Theoretical z -pinch scaling relations for thermonuclear-fusion experiments

We have developed wire-array z -pinch scaling relations for plasma-physics and inertial-confinement-fusion (ICF) experiments. The relations can be applied to the design of z -pinch accelerators for high-fusion-yield (approximately 0.4 GJ/shot) and inertial-fusion-energy (approximately 3 GJ/shot) research. We find that (delta(a)/delta(RT)) proportional (m/l)1/4 (Rgamma)(-1/2), where delta(a) is the imploding-sheath thickness of a wire-ablation-dominated pinch, delta(RT) is the sheath thickness of a Rayleigh-Taylor-dominated pinch, m is the total wire-array mass, l is the axial length of the array, R is the initial array radius, and gamma is a dimensionless functional of the shape of the current pulse that drives the pinch implosion. When the product Rgamma is held constant the sheath thickness is, at sufficiently large values of m/l, determined primarily by wire ablation. For an ablation-dominated pinch, we estimate that the peak radiated x-ray power P(r) proportional (I/tau(i))(3/2)Rlphigamma, where I is the peak pinch current, tau(i) is the pinch implosion time, and phi is a dimensionless functional of the current-pulse shape. This scaling relation is consistent with experiment when 13 MA < or = I < or = 20 MA, 93 ns < or = tau(i) < or = 169 ns, 10 mm < or = R < or = 20 mm, 10 mm < or = l < or = 20 mm, and 2.0 mg/cm < or = m/l < or = 7.3 mg/cm. Assuming an ablation-dominated pinch and that Rlphigamma is held constant, we find that the x-ray-power efficiency eta(x) congruent to P(r)/P(a) of a coupled pinch-accelerator system is proportional to (tau(i)P(r)(7/9 ))(-1), where P(a) is the peak accelerator power. The pinch current and accelerator power required to achieve a given value of P(r) are proportional to tau(i), and the requisite accelerator energy E(a) is proportional to tau2(i). These results suggest that the performance of an ablation-dominated pinch, and the efficiency of a coupled pinch-accelerator system, can be improved substantially by decreasing the implosion time tau(i). For an accelerator coupled to a double-pinch-driven hohlraum that drives the implosion of an ICF fuel capsule, we find that the accelerator power and energy required to achieve high-yield fusion scale as tau(i)0.36 and tau(i)1.36, respectively. Thus the accelerator requirements decrease as the implosion time is decreased. However, the x-ray-power and thermonuclear-yield efficiencies of such a coupled system increase with tau(i). We also find that increasing the anode-cathode gap of the pinch from 2 to 4 mm increases the requisite values of P(a) and E(a) by as much as a factor of 2.

TcDJ1, a putative mitochondrial DnaJ protein in Trypanosoma cruzi

A full length cDNA encoding a novel Trypanosoma cruzi DnaJ protein was cloned and characterized. The 324 amino acid protein encoded by the cDNA (TcDJ1) displays a characteristics J-domain, but lacks the Gly-Phe and zinc finger regions present in some other DnaJ proteins. Relative to four other T. cruzi DnaJ proteins, TcDJ1 has an amino terminal extension containing basic and hydroxylated resides characteristic of mitochondrial import peptides. A T. cruzi transfectant expressing epitope-tagged TcDJ1 was generated and subcellular fractions were produced. Western blot analysis revealed that the protein has a molecular mass of 29 kDa and is found in the mitochondrial fraction. The expression of TcDJ1 is developmentally regulated since the levels of both mRNA and protein are much higher in epimastigotes (replicative form) than in metacyclic trypomastigotes (infective form). Thus it may participate in mitochondrial biosynthetic processes in this organism.

Clinical outcomes of four patients with microdeletion in the long arm of chromosome 2

We present clinical outcome, through several years of follow-up, of 4 mentally retarded patients, each with a small interstitial deletion in the long arm of chromosome 2, within a region on which clinical reports are infrequent. Our patient 1 was found to have del(2)(q22.3q23.3); patients 2 and 3, del(2)(q23.3q24.2); and patient 4, del(2) (q24.2q31). By comparison of our cases with each other and with those previously published with comparable interstitial deletion, we attempted to identify characteristic clinical findings. Short neck with excessive cervical skin was seen with monosomy of chromosome 2 bands q22.3-q23.3, while hypertrichosis and a peculiar high pitched cry were seen with monosomy of chromosome 2 bands q23.3-q24.2. As suggested by Moller et al. [1984: Hum Genet 68:77-86], a cleft between the first and second toes was seen with monosomy of chromosome 2 bands q24.2-q31. In addition, seizure disorder was present in patients 1 and 4 (with the more proximal and distal deletions, respectively).

The DnaJ family of protein chaperones in Trypanosoma cruzi

We have molecularly cloned four members of the DnaJ (heat shock protein 40) family of protein chaperones of the protozoan parasite Trypanosoma cruzi--tcj1, tcj2, tcj3 and tcj4. While all the proteins contain defining J domains at their N-termini, only tcj2, tcj3 and tcj4 contain glycine/phenylalanine-rich and zinc finger domains common to many other DnaJ homologues. Furthermore, tcj2 and tcj4 contain C-terminal CaaX motifs, substrates for prenyl modifications, suggesting that they are associated with cellular membranes. tcj1 is a divergent member of the family, containing neither glycine/phenylalanine-rich nor zinc finger domains. All the T. cruzi DnaJ genes are single copy, in contrast to other T. cruzi heat shock genes, which are arranged in multicopy direct tandem arrays. Among the tcj mRNAs, only tcj2 is heat inducible, which may result from posttranscriptional regulation involving a sequence found in the 3' untranslated regions of all heat-inducible T. cruzi mRNAs described to date. Further study of this important family of protein chaperones will aid our understanding of the protein folding and assembly processes in protozoans.

Homologues of the 24-kDa flagellar Ca(2+)-binding protein gene of Trypanosoma cruzi are present in other members of the Trypanosomatidae family

A full-length cDNA encoding the 24-kDa flagellar Ca(2+)-binding protein (FCaBP) of the Dm28c clone of Trypanosoma cruzi was cloned and characterized. Comparison of the deduced amino acid sequence with those of the FCaBPs of other T. cruzi strains revealed greater than 97% sequence conservation. FCaBP-like genes are found in Trypanosoma conorhini, Trypanosoma freitasi, Trypanosoma lewisi, Herpetomonas megaseliae, Leptomonas seymouri, and Phytomonas serpens, but not in Crithidia deanei, Leishmania amazonensis, or Endotrypanum schaudinni: Among various T. cruzi strains, FCaBP genes are located on chromosomes of different size, although all strains possess multiple FCaBP genes organized as tandemly arranged gene families. Northern and Western blot analyses revealed that FCaBP mRNAs are produced in all organisms possessing FCaBP-hybridizing sequences, indicating that expression of FCaBP or an FCaBP-like protein is common to a number of trypanosomatid species.

Molecular comparison of the mitochondrial and cytoplasmic hsp70 of Trypanosoma cruzi, Trypanosoma brucei and Leishmania major

We compared the expression and localization of the mitochondrial and cytoplasmic hsp70 of the protozoans Trypanosoma cruzi, Trypanosoma brucei and Leishmania major. The mitochondrial protein is encoded by multiple mRNA in all species, while the cytoplasmic protein is encoded by a single mRNA. In all three species, the mitochondrial hsp70 is concentrated in the kinetoplast, a submitochondrial structure that houses the unusual DNA (kDNA) that characterizes this group of organisms, while the cytoplasmic protein is distributed throughout the cell. These results suggest that, in all kinetoplastid species, mt-hsp70 has a specific function in kDNA biology, possibly in the processes of kDNA replication, RNA editing or kinetoplast structure.

Utility of recombinant flagellar calcium-binding protein for serodiagnosis of Trypanosoma cruzi infection

The protozoan Trypanosoma cruzi is the causative agent of Chagas' disease, a major public health problem in Latin America and of growing concern in the United States as the number of infected immigrants increases. There is currently no testing of U.S. blood products for T. cruzi infection, and the best tests available, although highly sensitive, are not of high enough specificity to be useful for widespread screening of the blood supply in this country. Among the parasite antigens detected by sera of infected humans and mice, those in the range of 24 to 26 kDa are particularly reactive. With an aim of developing a sensitive, specific, recombinant antigen-based serologic test for T. cruzi infection, we used two antibody reagents specific for these 24- to 26-kDa antigens to isolate cDNA clones from a T. cruzi expression library. One clone was found to encode a previously characterized T. cruzi antigen, a 24-kDa flagellar calcium-binding protein (FCaBP). Recombinant FCaBP was found to be a sensitive, specific reagent for distinguishing T. cruzi-infected individuals from uninfected persons, and it therefore could potentially be used for screening purposes, especially if combined with other recombinant T. cruzi antigens that have similarly high degrees of diagnostic sensitivity and specificity.

Comparison of the 24 kDa flagellar calcium-binding protein cDNA of two strains of Trypanosoma cruzi

DNA sequences encoding the 24 kDa flagellar calcium binding protein (FCaBP) of two strains of Trypanosoma cruzi were found to differ at fourteen positions, six of which result in amino acid differences. Four of the amino acid differences are located within the calcium-binding domains of FCaBP; however, none is predicted to affect the calcium-binding ability of the protein. Chromosomes harboring the FCaBP gene clusters differ in size among T. cruzi strains.

Expression and localization of Trypanosoma cruzi hsp60

A 60-kDa heat shock protein (hsp60) is involved in mitochondrial protein folding and assembly of oligomeric protein complexes in the mitochondrial matrix. Here we report the isolation of Trypanosoma cruzi hsp60 cDNAs, the determination of the organization and chromosomal location of the genes, and the assessment of the heat-regulated expression and subcellular location of the protein. T. cruzi hsp60 is encoded by a multigene family organized in two allelic direct tandem arrays on a chromosome of 1.6 Mb. The regulation of hsp60 expression by heat is complex. While the hsp60 mRNA level is 6-fold higher at 37 degrees C than at either 26 degrees C, the hsp60 protein level remains essentially constant across all temperatures examined. Further analysis of the protein by two-dimensional immunoblotting revealed the existence of multiple isoforms that, with increasing temperature, shift in relative abundance from the more basic to the more acidic. A combination of immunofluorescence microscopy and cell fractionation was used to show that hsp60 is distributed throughout the matrix of the mitochondrion--a location distinct from that of the 70-kDa mitochondrial hsp, mtp70, which is associated with the kinetoplast.

Overweight women delay medical care

OBJECTIVE

To determine whether women delay or avoid necessary health care because they are overweight.

DESIGN

Observational study using a self-administered survey.

SETTING

A 250-bed community hospital in La Crosse, Wis.

PARTICIPANTS

All female nurses, nursing assistants, health unit coordinators, and general psychiatric assistants who were employed full- or part-time at the community hospital in July 1992. We received 310 (76%) responses from 409 potential respondents.

MEASUREMENTS/MAIN RESULTS

Overall, 12.7% of respondents reported delaying or canceling a physician appointment because of weight concerns. Another 2.6% kept their appointments but refused to be weighed. Only body mass index was significantly associated with appointment cancellation. The odds ratio of an obese woman (body mass index in excess of 27) delaying medical care was 3.885 (95% confidence interval, 1.509 to 10.274).

CONCLUSION

Obese women commonly delay health care because of weight concerns.

Blistering disorders. Which ones can be deadly?

Blisters are a manifestation of many diseases, which range from the trivial to the life-threatening. Distinguishing between these conditions can be crucial to the patient's well-being. Dr Olson presents an overview of the common causes of blistering, with emphasis on immunobullous diseases, which demand early recognition and prompt treatment.

Molecular cloning and characterization of the 78-kilodalton glucose-regulated protein of Trypanosoma cruzi

The protozoan Trypanosoma cruzi is the etiologic agent of Chagas' disease, an illness responsible for morbidity and death among millions of Latin Americans. Mice also develop this disease when infected with T. cruzi and are a useful model organism for the study of parasite-specific immune responses. To identify immunogenic T. cruzi antigens, serum from an infected mouse was used to isolate clones from a T. cruzi epimastigote cDNA expression library. One of these clones was found to encode the 78-kDa glucose-regulated protein (grp78), the endoplasmic reticular member of the 70-kDa heat shock protein (hsp70) family. Like the mammalian and yeast grp78s, the T. cruzi protein contains an endoplasmic reticular leader peptide and a carboxyl-terminal endoplasmic reticular retention sequence. T. cruzi grp78 is encoded by a tandemly arranged family of three genes located on a chromosome of 1.6 Mb. The effects on grp78 expression of heat shock and tunicamycin treatment, the latter of which specifically stimulates mammalian grp78, were investigated. While the level of the grp78 protein remained constant under all circumstances, grp78 mRNA was unaffected by heat shock but induced fivefold by tunicamycin. Finally, we found that grp78 is the most immunogenic of the T. cruzi heat shock proteins we have characterized, reacting strongly in immunoblots with sera from infected mice.

Molecular and biochemical comparison of the 70-kDa heat shock proteins of Trypanosoma cruzi

An analysis of the genetic organization, regulated expression and biochemical properties of the cytoplasmic/nuclear (hsp70) and mitochondrial (mtp70) 70-kDa heat shock proteins of Trypanosoma cruzi is presented. The two proteins are encoded by tandemly arranged gene families that are located on different chromosomes. Both are mildly heat-inducible but have different optimal temperatures for expression. During the switch from proliferation to differentiation that occurs during the growth of T. cruzi in culture, the hsp70 level decreases dramatically while the mtp70 level falls only slightly. The subcellular locations of the two proteins differ during heat shock. While mtp70 remains associated with the kinetoplast at all temperatures, hsp70 becomes more concentrated in the nucleus at higher temperatures. Biochemical analysis of hsp70 and mtp70 revealed both to be potent ATPases. Each protein binds ATP with a Km of about 70 microM and hydrolyzes ATP with a kcat of about 100 min-1, 100 times greater than the kcat of human hsp70. The high ATPase activities of hsp70 and mtp70 are further stimulated by incubation with peptides, suggesting that these trypanosome heat shock proteins have protein chaperone activity. Finally, mtp70, but not hsp70, was found to possess autophosphorylation activity in vitro, a property that it shares with prokaryotic hsp70. These findings demonstrate unique cellular and biochemical characteristics of T. cruzi mtp70 and hsp70 that suggest that they play distinct physiologic roles in the biology of the cell.

Intrapartum intervention and delivery outcome in low-risk pregnancy

A retrospective cohort study of 1597 low-risk pregnancies assessed the effects of obstetrical intervention using logistic regression. Both maternal and neonatal morbidity were low (15.2 percent and 3.8 percent, respectively). Epidural analgesia, oxytocin, or both, were associated with worse maternal outcome, and neonatal outcome was worse when oxytocin was used. However, epidural analgesia seemed to provide a protective neonatal effect when oxytocin was used during labor. Both elective and medically necessary use of these interventions were associated with increased morbidity. If obstetrical interventions, particularly oxytocin and epidural analgesia, are applied in low-risk pregnancies, labors must be monitored carefully and the risk-benefit ratios judged advantageous.

Identification and localization of major cortical proteins in the ciliated protozoan, Euplotes eurystomus

Shape-preserving cortical residues have been isolated from Euplotes eurystomus cells by the application of Triton X-100 at high ionic strength. These integrated structures consist of articulated plates and widely interspersed cages that formerly contained basal bodies associated with the clusters of cilia characteristic of this cell type. Using SDS-PAGE and immunolocalization procedures, we have identified major subunit proteins of both the plates (116, 110 (X10(3] Mr, and the basal body cages (86 X 10(3) Mr). The potential for studies of these proteins in contributing to our understanding of cortical development and evolution in Euplotes is discussed.

Computed tomographic measurement of cortical bone geometry

In this study digital images of bone cross-sections obtained by computed tomography were analyzed with an automated outlining method. It was shown that unbiased cross-sectional geometric measurements of cortical bone could be obtained if the periosteal and endosteal surfaces were defined at separate thresholds. Use of different threshold levels for these two surfaces resulted in errors of 2.6% for periosteal diameters, 7.4% for endosteal diameters and 7.3% for cortical area. If incorrect thresholds were used, cortical thickness measurements can have errors as high as 30%. In addition, simulated variation in medullary fat content did not affect measurement of medullary dimensions.

Naloxone in renal ischemia: a functional and microanatomical study

Naloxone HCl (Nx) improves cardiopulmonary performance, reverses cellular hypoxia, and stabilizes lysosomal membranes in shock states. However, no detailed study has yet explored its potential role in renal ischemia, which is inevitable in transplantation and surgical and nonsurgical conditions associated with hypotension and shock. This functional and microanatomical study was carried out on dogs subjected to renal warm ischemia with contralateral nephrectomy. Group I (control; N = 4) had bilateral renal dissection and right nephrectomy. Groups II-IV had their kidney pedicles cross-clamped for 60 min and then reperfused. Group II (N = 9) ischemic kidneys received no treatment. Group III (N = 6) kidneys were flushed with pure Nx HCl (2 mg/kg) during ischemia. Group IV (N = 6) dogs received one iv Nx bolus (2 mg/kg) before clamping and another dose before declamping. Biopsies for adenine nucleotides, histology, and ultrastructure were obtained before ischemia, before reflow, and 15 min and 7 days after reflow. Serum creatinine and blood urea nitrogen were measured daily. Ischemia induced significant renal dysfunction, which was reversed by systemic Nx. Nx offered a remarkable protection against postischemic structural damage. Seventy percent of Group II cortical sections showed grade 4 acute tubular necrosis (ATN), and severe residual damage after a week. Eighty-three percent of Group IV sections showed grade 1 ATN and no residual damage after a week. One week survival was 33% in Group II and 100% in Group IV. Nx can be useful in prevention of acute renal failure in clinical situations with arterial hypotension and shock.

Periodontal bone loss and immune characteristics of congenitally athymic and thymus cell-reconstituted athymic rats

We investigated the ability to reconstitute the T-cell deficiency in congenitally athymic (nude; rnu/rnu) Rowett rats by intravenous injection of 10(7) heterozygous normal (rnu/+) rat thymus cells. The thymus cell-reconstituted animals showed essentially normal lymphocyte proliferation to phytohemagglutinin P and concanavalin A, normal spleen and lymph node T-lymphocyte distribution, and normal serum immunoglobulin G levels. These rats were used to study the effect of T-cell deficiency on periodontal disease. Animals with minimal oral flora were divided into three groups: nude, thymus cell-reconstituted nude, and normal rats. Immune response, gingival inflammation, and periodontal bone loss were examined in these animals. Less than 40% of the T cells recovered from the normal rat gingiva could be recovered from the nude rat gingiva. In contrast to the situation in normal or thymus cell-reconstituted rat gingiva, B cells were vastly predominant in the nude rat gingiva, with approximately four B cells for each T cell. There was increased periodontal bone loss in the nude rats compared with that in the normal rats. Thymus cell reconstitution of the nude rats was associated with decreased bone destruction. It is suggested that T cells have a regulatory function in relation to the potentially excessive B-cell response to abundant antigen and polyclonal activators in the oral cavity.

Activation of rat B lymphocytes by Actinobacillus actinomycetemcomitans

We examined the lymphoproliferative responses of cervical lymphocytes and splenocytes of homozygous (rnu/rnu) congenitally athymic nude and normal heterozygous (rnu/+) Rowett rats to whole cells of Actinobacillus actinomycetemcomitans, a suspected periodontal disease pathogen. Previously sensitized cells from immunized only, infected only, or immunized and infected, normal rats demonstrated proliferation in response to formalinized A. actinomycetemcomitans, but cells from nude rats did not proliferate. The maximum antigenic response was observed at day 5 of culture. A. actinomycetemcomitans caused cervical lymphocytes and splenocytes from untreated naive normal and nude rats to undergo increased DNA synthesis at day 2 of culture. Highly enriched nonsensitized spleen T cells prepared on a nylon wool column did not respond to A. actinomycetemcomitans, whereas enriched nonsensitized B cells proliferated. Differences in response were probably not attributable to contributions from macrophages in the T- or B-cell populations, since macrophage percentages were approximately the same in both preparations. T-cell reconstitution of nude rats with neonatal thymus cells from rnu/+rats resulted in partial recovery of T-cell function but had no effect on the mitogenic response to A. actinomycetemcomitans. It is suggested that the antigenic responses to A. actinomycetemcomitans are dependent on T cells and that A. actinomycetemcomitans cells have mitogenic activity for B cells. The potential importance of these findings in periodontal disease is discussed.

Host response in experimental periodontal disease

Experiments were performed to determine the role of the immune response in rat periodontal disease. Germ-free rats were fed defined antigen-free liquid diets or a diet containing ovalbumin(OVA) as a prototype antigen. The OVA-fed rats demonstrated increased gingival lymphocytes (mainly T at early times), OVA-sensitized spleen cells, and increased periodontal bone loss. In further studies, rats pre-sensitized with OVA, and receiving OVA in the diet, showed elevated IgG antibody, sensitized spleen cells, and elevated periodontal bone loss scores. The concept that bone loss was due to mixed hypersensitivity reaction is consistent with the periodontal pathology. The effects of pre-immunization with A. actinomycetemcomitans (Aa) on periodontal bone loss in Actinobacillus (Aa) - infected rats was examined. Delayed hypersensitivity (DTH) was present in immunized rats throughout the experimental period. Sham-immunized rats showed DTH after 30 days of infection. In addition, immunized rats showed elevated bone loss scores. These experiments support the contention that a combination of hypersensitivity reactions (i.e., mixed hypersensitivity to Aa) could give rise to the periodontal pathology observed. Congenitally athymic rats (nude) were shown to have more periodontal bone loss than did normal littermates. However, bone loss in thymus-cell reconstituted nude rats was not different from that in control rats. Normal rats receiving Aa-sensitized T lymphocytes prior to infection with Aa demonstrated increased DTH and periodontal bone loss. These studies support the concept that T-cell functions and thymic regulation of immune responses can exert protective and/or destructive effects in periodontal disease. In order to modify disease, it will be necessary to enhance the protective aspects of the immune response and to minimize the detrimental aspects.

Development of a multichannel electrochemical centrifugal analyzer

A new instrument has been developed that is similar in design and concept to the GeMSAEC centrifugal analyzer (Oak Ridge National Laboratory) except that electrochemical detection is used rather than optical detection. The present version has eight channels, each with its own detector. Problems of speed control and sampling synchronization are greatly minimized from those of a multichannel centrifugal analyzer having a single detector system. All eight sample compartments and polarographic cells are contained in a single Teflon rotor, 7.7 cm in diameter. The working electrodes are planar carbon electrodes. The initial application of the analyzer is in kinetic methods involving the rates of enzyme-catalyzed reactions. The initial system chosen was the glucose oxidase system. When the rotor is spun, the solution moves into the sample cell and up against the planar working electrode. The reaction starts and current is measured as a function of time at a constant applied voltage. The current output from each polarographic circuit is connected to a separate channel of a multiplexed analog-to-digital converter. The analyzer is controlled by a dedicated microcomputer system, which sets the polarographic cell voltages, collects the current-time data, and calculates the results.

Development of a multichannel electrochemical centrifugal analyzer

A new instrument has been developed that is similar in design and concept to the GeMSAEC centrifugal analyzer (Oak Ridge National Laboratory) except that electrochemical detection is used rather than optical detection. The present version has eight channels, each with its own detector. Problems of speed control and sampling synchronization are greatly minimized from those of a multichannel centrifugal analyzer having a single detector system. All eight sample compartments and polarographic cells are contained in a single Teflon rotor, 7.7 cm in diameter. The working electrodes are planar carbon electrodes. The initial application of the analyzer is in kinetic methods involving the rates of enzyme-catalyzed reactions. The initial system chosen was the glucose oxidase system. When the rotor is spun, the solution moves into the sample cell and up against the planar working electrode. The reaction starts and current is measured as a function of time at a constant applied voltage. The current output from each polarographic circuit is connected to a separate channel of a multiplexed analog-to-digital converter. The analyzer is controlled by a dedicated microcomputer system, which sets the polarographic cell voltages, collects the current-time data, and calculates the results.

Sarcoidosis with optic nerve and retinal involvement

A patient with the typical funduscopic changes of sarcoidosis died following an accident. The histopathological findings in one eye were correlated with the ophthalmoscopic observations made several days prior to death. Gross and histopathological examination revealed that the characteristic whitish-yellow focal retinal exudates, the perivascular exudates with an appearance like candle wax drippings, the preretinal and intravitreal nodules, and the localized tumefactions on the inner surface of the retina and optic nerve head noted ophthalmoscopically were a result of the nodular proliferation of epithelioid cells. These cells appeared to be derived primarily from blood vessels in the retina and optic nerve head. Although subpigment epithelial granulomas were found, there were no granulomas present within the choroid or elsewhere within the uvea.