Modified method of vascular repair with autologous fascia and synthetic adhesive: an animal experiment

Subsequent to arteriotomy of the common carotid artery on both sides in rats, the right common carotid was repaired by microvascular suture, and the left with autologous fascia and synthetic adhesive; the results of both types of repair were compared. The rats were sacrificed at weekly intervals for up to two months, and the arteries were examined for patency and histopathologic changes. The initial inflammation and wound healing were similar in both types of repair. Vessels repaired by fascia and adhesive had a prolonged period of perivascular inflammation and formation of a microcyst containing crystallized adhesive. After two months, the vessels were grossly normal showing only mild perivascular inflammation and residual microcysts. Microvascular suture was followed by medial displacement and fibrosis of the wall, resulting in marked narrowing of the lumen after two months. In our series, the results of repair with fascia and adhesive were considered satisfactory, and the pathologic changes were less severe than those reported in the literature. This could be ascribed to the use of a minimal amount of adhesive and of covering the vasculotomy opening with fascia before applying the adhesive so as to avoid contact between the adhesive and the cut edges of the vessel wall. This modified technique may be considered in the repair of intracranial vessels in emergency situations when microvascular suture is difficult or impossible.

Cell cycle control of polyomavirus-induced transformation

The cell cycle dependence of polyomavirus transformation was analyzed in infections of nonpermissive Fischer rat (FR3T3) cells released from G0. A 5- to 100-fold (average, ca. 20-fold) difference in relative frequency of transformation was found for cells infected in the early G1 phase of the cell cycle compared with cells infected in G2. Differences in the relative level of early viral gene expression in those two cell populations were equivalent to those obtained for transformation frequencies. The difference in transformation potential was accounted for only in part by a cell cycle control of viral adsorption (2- to 15-fold effect). Furthermore, in cells infected in the early G1 phase, viral gene expression was induced as a big synchronous burst of large transcripts of variable sizes, delayed till the G1 phase of the cell cycle after that in which infection took place. Thus, the results demonstrate that the abortive infection cycle of G0-released FR3T3 cells is cell cycle regulated at least at two steps: adsorption and another early step, nuclear transport, decapsidation, up to or including the transcription of the viral early genes. The cell cycle regulation of these steps results in a similar regulation of the abortive and stable transformation processes, although it is more pronounced for the latter. A model implicating c-fos and c-jun is proposed.

[Congenital CSF otitic leakage presenting as rhinorrhea: report of a case]

A 10-year-old girl was brought to our ear, nose and throat clinic for consultation on her articulation problem in addition to an attack of bacterial meningitis and cerebrospinal fluid (CSF) rhinorrhea. These problems had bothered her and her family for about 5 years. In August 1988, she had received a bifrontal osteoplastic craniotomy for her CSF leakage, but the procedure was ineffective. Local examination showed bilaterally intact ear drums. The left ear drum looked cloudy and thick with poor mobility under pneumatoscopy. A tympanogram showed that B type. Pure tone audiometry revealed a profound sensorineural hearing loss in the left ear. A CT scan showed widening of the internal auditory canal and dysplasia of the left cochlea and vestibule in addition to fluid accumulation in the mastoid and mesotympanum. Under the impression of CSF otorrhea, an exploratory tympanotomy was performed, revealing an area of leakage in the tympanic cavity. It was sealed with abdominal fat, temporal connective tissue and tissue glue. All of the bothersome symptoms disappeared postoperatively during an 18-month follow-up.

Design and construction of a linear shear stress flow chamber

A new parallel plate flow chamber that has a linear variation of shear stress, starting from a predetermined maximum value at the entrance and falling to zero at the exit, has been designed and tested. This is in contrast to the usual rectangular channel plan which produces a constant shear stress over the entire length. The new design is based on the theory of Hele-Shaw flow between parallel plates. To verify the efficacy of the flow channel, the effect of fluid shear stress on platelet adhesion to a fibrinogen-coated glass surface was tested. The percentage of attached platelets after 5 min of shear stress is shown to be a function of shear stress. With this new flow chamber, cell-cell interactions can be studied efficiently over a wide range of shear stress using a single run at constant discharge.

Expression of rat liver NAD(P)H:quinone-acceptor oxidoreductase in Escherichia coli and mutagenesis in vitro at Arg-177

A prokaryotic expression plasmid, pKK-DT2, containing the cDNA of rat liver NAD(P)H:quinone-acceptor oxidoreductase (EC 1.6.99.2; DT-diaphorase) was constructed and used to transform Escherichia coli strain JM109. The rat liver quinone reductase was expressed in strain in JM109 and was inducible with isopropyl beta-D-thiogalactopyranoside (IPTG). The expressed rat protein was purified by affinity chromatography and had kinetic and physical properties identical with the protein purified from rat liver in that it could utilize either NADH or NADPH as the electron donor and its activity was inhibited by dicoumarol. In addition, we have generated four mutants, Arg-177----His (R177H), Arg-177----Ala (R177A), Arg-177----Cys (R177C) and Arg-177----Leu (R177L), using this expression system. Several of the mutants behaved anomalously on SDS/PAGE, but all of the mutant proteins had the expected M(r) as determined by electrospray m.s. These results and those obtained from enzyme kinetic analysis, u.v./visible absorption spectral analysis, and flavin and tryptophan fluorescence analysis of the wild-type enzyme and four mutants indicated that mutations at Arg-177 changed the conformation of the enzyme, resulting in a decrease in enzyme activity. Replacing Arg-177 with leucine altered the protein conformation and decreased FAD incorporation.

Epidemiology of isolated systolic hypertension in Pu-Li, Taiwan

The clinical significance of isolated systolic hypertension (systolic blood pressure greater than or equal to 160 mmHg and diastolic blood pressure less than 90 mmHg) has long been recognized, but its prevalence and correlates have not been well characterized. A community-based study was carried out by the Yang-Ming Crusade in 1987-1988 in Pu-Li Town, Taiwan. Of the 2573 registered residents over 30 years old, 1738 were interviewed, and their fasting blood samples were drawn and tested. The prevalence of isolated systolic hypertension was 2.1%. Age-specific prevalence increased with age. No significant difference was found between men and women. No trend was found at the urbanizational level. To study the significant correlates of isolated systolic hypertension, univariate analyses were applied first. Stratified analyses by age and by sex were used for interaction assessment. Based on the above findings as well as from the clinical point of view, logistic regression was used for multivariate analyses. Logistic regression analysis showed that after controlling the covariates simultaneously, four variables were significantly correlated with isolated systolic hypertension: age (greater than or equal to 50 vs. less than 50 years, OR = 3.4, 95% CI = 1.6-7.2); diabetes (yes vs. no, OR = 2.4, 95% CI = 1.2-4.7); blood urea nitrogen (greater than or equal to 25 vs. less than 25 mg/dl, OR = 2.1, 95% CI = 1.2-3.9); and physical activity (frequent vs. infrequent, OR = 1.8, 95% CI = 1.0-3.1). In comparison with definite (greater than or equal than 160/95 mmHg) and borderline (140/90-160/95 mmHg) hypertension as defined by WHO, the different sets of predictors and the possible adverse effect of frequent physical activity on isolated systolic hypertension were found and discussed.

Spontaneous spinal epidural hematoma: report of seven cases

From July 1984 to June 1990, seven cases of spontaneous spinal epidural hematoma (SSEH) were studied. The common clinical pictures in these cases were rather typical with an apoplectic onset of severe spinal pain followed in hours (median: four hours) by signs of progressive spinal cord compression. All cases underwent myelography and computed tomographic (CT)-myelographic studies which showed in all cases a block by a posterior extradural lesion in the spinal column; however, the correct diagnosis of SSEH was made preoperatively in only three cases. The neurologic deficits prior to surgery were complete or nearly complete paraplegia in five cases and a high grade of paraparesis in the other two. The median interval of paralysis or paresis before surgery was 28 hours. The final outcome was evaluated by the grade of functional recovery, and the following were found to be the favorable factors: 1) incomplete preoperative neurologic deficits; 2) a slow course of clinical progression, especially a long duration of pain before the onset of paralysis; 3) no delay in surgery; 4) involvement of short spinal segments; and 5) lumbosacral lesions. Particular emphasis is made on early diagnosis and prompt surgery for a favorable outcome.

Community-based epidemiological study on diabetes in Pu-Li, Taiwan

OBJECTIVE

To determine the prevalence and possible risk factors associated with diabetes in Pu-Li, Taiwan.

RESEARCH DESIGN AND METHODS

The project was a community-based cross-sectional study with stratified cluster sampling of residents greater than or equal to 30 yr of age. Medical students conducted home-visit interviews with public health nurses, drew fasting blood samples from 1738 of 2573 registered residents greater than or equal to 30 yr of age in Pu-Li, Taiwan.

RESULTS

The prevalence of diabetes, including those with a history of diabetes and newly diagnosed cases determined by modified World Health Organization criteria, was 12.4%. With the standard world population of Segi, the age-adjusted prevalences were 6.9% for previous diabetes and 4.4% for new diabetes. The age-specific prevalence of diabetes increased significantly with age for new diabetes cases but not for previously diagnosed cases. To study factors associated with diabetes, we first applied univariate analysis. Stratified analyses by age and sex were used for interaction assessment. A significant interaction effect on diabetes was found between age and sex. Logistic regression was used for multivariate analysis. The final model showed that, after controlling for all other covariates, the significant factors associated with diabetes were family history of diabetes (father and/or mother, yes vs. no, odds ratio [OR] 3.13, 95% confidence interval [CI] 1.17-8.33), obesity (yes vs. no, OR 2.69, 95% CI 1.09-6.63), and age (continuous, OR 1.04, 95% CI 1.00-1.08). Locality and physical activity were not significantly correlated with diabetes.

CONCLUSIONS

The age-adjusted prevalence of diabetes in Pu-Li were 6.9% for previous diabetes and 4.4% for new diabetes. Possible risk factors associated with diabetes with logistic regression were family history of diabetes, obesity, and age. Locality and physical activity were not significantly correlated with diabetes.

Effects of randomly varying birefringence on soliton interactions in optical fibers

The effects of randomly varying birefringence on soliton interactions in optical fibers are studied. It is shown that for initial separations of less than 10 pulse widths, the phase-dependent short-range interaction dominates. For separations larger than 10 pulse widths, the soliton interacts through the dispersive radiation that they generate. This interaction is too weak to explain the phase-independent long-range soliton interaction observed experimentally.

Soft tissue chondroma: case report

Soft tissue chondromas are relatively rare benign tumors, while as osseous chondromas are more commonly found. Although these tumors resemble many other soft tissue lesions, they can usually be differentiated. A review of literature is presented, and clinical manifestations and roentgenographic features are also discussed. An important point to note is that this tumor is benign and spares the patient unnecessary radical therapy.

The flexibility of A-form DNA

We have determined the rise per base pair and persistence length of A-form DNA in trifluoroethanol solutions for fragments 350-900 base pairs in length that best describe rotational diffusion coefficients determined by transient electric birefringence. The 2.6 A spacing between base pairs found in crystal and fiber A-form structures is preserved in solution. The persistence length is about 1500 A, or about three times longer than for B-form DNA. There is no apparent electrostatic contribution to the persistence length in the salt concentration range 0.2-2.0 mM Na cacodylate. This suggests an even closer association between DNA and its neutralizing counterions than predicted by condensation theory, perhaps due to a sheath of trifluoroethanol excluded water surrounding the A-form helix.

[Proptosis and optic nerve compression caused by unilateral ethmoidal pyocele: a case report]

This paper presents the case of a 29 year-old male with a left ethmoidal pyocele with orbital and intracranial extensions causing proptosis and a temporal visual field defect of the left eye. The patient had a history of nasal injury as a result of traffic accident eleven years ago, and was well until four months prior to his first visit at which time he had an onset of left eye pain, proptosis, and blurring of vision developed following a URI episode. Since then, fluctuation of symptoms was noted with exacerbation when contracting a common cold. The left ethmoidal pyocele was diagnosed via clinical features and roentgenographic findings. The patient received a Caldwell Luc Operation with endonasal ethmoidectomy and the postoperative condition was good except for constriction of the entire visual field and the depression of temporal internal isopters of the left eye.

Stability of solitons in randomly varying birefringent fibers

The effects of randomly varying birefringence on solitons are studied. It is shown analytically that the evolution equation can be reduced to the nonlinear Schrödinger equation if the variation length is much shorter than the soliton period. The soliton does not split at high values of the average birefringence, but it does undergo spreading and loss of polarization. A soliton with a temporally constant initial state of polarization is still largely polarized after 40z(0) if the normalized birefringence is delta </= 1.3.

Biochemical and pharmacological development of steroidal inhibitors of aromatase

Androstenedione analogs containing 7 alpha-substituents have proven to be potent inhibitors of aromatase both in vitro and in vivo. Several of these agents have exhibited higher affinity for the enzyme complex than the substrate. In order to examine further the interaction(s) of 7-substituted steroids with aromatase, biochemical and pharmacological studies were performed on 7 alpha-thiosubstituted androstenediones and 7-substituted 4,6-androstadiene-3,17-diones. Potent inhibition of aromatase activity in human placental microsomes has been observed with several new 7 alpha-thiosubstituted androstenediones. 7-Benzyl- and 7-phenethyl-4,6-androstadiene-3,17-diones effectively inhibited microsomal aromatase, with apparent Kis ranging from 61 to 174 nM. On the other hand, 7-phenyl-4,6-androstadiene-3,17-dione exhibited poor activity, with an apparent Ki of 1.42 microM. Similar inhibitory activity was observed with reconstituted, purified cytochrome P450Arom preparations. Additionally, these agents were evaluated for inhibition of aromatase activity in two human carcinoma cell lines, the MCF-7 human mammary cancer line and the JAr choriocarcinoma line. The 7 alpha-thiosubstituted androstenediones and 7-substituted 4,6-androstadiene-3,17-diones produced dose-dependent inhibitions of aromatase activity in the cell cultures. The most effective inhibitors were the 7 alpha-substituted androstenediones, with EC50 values ranging from 7.3 to 105 nM. Finally, the JAr cell culture system exhibited prolonged inhibition of aromatase activity following exposure to 7 alpha-APTADD, suggesting enzyme inactivation by this inhibitor. Thus, these agents are effective aromatase inhibitors, and the results encourage further development of this group of medicinal agents for the treatment of estrogen-dependent mammary carcinoma.

A retrospective study on diagnosis and treatment of severe acute pancreatitis

Severe acute pancreatitis is highly controversial on its diagnostic criteria, the optimum time for surgery, the selection of surgical procedures, and the prevention and treatment of complications. We treated 40 patients with severe acute pancreatitis from July 1983 to July 1988. The comparison of clinical and laboratory data of severe acute pancreatitis and mild acute pancreatitis showed that in some patients neither Ranson's nor Bank's criteria are reliable in classifying or predicting the severity of the disease. The coexistence of acute peritonitis and bloody ascites with elevated amylase level is very helpful to identify the local conditions of pancreatic necrosis and hemorrhage. We suggest early operation (within 48 hours) be applied in severe acute pancreatitis. In our series, five types of surgical procedures were used. We consider that proper treatment of acute respiratory distress syndrome (ARDS) is most important in the management of severe pancreatitis.

[Evaluation of compensator used in radiation therapy]

A radiation beam incident on an irregular or sloping surface produces skewing of isodose curves and may give rise to unacceptable nonuniformity of the dose distribution within the target volume or cause excessive irradiation of sensitive tissues. The concept of using a compensator, first introduced by Ellis, to circumvent the skewness of isodose curves was elegant. Other workers followed suit elaborating further and extending the procedures. The treatment of chest wall tumors is of special interest and compensators were frequently used in their management. The compensators of aluminum and copper were systematically examined for 6 and 10 MV X-rays. Compensating thickness ratios was determined from equivalent dose measurement at compensating depth by placing compensator at the regular blocking tray for maintaining the skin sparing feature of high energy photon beams. The compensator must compensate not only for the reduction of the primary beam attenuation due to tissue deficit, but also for the loss of scattering by the missing tissues. It was found that the compensating thickness ratios (CTR) was not a constant value and was dependent on the tissue deficit, field size, compensating depth and the material of compensator, but was independent of the energy. As the tissue deficit is increased, the CTR decreases, since the loss of scattering for the deficit volume can be compensated by the lowered attenuation of the compensator. As the field size is increased, the CTR decreases. From the study of central axis depth dose for various deficit thickness, normalized at the median plane of no tissue deficit, it was found that compensator can compensate the dose accurately to one depth only and the compensation to other depth is approximate, and that the compensating error is increased with greater tissue deficit and further depth. The effectiveness of the compensating system with a stair-step polystyrene phantom representative of varying tissue deficits over a small treatment field (20 cm x 20 cm) was also studied with film dosimetry and the error was within 3%. The compensator thickness ratios must be measured in different radiation beams from different treatment machines and in different irradiation conditions because there are major difference between the CTR data obtained directly from experiments and the data besed on calculation from attenuation coefficient mu, physical density rho or electronic density, rho e. The specific CTR reported for aluminum and copper in the literature should only be used as a guideline.

Synthesis and biochemistry of fluorescent aromatase inhibitors

Effective aromatase inhibitors have been developed that contain aryl functionalities at the 7 alpha-position of the steroid nucleus. The exact interactions of 7 alpha-substituted androstenediones with the active site of aromatase is unknown. Fluorescent derivatives may provide a useful spectroscopic method for examining the binding of these inhibitors to the microsomal complex and purified aromatase protein. Dinitrophenyl, dansyl, and naphthyl derivatives of 7 alpha-(4'-amino)phenylthio-4-androstene-3,17-dione and androstenedione were synthesized as potential fluorescent agents. An in vitro assay with human placental microsomes was used to evaluate aromatase inhibitory properties. These fluorescent compounds were effective competitive inhibitors and have apparent Ki values ranging from 24.1 to 86.7 nM.

[Effect of eye shielding block position on dose to lens during radiation therapy]

The lens of the eye is very sensitive to radiation and a low dose of radiation may induce cataracts a few years after radiation therapy. In treatment of head and neck tumors, such as cancer of the ethmoid or maxillary sinus, an adequate eye shielding block is mandatory for reducing the lens dose in order to prevent cataract formation. Experiments were designed to simulate the setup of the lens during radiation therapy and it was observed that the dose to the lens was correlated with the distance between the eye shielding block and the eye surface for Co-60, 10MV and 6MV X-rays. With properly fabricated divergent blocks, the optimal shielding points were found to be 6 cm, 0.9 cm and 1.4 cm above the eye surface for Co-60, 10MV and 6MV X-rays, respectively. In a 10 x 10 cm2 field, by moving the eye shielding block on the blocking tray to the optimal shielding point near the surface, the dose to the lens can be reduced from 14% to 8% for Co-60 beams and from 17% to 7% for 10MV and 6MV X-rays. This effect is more evident in larger field sizes. We recommend that the eye shielding block be placed at the optimal shielding point to minimize the dose to the lens. If the eye shielding block cannot be placed at the optimal shielding point, a simple coin placed on the eye lid surface will also reduce the lens dose substantially when a regular eye shielding block is placed on the blocking tray (Lin's coin effect).

[A community-based study on risk factors of hypertension in Luh-Guu Township]

This is a community-based study on hypertension conducted in 1987 to assess the risk of demographic factors and life style of inhabitants aged over 30 in Luh-Guu Township. One-stage cluster sampling was applied. Through home visit interview, the height, weight, and blood pressure as well as demographic and life style data were taken, and 1171 (57.4%) valid data were completed. Hypertension was defined by American National Heart, Lung, Blood Institute as BP greater than = 140/90mmHg. The prevalence of hypertension was 29.2% (the prevalence was 13.4% if defined by the WHO criteria), and only 27.4% of those hypertensives were self-aware. Univariate analysis found that age, educational level, marital status, job condition, smoking habit, father's hypertension history, and usage of contraceptive were correlated with hypertension. With obesity index in addition to the above 6 factors, except contraceptive usage, as independent variables, the multiple logistic regression analysis showed that, only age and obesity index were significantly correlated with hypertension and the best model were fitted.

Needle localization of nonpalpable breast lesions with a portable dual-grid compression system. Work in progress

A new device and a geometric algorithm facilitate consistent insertion of a needle tip into nonpalpable breast lesions on a single attempt. With the breast compressed by dual grid plates, two oblique exposures are taken. Three intersecting planes through the lesion referenced to the grid markings permit easy determination of the lesion coordinates. In initial trials for preoperative breast lesion localization in 11 patients, the needle tip was within the lesion in nine patients and was within 0.5 cm of the lesion in two patients. The results indicate that this system is very useful for accurate localization and needle aspiration of breast lesions.

Flexion teardrop fracture of the cervical spine: radiographic characteristics

Teardrop fracture of the cervical spine is a confusing and loosely used term, often referring to any fracture with a triangular fragment in the involved body. The flexion teardrop fracture is a specific entity that should not be confused with other types of injury with a teardrop fragment. In a radiographic analysis of 45 patients with flexion teardrop fracture, the most characteristic feature was posterior displacement of the upper column of the divided cervical spine, observed in 78% of the cases. Other radiographic characteristics included backward displacement of the posterior fragment of the involved body, widening of the interlaminar and interspinous spaces, widening of the facet joint with backward displacement of the inferior facet, and kyphotic deformity of the cervical spine at the level of injury. The injury was frequently associated with sagittal-body and laminar fractures and occurred predominantly at the C5 level.

Acyl-acyl-carrier protein: lysomonogalactosyldiacylglycerol acyltransferase from the cyanobacterium Anabaena variabilis

Membranes isolated from the cyanobacterium, Anabaena variabilis, and washed free of soluble endogenous constituents, were capable of catalyzing the direct transfer of the acyl group from acyl-acyl-carrier protein to an endogenous lysomonogalactosyldiacylglycerol to form monogalactosyldiacylglycerol. Other glycolipids including monoglucosyldiacylglycerol and digalactosyldiacylglycerol were not products of this reaction. The transfer was not dependent on any added cofactors. Palmitoyl-, stearoyl- and oleoyl-acyl-carrier protein were approximately equally active as substrates. Transfer was exclusively to the C-1 of the glycerol, as demonstrated by hydrolysis of all incorporated acyl groups by the lipase from Rhizopus arrhizus delamar. In addition to the single galactolipid, a second minor reaction product was free fatty acid, presumably due to hydrolysis of the acyl-acyl-carrier protein. Using a double-labelled [14C]acyl-[14C]acyl-carrier protein, the reaction was demonstrated to be a transfer reaction, rather than a simple exchange of acyl groups with endogenous monogalactosyldiacylglycerol. The transfer reaction mechanism was also confirmed by increasing activity with the addition of liposomes of lysomonogalactosyldiacylglycerol.

Non-Hodgkin lymphoma of ureteral wall: CT findings

We report a case of focal ureteral wall non-Hodgkin lymphoma without contiguous or other associated abdominal abnormalities. The CT findings and the differential diagnosis are discussed.

Soliton at the zero-group-dispersion wavelength of a single-model fiber

It is shown that solitons emerge from initial pulses of arbitrary shape and amplitude whose central frequencies are at the zero-dispersion point. The initial threshold power is substantially reduced from that required for experiments to date. The use of these solitons is thus an attractive alternative to both the linear and the nonlinear communication schemes that have been proposed to date.

Structure of A-DNA in solution

The structure of DNA in aqueous trifluoroethanol solutions containing more than 70% (vol/vol) trifluoroethanol, where it has been proposed to have the A-conformation, has been studied by the technique of electric linear dichroism. The data demonstrate that both linear phi X174 DNA [5386 base pairs (bp) long] and a 172-bp fragment of sea urchin 5S RNA gene are in the double-helical A-form in the alcoholic solution and that two of the important structural parameters, the base tilt and the base-pair translation along the helical axis, are the same as in the A-form structure of crystalline double-helical d(GGTATACC). Despite its molecular length, the limiting reduced dichroism (-1.41) of the phi X174 DNA in low-salt aqueous solution is near the theoretical limit (-1.50) for DNA with base planes perpendicular to the helical axis. Transformation of this DNA and also of the 172-bp fragment to the A-structure in alcohol solutions reduces the experimental value of the dichroism to about -1.04, which agrees almost exactly with the value of -1.03 calculated for the A-form crystal. The base-pair translation along the helical axis was determined from relaxation of the DNA dichroism when the electric field is turned off. The 172-bp fragment is found to have a base-pair translation of only 2.6 A in the A-structure and is thus the same as in A-DNA fibers and in the A-form oligomers crystals. We conclude from the coincidence of the base-pair translation and the apparent values of the base tilt that the A structures are identical or nearly so in the solution and solid states. Comparison of the phi X174 data with data on smaller DNA fragments and with the data on the 172-bp sea urchin gene fragment unambiguously confirms that, in aqueous solution, the experimental reduced electric dichroism of B-DNA is highly dependent on molecular length, while the dichroism of the A-DNA form in alcoholic solutions is independent of molecular length at least in the range from 172 to 5386 bp.

Biosynthetic thiolase from Zoogloea ramigera. II. Inactivation with haloacetyl CoA analogs

The thiolase involved in biosynthesis of poly-beta-hydroxybutyrate in Zoogloea ramigera generates an acetyl-enzyme species during catalysis. Up to 0.86 [14C] acetyl eq/subunit of this homotetrameric enzyme is accumulated by acid precipitation in the presence of [14C]acetyl-CoA. Gel filtration of the same solutions produced only 7% acetyl-enzyme suggesting hydrolytic lability of the acetyl-enzyme during the 10-min isolation at 4 degrees C. In an effort to identify active site residues which may function as basic groups to deprotonate at C-2 of acetyl-CoA to generate the required nucleophilic equivalent in carbon-carbon bond formation, we have prepared and tested haloacetyl-thioesters, oxoesters, and amides in the panthetheine pivalate series (Davis, J. T., Moore, R. N., Imperiali, B., Pratt, A. J., Kobayashi, K., Masamune, S., Sinskey, A. J., and Walsh, C. T. (1987) J. Biol. Chem. 262, 82-89). The [14C]bromoacetyl-oxoester alkylatively inactivates thiolase irreversibly with stoichiometric incorporation of four labels/tetramer. Determination of amino acid composition of the radiolabeled tryptic peptide indicated trapping of Cys-89 (Peoples, O. P., Masamune, S., Walsh, C. T., and Sinskey, A. J. (1987) J. Biol. Chem. 262, 97-102), the same residue modified by iodoacetamide. When the bromoacetyl-thioester was used, inactivation was pH-dependent. The data are consistent with the competition of two processes, acylation, and alkylation. Direct (rather than secondary) alkylation of thiolase by the inactivator accounts for the significant 14C incorporation into thiolase with the thioester labeled with [14C] in the pantetheine pivalate moiety. It appears likely that the haloacetyl analogs described herein should be generally useful for affinity labeling other enzymes using acetyl-CoA as a substrate.

Integrating ancient and modern medicine in Chinese hospitals. The interaction among technology, traditional Chinese medicine, and health care

Modern industrial society and its industrial processes can sometimes discourage the practice of traditional medicine. The existence and use of traditional Chinese medicine for several thousands of years indicates that it has sound elements. As has been true with features of other ancient, highly developed civilizations, the discipline of traditional Chinese medicine offers a valuable resource in the treatment and prevention of disease. Its scientific aspects and valuable experiences must continue to be developed according to Western scientific methodology. China has initiated a program to utilize modern industrialized technology in the integration of the traditional Chinese and modern Western medical systems. The policy and process aimed at integrating traditional Chinese medicine with Western medicine are presented in this paper. These measures have resulted in considerable utilization and development of the traditional Chinese medicine system, and have had a major impact on the development of public health care, as well as medical technology and science. The positive interactions between these fields of study and existing problems are discussed, and some comments on future expectations are presented.

Identification of a new group of Chlamydia psittaci strains called TWAR

A new group of Chlamydia psittaci strains has been identified. They are called TWAR after the laboratory designation of the first two isolates. Twelve strains were isolated from pharyngeal swabs of different persons with acute respiratory disease in Seattle, Wash., during 1983 to 1986. One strain was obtained from the eye of a child during the trachoma vaccine study in Taiwan in 1965. Nine strains were characterized in this study. TWAR organisms formed intracytoplasmic inclusions in HeLa cells which were morphologically typical of C. psittaci and iodine stain negative (contained no glycogen). Immunological analysis with various chlamydia-specific monoclonal antibodies revealed that TWAR strains belong to the genus Chlamydia, are distinct from C. trachomatis, and are serologically unique among C. psittaci. All TWAR strains so far isolated appear identical serologically. TWAR organisms grew poorly in egg and cell cultures and demonstrated low virulence to mice by intracerebral, intranasal, and intravenous inoculation. Available data suggest that the TWAR strain is a primary human pathogen.

Nonlinear pulse propagation in the neighborhood of the zero-dispersion wavelength of monomode optical fibers

Nonlinear pulse propagation is investigated in the neighborhood of the zero-dispersion wavelength in monomode fibers. When the amplitude is sufficiently large to generate breathers (N > 1 solitons), it is found that the pulses break apart if lambda - lambda(0) is sufficiently small, owing to the third-order dispersion. Here lambda(0) denotes the zero-dispersion wavelength. By contrast, the solitary-wave (N = 1) solution appears well behaved for arbitrary lambda - lambda(0). Implications for communication systems and pulse compression are discussed.