The synthesis of the aortic valve closure sound of the dog by the mean filter of forward and backward predictor

The application of a new algorithm, the mean filter of forward and backward predictor, to synthesize the aortic component of the second heart sound (A2), according to an exponentially damped sinusoid model, is described. The resulting estimates of four modeling parameters composing each sinusoid of A2 (amplitude, damping factor, frequency, and phase) were used to synthesize the original aortic sounds. The synthesized sounds were then compared to the original sounds recorded on the thorax of six dogs and an error index was computed. The results show that the method is more precise than the forward predictor filter, the backward predictor filter, and the improved KT algorithm. The new algorithm is also highly stable and the error index between the original A2 and the synthesized waveforms is always less than 1%.

The identification of female sandflies of the subgenus Larroussius by the morphology of the spermathecal ducts

The complete spermathecae of 13 species of Larroussius were dissected and examined. The base of the duct of 4 species (aculeatus, guggisbergi, tobbi, wui) is bell-shaped: they are easily distinguished by differences in shape. Five other species (perniciosus, pedifer, longicuspis, perfiliewi, galilaeus) have lateral structures at the base of the duct: slight differences between perniciosus, pedifer and longicuspis distinguish these species: the structures of perfiliewi and galilaeus are the same. Species of a third group (neglectus, syriacus) have a common duct with no lateral structures: they are distinguishable by minor differences. Two species (ariasi, orientalis) from a fourth group with expanded distal parts of the duct; the size and shape of the expanded parts easily separates the species. The study shows a great variation in the morphology of the base of the spermathecal ducts of Larroussius and confirms the value of this feature in identifying otherwise indistinguishable females of the subgenus.

In vivo catalysis of a metabolically essential reaction by an antibody

We have established a growth selection requirement for a catalytic antibody with modest chorismate mutase activity. Conversion of (-)-chorismate into prephenate is the key step in the biosynthesis of the aromatic amino acids tyrosine and phenylalanine. Strains of the yeast Saccharomyces cerevisiae containing an insertion mutation in the structural gene for the enzyme chorismate mutase (EC 5.4.99.5) require exogenous supplements of these two amino acids for efficient growth. Intracellular expression of the heterologous antibody catalyst in one such strain, identified by random mutagenesis and genetic selection, provides a substantial growth advantage under auxotrophic conditions; complementation was not observed with an unrelated esterolytic antibody. In addition to demonstrating that tailored immunoglobulin catalysts can carry out vital biochemical reactions in vivo, these experiments provide a powerful selection assay for identifying genetic changes within the antibody molecule itself that augment chemical efficiency.

Evaluation of immunoglobulins from plant cells

Expression of cDNA constructs encoding full-length mouse immunoglobulin chains with their native leader sequences or fusion constructs substituting the native leader with a pre-pro sequence derived from Saccharomyces cerevisiae yielded blocked N-termini on the gamma chain or the correct amino terminal sequence on the mature kappa chain. Lectin binding assays revealed that assembled immunoglobulin complexes contained a glycosylated heavy chain. The attached glycan was resistant to digestion by endoglycosidase H and its lectin binding pattern was distinguishable from that of the mammalian glycan. The results indicated processing of the immunoglobulin carbohydrate in the tobacco Golgi to yield a complex oligosaccharide. Secretion of antibody by protoplasts isolated from regenerated transgenic plants or from suspension callus cells was demonstrated by pulse-chase labeling experiments. When purified, the tobacco-produced antibody was found to possess the antigen binding and catalytic properties of the murine monoclonal antibody. Kinetic parameters (Km, Ki, Vmax, and kcat) of the tobacco-derived antibody were comparable to those of the mouse-derived antibody. The results in general show that the endomembrane system of tobacco cells possesses cognate mechanisms for the recognition of diverse leader sequences. These signals can be used to initiate the assembly, processing, and secretion by plant cells of complex foreign proteins.

[Cyclic endometrial changes, ovulation and serum estradiol and progesterone levels in female sterility]

Serial endometrial biopsies and determinations of serum E2 and P levels by radio-immunoassay were performed in 11 women with idiopathic sterility. B ultrasound was employed to monitor the development of follicles and the exact ovulation day. In 9 cases ovulation was observed and normal endometrial changes according to Noyes' criteria with normal cyclic changes of E2 and P levels were present in only 4 cases. 5 ovulated from follicles of smaller size and the secretory phase of the endometrium was delayed. The asynchronous development of endometrium associated with lowered E2 in the follicular phase was deemed to interfere with implantation even in the presence of normal fertilization. Two patients failed to ovulate on account of atretic follicle in one and LUFS in the other. The authors suggest that in idiopathic sterility, especially in the presence of atypical endometrium on the first day of menstruation the E2 levels in the follicular phase and endometrial status on the 3rd-4th day after ovulation should be given due attention.

Yeast expression of a catalytic antibody with chorismate mutase activity

The catalytic antibody 1F7 promotes the rearrangement of chorismate into prephenate. We cloned and sequenced the genes encoding this catalyst to determine the origin of the observed rates and specificity. The antibody cDNAs were modified and inserted into inducible expression vectors. Simultaneous intracellular expression of the light and truncated heavy chains in strains of the yeast Saccharomyces cerevisiae lacking natural chorismate mutase resulted in the production of properly folded and assembled Fab antibody. Assembly of the light and heavy immunoglobulin chains is roughly 60-70% efficient in our in vivo system, lagging behind light chain synthesis throughout log and stationary phase. Nevertheless, high intracellular levels of functional Fab antibody (0.1% of total cellular protein) were obtained with an ultra-high copy number plasmid. As yeast-derived 1F7(Fab) catalyzes the chorismate mutase reaction with the same specific activity as antibody isolated from the hybridoma, our expression system now makes possible the application of classical and "reverse" genetics to the study and improvement of this first-generation abzyme.

Purification and characterisation of the TnsB protein of Tn7: a transposition protein that binds to the ends of Tn7

Tn7, a large bacterial transposon encodes 5 proteins required for its transposition. We report a rapid and easy purification of one of these proteins, TnsB, from an overexpression strain. This protein was shown to bind to the ends of Tn7, in a bandshift assay, in two distinct stages as a function of protein concentration. DNasel footprinting at each end of Tn7 showed that the TnsB recognition sequence, a set of 22 bp repeats, plus Tn7 termini are protected. Binding of TnsB appeared cooperative but was only observed above a threshold concentration of protein. ATP and Mg2+ had no effect on the pattern of protection, nor did addition of other Tn7-encoded proteins. Hydroxyl radical footprinting, performed at the right end, showed that TnsB binds preferentially to one side of the DNA helix.

[Observation of enzyme histochemistry and ultrastructure of brain in kindling rats with epilepsy induced by intraperitoneal injection of coriaria lactone]

Kindling model of epilepsy induced by intraperitoneal injection of Coriaria lactone (CL) was used in the experiment. The dose of CL was 1.25 mg/kg. Thirty rats in various periods of kindling were killed and the materials of cerebral cortex, hippocampus and cerebellum were drawn. The enzyme activities of AchE, NADHD, CCO, LDH, SDH, AcP, ANAE and AkP of these areas were observed with enzyme histochemical techniques. In another three kindled rats, two blank control rats and two NS control rats, the ultrastructure of neurons in hippocampus were observed. The results of experiments showed an increased activity of enzymes related to saccharometabolism and energy metabolism, indicating that the metabolism of brain in rats was increased by repeated kindling seizures. The mechanism of kindling seizure induced by CL may be related to inhibitory effect of CL on AchE activity of brain. The degeneration damage of brain neurons in kindled rats may result from using CL for a long time.

[Proliferation of Reed-Sternberg cells in 5 Hodgkin's cell lines]

Using the monoclonal antibody Ki-67 that detects a cell proliferation-associated human nuclear antigen, incorporations of bromodeoxyuridine (Brud) and 3H-Thymidine, we studied the proliferative capacity of Reed-Sternberg (RS) cells in Hodgkin's cell lines L428, KM-H2, Holden, L540 and L591. The results revealed that in all cell lines, except L591, more than 55% of RS cells were found positive for Ki-67, and over 50% of them had Brud incorporation 5 days after cultivation. The positive score for 3H-Thymidine incorporation was low, and it is assumed that the time taken for 3H-Thymidine in cultivation was short. It shows that at least half of RS cells in these cell lines have proliferation-associated nuclear antigen or can synthesize DNA, and so they are proliferative.

Determination of the enantiomeric purity of scopolamine isolated from plant extract using achiral/chiral coupled column chromatography

The optical purity of scopolamine derived from Datura sanguinea was determined using coupled column chromatography. A C18 column was used to separate scopolamine from the additional alkaloids and other biological material present in the vegetal extract. The C18 column was coupled through a six-port switching valve to two beta-cyclodextrin columns in series which were used to resolve the scopolamine enantiomers. A single acetylated beta-cyclodextrin column gives equivalent results to the native cyclodextrin columns because of slightly higher enantioselectivity for scopolamine. A multistep extraction procedure is used to isolate scopolamine from the vegetal material. 4-6% of the scopolamine in the final extract was found to be the d enantiomer. Sample extracts as well as commercial scopolamine hydrobromide were treated under various conditions commonly encountered during typical commercial extraction procedures and analyzed in order to determine if the d enantiomer was present in the original material or if it was produced during the extraction process and, if so, determine which step and conditions contribute to racemization. Both the salt and the extract were found to be susceptible to racemization under basic conditions (greater than or equal to pH 9) although the extract appeared to be more susceptible than the salt. Tropic acid formed from the hydrolysis of scopolamine seemed to be completely racemized even though the remaining scopolamine was only partially racemized. Within experimental error, no d enantiomer was found in the original fresh plant material.

[A kindling model of epilepsy induced by intraperitoneal injection of coriaria lactone in rats]

Fifty adult male Sprague-Dawley rats were divided into five groups. Intraperitoneal injections of various doses of coriaria lactone (CL, 0.75, 1.25, 1.75, and 2.0 mg/kg) and normal saline were given respectively per 2 days. The behavior of the rats was observed and the ECoG was recorded by telemetric method. The results of experiments show that a kindling model of epilepsy can be established by intraperitoneal injection of CL in rats. This chronic experimental model is of value for application because it is easily established and the rate of being kindled is relatively high, but the mortality is low, and the kindling effect can last well. The model can avert the pathological change caused by artificial injury to brain, so it is advantageous to the research on neurochemistry and ultrastructure. In our experimental condition, it is optimal to select 1.25 mg/kg or 1.75 mg/kg as the dosage of CL for establishing kindling model.

Determination of intracellular pH and PCO2 after metabolic inhibition by fluoride and nitrilotriacetic acid

Mean intracellular pH (pHi) and PCO2 (PiCO2) have been analysed based on pH and total CO2 measurements in tissue homogenates. Tissues were sampled from undisturbed worms (Sipunculus nudus), squid (Illex illecebrosus), trout (Salmo gairdneri), toads (Bufo marinus), and rats. Homogenate metabolism was inhibited by the addition of potassium fluoride and nitrilotriacetic acid (NTA). Model calculations revealed that the influence of dilution, medium buffers, and contamination by extracellular fluids was negligible. In white muscle tissue the resulting pHi values were virtually the same as found in studies using DMO (dimethyloxazolidinedione). If large fractions of mitochondria were present (e.g. in heart muscle), DMO derived pHi values were considerably higher, probably representing overestimates. Homogenate derived pHi values are concluded to represent the effective mean pHi by taking into account pH gradients, and the volumes and buffering of cellular compartments. High time resolution and small variability make this method especially useful to assess rapid changes in pHi, e.g. in exercising animals.

Acid and ion transfer across the gills of fish: mechanisms and regulation

This review examines the mechanisms and regulation of ion and acid transfers across the gills, focussing on freshwater fish. Apical ion-exchange mechanisms (i.e., [Formula: see text] and [Formula: see text] exchange) are shown to play an important though not exclusive role in acid–base transfers. Under some circumstances, for example when either [Formula: see text] or [Formula: see text] but not H+ levels in plasma are elevated, a second mechanism of acid–base transfer then becomes apparent. This mechanism is thought to involve diffusion of acid–base relevant and "strong" ions through paracellular channels. Factors that affect acid–base transfers across the gills include the external [NaCl] and the nature of the acid–base disturbance, the latter being at least as important as the magnitude of the disturbance. Catecholamines are shown to play an important role in the regulation of acid–base transfers across the gills, acting largely through activation of β-adrenergic receptors. Current evidence, nonetheless, suggests that other elements (e.g., α-receptors, adrenergic and cholinergic neurons) may also be involved.

Localization of calcitonin gene-related peptide in the small intestine of various vertebrate species

Calcitonin gene-related peptide (CGRP) was found extensively in the small intestine of both non-mammalian and mammalian vertebrates using radioimmunoassay and immunocytochemistry. By radioimmunoassay, the levels of CGRP in rats, mice, chickens, bullfrogs and rainbow trout were found to range from 91.5 to 419.1 ng/g tissue. To localize CGRP in the small intestine, we used three different tissue preparations for immunocytochemistry: whole-mount preparations, and frozen and Paraplast sections. The combination of three tissue preparations made it easier to visualize the three-dimensional structure and reduced the possibility of missing the immunoreaction. Immunoreactive cell bodies were found in the plexi in the mammalian species. Dense and regular networks of CGRP fibers were observed in the smooth muscle layers, when examined in whole-mount preparations. In non-mammalian species, however, immunoreactive cell bodies could not be detected, although immunoreactive fibers were present, forming less dense and regular networks. Our results indicate that CGRP-immunoreactive fibers are present in the smooth muscle layers of the intestine from fish to mammals, suggesting that CGRP may be involved in regulating gastrointestinal smooth muscles in vertebrates.

[Studies on the mutagenicity of amrinone and milrinone]

The mutagenicity of domestic new drugs amrinone and milrinone were studied by Ames test, micronucleus test of mouse bone marrow and chromosome aberration assay in CHO cells. The results were as follows: neither amrinone nor milrinone was mutagenic in the Ames test; in chromosome aberration assay, both gave positive results; in mouse micronucleus test, amrinone gave a positive result when mice were exposed to 0.8 LD50 dose, but milrinone gave a negative result. These results suggested that amrinone and milrinone did not induce gene mutation, but amrinone induced chromosome damage both in vitro and in vivo, while the chromosome-damaging activity of milrinone in vitro may be minimized by biodetoxication in vivo.

[Studies on the relation of alkaloids in semen Strychni and its processing]

This paper reports the determination of strychnine and brucine in different parts of Semen Strychni (the seeds of Strychnos nux-vomica and S. pierriana), and makes a comparison of the contents between the crude forms and processed products of the two seeds. Based on the results, the authors have made some discussion about the relationship between the alkaloid distribution in Semen Strychni and its processing.