terms are required. Also the problem becomes geometrically nonlinear when large deflections are involved. To overcome the inherent difficulties of the nonlinear problem for practical structures either an iterative or a step-bystep procedure must be used. The force-deformation relations necessary for this step-by-step or iterative approach are derived for an axially loaded member and for a plate element including the effects of thermal strains.

SummarySummaryProstaglandin E2 vaginal tablets proved effective in the management of premature rupture of the membranes at or near term in 100 primigravidae with an unfavourable cervix and no uterine contractions. The caesarean section rate was 7 per cent, the forceps delivery rate 19 per cent, and 74 per cent delivered normally.Once in labour, a policy of active management was followed, and this almost certainly contributed to the low level of surgical intervention.

Antigenic variation in the African trypanosomes involves the sequential expression of genes coding for different variant surface glycoproteins (VSGs) (reviewed in refs 1-3). When expression of some VSG genes is switched on, a newly duplicated copy of the expressed gene has been observed within the trypanosome genome, which is not found after the gene's expression is switched off again. The duplicated copy has therefore been called an expression-linked copy (ELC). The expression of the gene appears to be strictly coupled to the presence of the ELC. This has led to the hypothesis that the duplicative transposition generating the ELC may itself be responsible for the control of VSG expression. With other VSG genes, expression-linked duplication has not been observed, and expression is clearly not controlled in this way. Data are presented here which demonstrate that either of these observations may be obtained with a single VSG gene, depending on the chance selection of particular clones from antigenically switched populations. Thus, the different observations do not imply the existence of two distinct classes of VSG gene controlled by different mechanisms, but different aspects of processes common to all VSG genes.

To evaluate the measurement of fluid status in the premature neonate using dynamic skinfold thickness (DST) measurement, a pair of calipers were interfaced to a computer, and weight and digital DST at four sites were measured daily in 24 neonates in the postnatal weight loss period. A biexponential equation was fitted to each curve from the instant the rate of caliper closure fell below 2 mm/s, and the five constants obtained used in a search for a parameter that correlated with the percentage of weight loss. The percentage of fall in the DST from 0.4 to 30 seconds yielded highest mean of individual coefficients of determination (COD) (0.83); the percentage of fall from 0.7 to 35 seconds yielded highest COD in pooled data (0.56). Expected weight loss can be predicted with standard error of 2.9% with pooled regression but with standard error of 1.3% using individual correlations. We conclude that individuals lose fluid in a consistent manner during this period but that interindividual differences are large and require further investigation.

Most bezoars are composed of hair (trichobezoars) or fibrous food debris (phytobezoars). The great majority are found in the stomach. DeBakey and Ochsner (1938, 1939) list 303 bezoars from the world literature and report another eight cases. Their total of 311 includes 172 trichobezoars, 126 phytobezoars and 13 bezoars of other concretions with only a single case of bezoar confined to the oesophagus. Various individual reports of oesophageal bezoar published since include nine cases of bezoar and two of food impaction (Pelner & Levy 1960; Mersten et al, 1981). They include six males and four females, with ages ranging from 27 to 78. We report an example of an intrathoracic phytobezoar causing acute gastro-oesophageal symptoms. A 50-year-old woman was admitted in 1980 with a threeweek history of vomiting, epigastric pain and weight loss. In 1971 she had undergone surgery for hiatus hernia. She had presented at another hospital in 1977 with epigastric pain and vomiting, when a barium meal had demonstrated w...

Results from a continuing clinical trial in benign breast disease indicate that danazol may induce progesterone receptors and that this effect persists after treatment. In women given danazol the number of biopsy specimens that were positive for progesterone receptors rose from 14 out of 31 before treatment to 23 out of 30 at the end of six months' treatment and remained raised at 21 out of 31 six months later. The number of biopsy specimens that were positive for oestrogen receptors rose transiently from eight out of 31 to 12 out of 30 and then fell to six out of 31. A satisfactory clinical response was achieved in 26 of the 31 patients but was maintained in only 11 six months or more after the end of treatment. It was only in this group that a significant and long-standing increase in progesterone receptors was observed. These findings suggest that in some women with benign breast disease who have been treated with danazol changes occur that may have long term benefit.

SUMMARYVariant antigenic types (VATs) represented in a total of 47 first relapse populations of 6 clones of Trypanosoma brucei LUMP 227 were identified by immunofluorescent staining of living trypanosomes, using antiserum raised against purified surface antigens. The relative growth rates of these 6 clones were measured both individually and when grown together in a mixed population, and were found to be different under these two sets of conditions. A pattern emerged in the VATs represented in relapses of each clone, with some types being expressed more frequently than others and certain VATs being only very rarely expressed. It is suggested that new VATs are expressed according to a statistically definable order of priority which is different for each parent VAT, and that some VATs may be able to change to certain others only after passing through an intermediate VAT. The order of priority of appearance of VATs does not appear to correlate with growth rate measured either in individual clones or when clones are grown in a mixed population.

The inferior vena cava (i.v.c.) is a collapsible vessel which is subject to respiratory pressure variations. Clinical observations on humans show that, during deep inspiration, an increase in the propulsive pressure gradient causes the i.v.c. to collapse near the diaphragm and paradoxically reduces the blood flow. Postmortem casts show that there is a sharply localised elastic constriction where the i.v.c. passes through the diaphragm. A passive mechanical model, incorporating a similar elastic constriction, exhibits similar paradoxical or negative-resistance behaviour, which is in accordance with the principles governing flow through collapsible tubes.

To test the hypothesis that steroid hormone receptor expression is particularly pronounced in breast tumours when compared with non-neoplastic tissue, mastectomy samples were divided into 16 sectors. Multifocal tumours, of varying receptor phenotype were found in 4 patients and in addition different regions of large tumours also showed varying receptor contents. Remaining samples were found to consist of normal tissue, with fat, connective tissue and some benign breast disease. In the 9 patients with oestrogen receptor positive tumours (ER), ER content was invariably much greater in the tumours than in the remainder of the breast. Progesterone receptor (PR) content was not closely related to ER, and was lowest in the poorly differentiated tumours. This relation to differentiation was not seen in ER. The data support the view that ER concentration in ER positive tumours may reflect the transformed nature of neoplastic tissue.

In a previous study the value of conventional tomography was assessed in the diagnosis of 100 potentially malignant opacities on the chest radiograph. To determine which of the radiological signs were most useful the radiologists reviewed 82 of the original 100 radiographs independently, searching for the presence or absence of 36 signs. The five commonest signs of bronchial carcinoma were a mass, coarse linear shadows contiguous to a mass, unilateral hilar enlargement, linear shadows from mass to periphery, and an irregular margin to a mass. The combination of either two or three of these signs was highly sensitive, 95% and 89% respectively, in detecting carcinoma. The most useful specific signs were lobulation of the mass and cavitation with thick or irregular walls.

Electrical stimulation of the nervous system is of increasing importance for a variety of prospective neural prostheses. Electrochemical reactions which may occur at Pt or other noble metal-tissue interfaces are reviewed. Use of stimulus waveforms with a net direct current component increases the probability of tissue damage. There are three conceptually safe methods of injecting charge from a noble metal into tissue: modification of the electrical double layer at the interface and coupling via either of two symmetrical surface-layer oxidation-reduction processes. These reactions may be addressed with stimulus waveforms without a direct current component and with controlled charge densities.

This study examined the contraceptive practices of 100 patients referred for colposcopy because of an abnormal cervical smear. At presentation 49% were using oral contraception but 94% had taken the pill at some time. Eight of the 10 patients using barrier methods were relying on condoms: in at least seven of the eight cases an abnormal cervical smear preceded condom usage. Thus, the method of contraception used when cervical neoplasia develops may differ from the method used when the patient presents for colposcopy. Although consistent with previous studies suggesting that the incidence of cervical neoplasia is increased in women using oral contraception, the risk of neoplasia is more likely to be explained by the degree of exposure of the cervix to an infectious carcinogen or to the immunosuppressive effects of seminal plasma. We suggest that future studies of the epidemiology and natural history of cervical neoplasia should include a detailed contraceptive history.

Placental separation in the third trimester of pregnancy may be associated with coagulopathy, fetal distress, or intrauterine death. We report a case of vaginal bleeding due to placental separation at 17 weeks' gestation associated with disseminated intravascular coagulation. After treatment with blood, fresh frozen plasma, and fibrinogen, the pregnancy progressed uneventfully for another 12 weeks, when delivery by emergency cesarean section was performed.

Three experimental groups of male Glossina morsitans morsitans were infected at their first feed with procyclic forms of different stocks of Trypanosoma congolense and subsequently maintained on a diet containing rabbit antiserum to one of these stocks. Control flies were similarly infected but were then maintained on normal rabbit serum. Dissection of the flies 19-21 days post infection showed a reduction in both immature and mature infection rates in all groups fed on antiserum by comparison with control flies. These results suggest that vaccination with a single procyclic T. congolense strain could reduce transmission of both homologous and heterologous T. congolense strains which might, in certain epidemiological circumstances, provide an alternative or additional control method for African trypanosomiases.