Numerical Investigations of Fiber Orientation Models for Injection Molded Long Fiber Composites

Understanding the effect of fiber orientation on mechanical properties is a primary consideration for long fiber-reinforced thermoplastics in automotive applications. In injection-molded parts, the classical Folgar-Tucker model has been used to predict the shell-core structure of short fiber orientation patterns. However, this model results in a thinner core region for long fiber composites. Recently, the RSC (Reduced Strain Closure), ARD (Anisotropic Rotary Diffusion), and iARD-RPR (improved ARD and Retarding Principal Rate) models are potential models developed in relation to suspension rheology. In addition to improving the inaccurate predictions, a so-called inlet condition of fiber orientation set at the gate is examined in the RSC. In this approach, a significant requirement is to numerically investigate the nature of the shell-core structure, while validating a predictive difference between the orientation models via related experimental data. Dramatic changes in the orientation distribution at various filling times and mold temperatures are discussed herein.

Numerical Predictions of Fiber Orientation for Injection Molded Rectangle Plate and Tensile Bar with Experimental Validations

Fiber composites are the pinnacle of lightweight materials in the automotive industry. The orientation of the reinforcing fibers strongly affects the mechanical performance of the finished part. However, fiber orientation prediction with high accuracy is difficult for a complex flow field in practical injection molding. Recently, an objective model, iARD-RPR (Improved Anisotropic Rotary Diffusion and Retarding Principal Rate), has been significant to provide anisotropic distribution of fiber orientation, such as the well-known skin-shell-core structure. Micro-computed tomography (micro-CT) scan is a state-of-the-art technique for measuring a very high 3D resolution of a specimen's fiber orientation data. According to the micro-CT experiments and injection molding simulations with the iARD-RPR computation, we investigate changes in fiber orientation distributions at different concentrations in a rectangle plate, while the alignment of fibers found in weld line is revealed for tensile bar. Comparisons of the fiber orientation predictions with the validated experimental data are also presented herein.

An Integration of Microstructure Predictions and Structural Analysis in Long-Fiber-Reinforced Composite with Experimental Validation

Long fiber-reinforced thermoplastic (LFRT) composites are a very important lightweight material for practical use by the automotive industry because their mechanical performance is superior to that of short fibers. Microstructures of LFRT products, including fiber orientation state and fiber length distribution, strongly affect their mechanical properties and testing. Prior numerical approaches were limited by their inability to analyze many complex flows. Currently, the 3D numerical technology is able to analyze a varying geometry flow. We therefore aim to derive accurate predictions of fiber microstructure in a reliable 3D flow simulation of an injection molded LFRT composite part, with the use of objective fiber orientation and fiber length models. In addition, the microstructure data imported to calculate appropriate mechanical properties effectively improves the prediction accuracy of structural performance for an LFRT part. In such an integrative simulation, the predictive results are compared to related experimental data for the purpose of evaluation.

A tryptophan metabolite, kynurenine, promotes mast cell activation through aryl hydrocarbon receptor

BACKGROUND

Tryptophan metabolites have been suggested to play a role in immune modulation, wherein those have recently been shown to be endogenous ligands of aryl hydrocarbon receptor (AhR; a unique cellular chemical sensor). However, the involvement of tryptophan metabolites and AhR in modulating mast cell function remains to be fully defined. We therefore investigated that the functional impacts of tryptophan metabolites on human and mouse mast cell responses in vitro and their functional importance in vivo.

METHODS

Three tryptophan metabolites, kynurenine (KYN), kynurenic acid (KA) and quinolinic acid (QA), were examined in terms of their effect on IgE-mediated responses in mouse bone marrow-derived mast cells (BMMCs) and in human peripheral blood-derived cultured mast cells (HCMCs) and on in vivo anaphylactic responses. For evaluation of AhR involvement, we examined the responses of mast cells from AhR-null or AhR-wild-type mice with the use of a known AhR antagonist, CH223191.

RESULTS

Kynurenine, but not KA and QA, enhanced IgE-mediated responses, including degranulation, LTC4 release, and IL-13 production in BMMCs through the activation of PLCγ1, Akt, MAPK p38, and the increase of intracellular calcium. KYN also enhanced cutaneous anaphylaxis in vivo. These enhancing effects of KYN were not observed in AhR-deficient BMMCs and could be inhibited by CH223191 in BMMCs. Further, KYN had similar enhancing effects on HCMCs, which were inhibited by CH223191.

CONCLUSION

The AhR-KYN axis is potentially important in modulating mast cell responses and represents an example of AhR's critical involvement in the regulation of allergic responses.

Flow density of a reversible ratchet

By defining "flow density" in a reversible ratchet, a kind of Brownian motor that runs four processes in a two-dimensional parameter space to complete a cycle, we analytically investigate the behavior of the motor's integrated flow in terms of the magnitude and location of the density maximum. It turns out that flow density gives information that can serve as a guide for obtaining the most suitable integrated flow important in the design of reversible ratchets.

Transesophageal echocardiographic monitoring for transcatheter closure of atrial septal defect

BACKGROUND AND PURPOSE

Transcatheter closure of atrial septal defect (ASD) is generally performed under fluoroscopy alone. Recently, we have used transesophageal echocardiography (TEE) monitoring as an aid in performing this procedure. The purpose of this study was to evaluate the efficacy and complications associated with this use of TEE.

METHODS

Transcatheter closure of ASD was accomplished under TEE guidance simultaneously with fluoroscopic imaging in 11 patients aged 3 to 33 years (weight, 15.4-62.9 kg). TEE was successfully performed in all patients after endotracheal general anesthesia. The ASDs were reexamined before catheterization. The appropriate placement of the occluder device was evaluated.

RESULTS

Seven cases were uneventful with successful ASD occluder implantation, but one failed because of a large ASD (24.7 mm). In three cases, transcatheter closure was aborted after TEE examination, one with a large ASD (27.05 mm), one with an ASD that was too small, and one with multiple fenestrated ASDs.

CONCLUSIONS

Routine TEE monitoring for transcatheter closure of ASDs is effective for evaluation of ASD before implantation of an occluder, to ensure the proper seating of the occluder after the defect occlusion is complete.

Comparison of invasive and non-invasive measurement of spontaneous baroreflex during anesthesia

BACKGROUND

Many works have shown that beat-to-beat variations in systolic arterial pressure (SAP) could be used for the assessment of cardiac baroreflex function. The purpose of this study was to evaluate whether Finapres, a non-invasive device to measure systolic arterial pressure, could serve as an acceptable alternative to intra-arterial catheterization for assessing the spontaneous baroreflex during anesthesia.

METHODS

Thirty ASA class I patients scheduled for surgical hepatic and gastric tumor excisions were enrolled in this study. Spontaneous baroreflex sensitivity (SBR) during anesthesia was calculated by sequence analysis of beat-to-beat variations in systolic arterial pressure and R-R intervals. Data obtained from Finapres were compared with those from standard intra-arterial catheterization technique.

RESULTS

SBR values determined by non-invasive and invasive blood pressure measurement technique were precisely correlated (r = 0.96) and the mean difference was about 0.22 ms/mmHg (12.5%). However, the individual data might differ by -0.52 to +0.96 ms/mmHg (-35% to +60%).

CONCLUSIONS

Finapres may trace the changes of SBR during anesthesia and provides similar results as does invasive method but individual variation exists.

Spinal anesthesia in MELAS syndrome: a case with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes

MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) is one of the classic mitochondrial encephalomyopathies with variable clinical presentation and multisystem involvement. Enhanced sensitivity to neuromuscular blockade or anesthetic agents and susceptibility to malignant hyperthermia in these patients have ever been reported, all of which complicate the management of general anesthesia. To avoid these appalling troubles in general anesthesia, we chose spinal anesthesia for a patient with MELAS syndrome receiving appendectomy. The patient obtained adequate anesthesia and good recovery without neurologic sequelae. Although there is little information about the application of regional anesthesia in MELAS patients, we demonstrate that it may be a satisfactory choice. However, it is suggested that regional anesthesia is performed only when neurological abnormalities of spinal cord or peripheral nerves are definitely ruled out.

Phosphorylated tau can promote tubulin assembly

Phosphorylation can affect the function of microtubule-associated protein tau. Here, the human brain tau with 441 amino acids was phosphorylated by cyclic-AMP-dependent protein kinase (PKA) or glycogen synthase kinase-3beta. PKA-phosphorylated tau (2.7 mol phosphates/mol) does not promote tubulin assembly as judged by spectrophotometric and atomic force microscopy measurements, unless trimethylamine N-oxide (TMAO), a natural occurring osmolyte, is included in these assays. TMAO is also found to promote tubulin assembly of glycogen synthase kinase-3beta-phosphorylated tau (1.6 mol phosphates/mol). TMAO does not act by causing a chemical dephosphorylation of phosphorylated tau, but it acts to overcome the functional deficit caused by phosphorylation. PKA-phosphorylated tau binds to tubulin in the presence of TMAO and lowers the critical concentration of tubulin needed for assembly. From these data, we conclude that PKA-phosphorylated tau retains the ability to bind tubulin and promote tubulin assembly. TMAO is required, however, to sensitize the reaction. Possible uses of TMAO in relation to studies of tubulin assembly in vitro, in intact cells, and in relation to Alzheimer's disease are presented in this report.

Hepatobiliary dysfunction as the initial manifestation of disseminated cryptococcosis

A case of hepatobiliary dysfunction as the initial manifestation of disseminated cryptococcosis is described. The patient was admitted with symptoms of hepatitis with cholestatic jaundice. Antibody tests for hepatitis B and C and human immunodeficiency virus were negative. The patient continued to deteriorate clinically. Eventually, the patient succumbed to hepatic failure. Autopsy disclosed systemic cryptococcosis that caused extensive necrosis of the liver. In review of the literature, only nine cases of cryptococcal infection presenting as hepatitis, cholangitis, and cholecystitis as initial manifestation were reported. Four of these patients had been subjected to exploratory laparotomy for clinical suspicion of acute abdomen. One patient developed cirrhosis as a result of cryptococcal hepatitis. Two patients succumbed to hepatic failure. Cryptococcosis is known to occur commonly in immunocompromised patients, yet only two reported cases presenting as hepatitis were associated with immunocompromised status.

Natural methylamine osmolytes, trimethylamine N-oxide and betaine, increase tau-induced polymerization of microtubules

The natural osmolyte trimethylamine N-oxide (TMAO) at 200 mM increases the extent and the rate of formation of polymerized microtubule (MT) complex caused by tau. TMAO at this concentration has no effect on tubulin alone. Urea at 200 mM blocks tubulin assembly caused by tau, but this inhibition can be reversed by an equal amount of TMAO. Besides TMAO, betaine, another natural osmolyte, was found to have the same effects on MT as TMAO. On the contrary, glycerol (a carbohydrate osmolyte) and glycine (an amino acid osmolyte) do not increase tau-induced MT assembly. The mechanism by which TMAO and betaine enhance tau's effectiveness is not known, but physical studies suggest that the secondary structure of tau is not appreciably changed by 200 mM TMAO. This is the first report showing that natural osmolytes, TMAO and betaine, at a near physiological concentration are able to stimulate tau-induced tubulin assembly.

The commissioning of a flexible low-cost multipurpose X-ray beamline at SRRC

A low-cost multipurpose X-ray beamline has been commissioned at the bending magnet B15 of the Synchrotron Radiation Research Center (SRRC). The beamline is constructed in such a way to accommodate the various needs of small research consortia, from universities or research institutes, whose requirements of a beamline facility are quite diverse while under limited funding support. Flexibility is the special feature of this beamline. It is capable of performing quick test measurements without a prolonged reviewing process. Switching between different techniques, such as white-beam irradiation, EXAFS and X-ray scattering, can be achieved within 1 h. Novel experiments, such as energy-dispersive small-angle scattering experiments and energy-dispersive reflectivity measurements, can also be performed.

The endocrine secretion of human insulin and growth hormone by exocrine glands of the gastrointestinal tract

The exocrine pancreas, liver, and submandibular glands of the rat were used to express and secrete two exogenous, human protein hormones (growth hormone and insulin) into blood at physiological concentrations. Transfection, expression, and secretion were achieved by the in vivo retrograde injection of plasmid DNA into the secretory ducts of these glands. Pancreatic acinar cells secreted physiological concentrations of growth hormone into the circulation, and its secretion was enhanced by cholinergic stimulation. A human insulin gene was engineered to allow normal processing of insulin in non-beta cells. With this gene, the secretion of human insulin by the exocrine pancreas normalized elevated blood glucose levels in diabetic rats. These in vivo observations demonstrate the utility of retrograde ductal administration of naked DNA into exocrine organs as a novel method for the regulated systemic delivery of protein-based pharmaceuticals.

Comparison of stored and secreted rat pancreatic digestive enzymes by mass spectrometry: alpha-amylase

As part of a continuing effort to better understand the mechanisms of protein secretion, we compared the mass of pancreatic digestive enzymes, in resting and stimulated states, both in secretion and in the zymogen granule to determine whether their secretion is accompanied by chemical modification. Mass spectra were obtained applying the electrospray method on samples separated by reverse-phase HPLC. We report here our results for alpha-amylase (1,4-alpha-D-glucan glucanohydrolase EC 3.2.1.1). The data illustrate structural differences between states and compartments for this enzyme. Multiple isozymes were identified from the mass spectra, varying roughly from 52 to 60 kDa. On the basis of mass comparisons, not all of the products seen in the zymogen granule were found in secretion, nor were all secreted isoforms in the granule. Stimulation of protein secretion with a cholinergic agonist, led to time-dependent changes in the number and masses of isoforms in secretion, leaving only one of five resolvable forms in the granule. Only one form, 55.5 kDa, was found in all samples, granule and secretion. In addition to these differences, microheterogeneities of 400 Da or less were observed. The data suggest the differential or non-parallel release of different amylase forms and their chemical modification during the secretion process. As such, release appears to involve a third, intermediate compartment, between zymogen granule to ductal space, such as the cytoplasm, in which chemical modification takes place.

Characterization of the manganese-resistant mutants derived from Vibrio parahaemolyticus

The virulence and some related factors of Vibrio parahaemolyticus are regulated by the level of iron. In this study, five Mn-resistant mutants were selected after N-methyl-N'-nitrosoguanidine treatment and two transfers in medium containing high levels of manganese chloride. Production of siderophores and the 77-kDa iron-regulated outer-membrane protein and the bacterial growth in these Mn-resistants were deregulated, as compared with the wild-type strain. In addition, the regulation of these phenomena was partially or completely restored by the introduction of Escherichia coli fur gene. Also, the total cellular protein profiles of the wild-type and mutants showed that production of some proteins were positively or negatively regulated by iron, and expression of some of these proteins remained unaffected in these mutants. These results suggested the presence of a complicated iron regulation system, similar to the Fur system of E. coli, in this pathogen.

Selective determination of adenine-containing compounds by capillary electrophoresis with laser-induced fluorescence detection

Capillary electrophoresis coupled with laser-induced fluorescence detection provides a selective analysis of mixtures of adenine-containing compounds (adenine, adenosine, cAMP, AMP, ADP, and ATP) that are derivatized using chloroacetaldehyde as a fluorogenic reagent. The components can be detected with linear response over the concentration range of 10(-4) to 10(-9) M, and the detection limit corresponds to 5 to 10 x 10(-19) mol for each nucleotide. Analysis is achieved in less than 10 min with high separation efficiencies (up to 400,000 theoretical plates) and shows good reproducibility for migration times (0.5 to 1.0%) and peak heights (2.8 to 7.7%). To demonstrate the rapid analysis of small-volume samples, the adenine-containing compounds present in an oocyte from Xenopus laevis are determined.

Urinary N-acetyl-glucosaminidase excretion and environmental lead exposure. Green Cross Health Service Association Study Group

To understand the relationship between chronic low-level lead exposure and renal function, residents living nearby a lead battery factory for more than 10 years were selected and entered in this cross-section study. The residents living in the 1st village, within 500 m from the factory, were grouped in group 1; those in the 2nd village, within 1,000-1,500 m, in group 2, and those in the 3rd village, far from any lead-contaminated sources, in group 3. Twenty-four-hour urinary N-acetyl-glucosaminidase (NAG) was detected as early indicator of renal damage, and an ethylenediamine-tetraacetic acid mobilization test was performed to estimate total body lead burden of lead-exposed persons. Blood lead level (BLL) showed a significant difference among the three study groups. The further the distance between the group and the factory, the higher BLL. The results showed a significant high prevalence of abnormal urine NAG excretion in the chronic lead-exposed group, although BLL and body lead burden of these persons were within the 'normal' range. A significant correlation between body lead burden less than 200 micrograms and 24-hour urine NAG excretion and a dose-response relationship between them were found. These observations suggested that lead was the possible cause of abnormal renal tubular function in persons with chronic low-level lead exposure, but this effect became blunt when body lead burden was more than 200 micrograms. The possible explanation may be that high body lead burden from long-term exposure will deplete the kidney of NAG or render it insensitive to the effects of lead exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Neural regulation of lysozyme secretion from tracheal submucosal glands of ferrets in vivo

To investigate how central and peripheral nerves affect lysozyme secretion from tracheal submucosal glands in ferrets we injected substance P (20 nmol/kg in 200 microliters) intracisternally or intravenously into anesthetized artificially ventilated ferrets. We collected 3-ml samples from a perfused (3 ml/5 min) segment of trachea in situ during 15 min before and 45 min after injection of substance P. Content of lysozyme, a specific marker of tracheal submucosal gland serous cell secretion in ferrets, was measured spectrophotometrically in each sample. Intracisternal substance P increased peak lysozyme output threefold compared with baseline. This increase was abolished completely by cutting both superior laryngeal nerves (SLN) and was partially inhibited by atropine, phentolamine, or propranolol. Intravenous substance P increased peak lysozyme output 10-fold compared with baseline. This increase was partly abolished by cutting both SLN. We concluded that intracisternal substance P stimulated the central nervous system (CNS) and activated cholinergic, adrenergic, and nonadrenergic noncholinergic secretomotor nerves to tracheal glands and that intravenous substance P increased lysozyme secretion both by acting directly on tracheal glands and indirectly on the CNS to activate secretomotor nerves.

A cloned ompR-like gene of Streptomyces lividans 66 suppresses defective melC1, a putative copper-transfer gene

Expression of tyrosinase in Streptomyces requires functional MelC1 protein, which is postulated to transfer copper to apotyrosinase. We have previously isolated a mutant of Streptomyces lividans, HT32, that phenotypically suppressed mutations in cloned melC1 (H.-C. Tseng and C. W. Chen, in preparation). Plasmid pLUS132, containing an ATG to ATA transition at the initiation codon of melC1, was used for cloning the suppressor gene from HT32. A 1687 bp suppressor DNA was isolated that contained two characteristic Streptomyces coding sequences: a 217-amino-acid open reading frame (cutR) and a truncated open reading frame (cutS) downstream. Subcloning analysis attributed the phenotypic suppression activity to the putative cutR gene from HT32. The putative CutR exhibited similarity to the response regulator OmpR of the osmoregulatory signal-transduction system in Escherichia coli. The truncated CutS resembled, to a lesser degree, the N-terminus of EnvZ, the histidine protein kinase counterpart of OmpR. DNA hybridizing to the cloned cutR-cutS sequence was detected in 16 other Streptomyces species. We postulate that the putative cutR-cutS operon regulates copper metabolism in Streptomyces.

The melanin operon of Streptomyces antibioticus: expression and use as a marker in gram-negative bacteria

The melC operon of Streptomyces antibioticus contains two genes, melC1 and melC2, necessary for the production of melanin pigment. We transferred the coding sequence of melC1 and melC2 to Escherichia coli plasmid pMTL23 such that its transcription was under the control of the lac promoter and melC1 was translationally fused to the lacZ alpha fragment. E. coli cultures containing this plasmid, pIF413, produced melanin after overnight incubation on 2YT agar supplemented with 0.1 mM CuCl2, 0.36 mM IPTG (or 0.2% lactose), and 2 mM tyrosine. Erwina carotovora could also be transformed by pIF413 to produce melanin. Two shuttle vectors were constructed: pLUS415 for E. coli and Streptomyces, and pLAF413 for E. coli and Xanthomonas campestris. These vectors confer melanin pigmentation in all the hosts that harbor them. The melC sequence provides the vectors with a convenient cloning marker for insertional or replacement inactivation.

Structure-activity relationships of chloride-sensitive fluorescent indicators for biological application

The application of the quinoline derivative 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ) to the measurement of membrane transport of chloride in biological systems was reported recently (N.P. Illsley and A.S. Verkman (1987) Biochemistry 26, 1215-1219). To understand the structure-activity relationships of compounds with chloride-sensitive fluorescence properties, 19 structural analogs of SPQ having a single quaternized nitrogen heteroatom were synthesized and characterized. The effect of variations in ring structure, length of sulfoalkyl chain, position of ring substituent, and nature of ring substituent were examined. For each compound, the water solubility, octanol:water partition coefficient, absorbance and fluorescence spectra, fluorescence lifetime, and Stern-Volmer constants (Kq) for quenching by a series of anions were measured. All compounds were quenched by chloride, bromide, iodide, and thiocyanate, but not by cations, sulfate, phosphate, nitrate, or by pH (5-8); several compounds were quenched slightly by bicarbonate (Kq = 8-12 M-1). High chloride sensitivity (Kq greater than 50 M-1) required the presence of a quinoline backbone substituted with electron-donating groups such as methyl and methoxy, but did not depend on length of the sulfoalkyl chain or on the position of ring substituents (positions 2-7). All compounds with high chloride sensitivity had fluorescence excitation spectra in the ultraviolet (excitation maximum less than 350 nm) and fluorescence lifetimes greater than 15 ns. These results establish a set of guidelines for synthesis of chloride-sensitive fluorescent indicators tailored for specific biological applications.

Insulinoma. An immunocytochemical and morphologic analysis of 95 cases

One hundred twenty-seven insulinomas from 95 cases (1 malignant and 94 benign) were studied pathologically. Thirty-six tumors (35 cases) were examined by electron microscopy. Typical beta-cell secretory granules of crystalloid-form cores and/or atypical secretory granules were discerned in all tumors examined. A new type of secretory granule, with high electron-dense crystalloid-form cores and moderate electron-dense granular substance filling the space between the core and the limiting membrane, were observed in two cases. Among 68 insulinomas (67 cases) subjected to immunocytochemical investigations with ten peptide hormones (insulin, glucagon, somatostatin, pancreatic polypeptide (PP), gastrin, motilin, secretin, vasoactive intestinal polypeptide (VIP), gastric inhibitory polypeptide (GIP), and neurotensin), 42 were found to be multihormonal, varying from two to four peptides secreted. The hormones contained were insulin, glucagon, PP, somatostatin, and gastrin in different combinations. One patient had hyperinsulinemia and hypergastrinemia concurrently, and two islet tumors were excised at an interval of 10 months. Both electron microscopy and immunocytochemistry confirmed the presence of beta- and alpha-cells in the first tumor, whereas the second tumor revealed only G-cells by electron microscopy, and G- and beta-cells on immunocytochemical staining. The morphologic and immunocytochemical characteristics of the insulinomas in this series are discussed.

Regulation of digestion. I. Effects of glucose and lysine on pancreatic secretion

Previous cell-free studies have shown that glucose selectively elicits the release of amylase from pancreatic zymogen granules, whereas lysine promotes the selective release of trypsinogen. To investigate the expression of these effects in situ, glucose or lysine was injected into the celiac artery of anesthetized rats, either alone or together with the pancreatic secretagogue cholecystokinin, to evaluate their effects on the secretion of amylase and trypsinogen by the pancreas. When given alone neither substance significantly changed the output of either enzyme. However, when given with cholecystokinin, each altered the effect observed with injection of cholecystokinin alone. The injection of glucose resulted in a twofold increase in both peak and total amylase output without significantly increasing trypsinogen secretion, whereas lysine increased both peak and total trypsinogen output by about 50%, leaving amylase output unchanged. These findings provide in situ confirmation for the selective enzyme release produced by glucose and lysine in cell-free studies and suggest that such end products of digestion can regulate the digestive process by modifying the secretory response of the pancreas to cholecystokinin.

Regulation of digestion. II. Effects of insulin and glucagon on pancreatic secretion

The endocrine islet-cell hormones insulin and glucagon are secreted at high concentrations into an intrapancreatic portal circulation and have been reported to affect the secretion of digestive enzyme by the exocrine pancreas. In the present experiments, insulin and glucagon were injected into the celiac artery of anesthetized rats to evaluate their effects on the secretion of amylase and trypsinogen by the pancreas. Neither hormone when given alone significantly changed the output of either enzyme. However, when given with the pancreatic secretagogue cholecystokinin, each altered the effect of injection of cholecystokinin. In a dose-dependent fashion insulin increased trypsinogen output without affecting amylase output, whereas glucagon inhibited amylase output and left trypsinogen output unchanged. Thus, both hormones produced a more trypsinogen-dominant pancreatic juice than that observed with cholecystokinin alone, although in different ways. These findings suggest that the endocrine hormones insulin and glucagon may regulate secretion of digestive enzymes by the pancreas by modulating the response to stimuli of overall protein secretion such as cholecystokinin.

Current surgical interests in China

Until recently, China had been isolated from Western countries for almost 30 years. Surgeons of Western countries, perhaps, are interested to know what is happening in surgery in China. This communication reviews the current interests in Chinese surgery. It is by no means complete, nor is that the intention. The intention is to introduce to our foreign colleagues a general overview of some highlights in Chinese surgery.

Food, duodenal extracts, and enzyme secretion by the pancreas

Previous studies have reported that injection of duodenal extracts from rats fed different meals into the celiac artery of recipient rats elicited the secretion of related pancreatic enzymes. We have been unable to reproduce the enzyme-specific increases in the average output of particular enzymes that were observed but did find changes similar in direction, although not magnitude, to those reported previously. The outputs of amylase and trypsinogen were compared by plotting individual data points and performing a regression analysis on them. The injection of duodenal extracts from lactalbumin hydrolysate-fed rats led to trypsinogen secretion being favored over that of amylase and vice versa for extracts from rats fed a glucose meal. In addition, it was found that cholecystokinin-pancreozymin produced a dramatic nonparallel transport of these two enzymes with amylase secretion being augmented to a greater degree than trypsinogen secretion. The relation between their outputs was curvilinear, i.e., the amylase dominance of secretion became more pronounced as overall enzyme output (not dose of hormone) increased. Thus, this nonparallel secretion does not seem to be the results of a discontinuous switch in the character of enzyme secretion produced by the hormone but a graded effect reflecting the magnitude of the response.

Salmonellae in Tan-Shui River (author's transl)

A total of 61 water samples collected from 10 stations along the Chilung River, Hsintien Chi, Ta-han River were examined for salmonellae from Sep. 1978 to July 1979. There were 227 Salmonella strains isolated. After biochemical test and serological identification, 31 serotypes were verified. They were classified into 12 groups: B, C1, C2, C3, D1, E1, E2, E4, F, G2, H and R. S. derby was isolated in the highest rate (27.75%) and was followed by S. kuru (11.89%), S. worthington (7.93%), S. cambridge (5.73%), S. panama (4.41%). Twenty-three serotypes were firstly recovered from Taiwan area.

Insulinoma. Experience in surgical treatment

Sixty cases of insulinoma were treated surgically. The possible causes for failure to find the tumor during exploratory surgery are discussed. Simple enucleation is preferred in most cases of single or a few insulinomas. A technique of enucleation with minimal chance of injury to adjacent pancreatic ducts and larger blood vessels can be used. When no tumor is found after thorough exploratory procedures, controlled staged resection of the pancreas under blood glucose monitoring is the procedure of choice. Postoperative complications are common but the late results are gratifying provided the operation is carried out early in the course of the disease.