Atheromatous embolism: varied clinical presentation and prognosis

Microemboli composed of atheromatous debris can produce sudden failure of one or many organ systems. The soft tissues of the lower extremity are almost always involved, and may sustain the only significant injury. Atheromatous embolization occurs more commonly than is recognized, and its incidence may be increasing. We report ten cases that demonstrate the variability in presentation and prognosis. These data and a review of the existing literature suggest an extremely grave prognosis in patients with generalized organ system involvement, as opposed to those patients with involvement of the lower extremity only. Treatment consists of general supportive care. Anticoagulation or lytic therapy appears to be of no benefit, and may actually contribute to embolization. We discuss new pharmacologic agents as possible treatment for the intense local ischemia, and recommend selective use of lumbar sympathectomy in cases of impending loss of lower extremity tissue.

The parascapular flap for treatment of lower extremity disorders

The parascapular flap was used as a free microvascular transfer for soft-tissue resurfacing of 11 lower extremities. The diagnoses included four cases of osteomyelitis, three cases of vascular ulceration, one case of combined osteomyelitis and vascular ulceration, two cases of posttraumatic heel defects, and one case of extensive soft-tissue contracture overlying a posttraumatic defect of the femur. All cases were successful clinically. Anatomically, the parascapular flap is supplied by the cutaneous parascapular artery, a branch of the circumflex scapular artery, which itself derives from the subscapular artery. Flap territory may reach 15 x 30 cm, and the vascular pedicle can extend 14 cm if the subscapular artery is taken. Advantages of this flap include the constancy, length, and caliber of the vascular pedicle; the length and width attributes, which allow both coverage of large wounds and primary closure of the donor defect; and an absence of disruption of musculoskeletal function.

Phenotypes of rotavirus reassortants depend upon the recipient genetic background

We have previously characterized the biological and immunological properties of a simian rotavirus SA11 variant (4F) with an altered genome segment 4. The SA11-4F variant formed large plaques in the presence of protease, formed small clear plaques in the absence of protease, and grew to high titer in the presence of protease when compared to our standard wild type (SA11 clone 3). To determine the genome segment of the rotavirus SA11 variant 4F that encoded the unique protease-associated phenotypes of the variant, reassortants were generated that segregated the outer capsid genes of 4F onto a genetic background derived from either the bovine rotavirus B223 or our standard SA11 wild type (clone 3), both of which have contrasting protease-associated phenotypes. The parental and reassortant viruses were examined to determine which genes from the 4F variant encoded the ability (i) to form large plaques in the presence of protease, (ii) to form small clear plaques in the absence of exogenous protease, and (iii) to grow to significantly higher titer in the presence of protease. These phenotypes could be transferred to a clone 3 genetic background by a single genome segment from the 4F variant segment 4. However, in the 4F/B223 reassortants a different and unexpected situation was found. On a B223 genetic background the same phenotypes segregated with a combination of a minimum of two 4F genome segments, segments 4 and 9. These results indicate that the recipient genetic background onto which the genes of a donor rotavirus are reassorted can affect the phenotypes conferred by the presence of the donor segments. Thus, the results of segregation mapping experiments using reassortant viruses should be interpreted with caution.

Biological and immunological characterization of a simian rotavirus SA11 variant with an altered genome segment 4

We have studied a variant virus isolated from a stock of SA11 virus (H. G. Pereira, R. S. Azeredo, A. M. Fialho, and M. N. P. Vidal, 1984, J. Gen. Virol. 65, 815-818). This virus, designated 4F, was initially identified by its faster electrophoretic mobility for genome segment 4. The variant was analyzed to determine if the altered electrophoretic mobility of genome segment 4 could be correlated with phenotypic changes. Comparison of our standard laboratory SA11 virus (clone 3) with the 4F variant showed the following: (i) The 4F variant possesses a viral hemagglutinin (VP4) with a higher apparent molecular weight than clone 3. (ii) The 4F variant produces large plaques when assayed in vitro, as compared to clone 3. (iii) The 4F variant produces plaques in the absence of proteolytic enzymes, whereas clone 3 does not. (iv) The 4F variant reacts with serotype-specific neutralizing monoclonal antibodies to VP7, but fails to react with several neutralizing anti-VP4 monoclonal antibodies generated to SA11 clone 3. (v) The 4F variant grows to a higher titer and is more stable than clone 3. (vi) The 4F variant produces a VP4 that appears to be more susceptible to cleavage by trypsin than is the VP4 of clone 3. Further analyses with the 4F variant may lead to an understanding of the molecular basis for these altered phenotypes that appear to be related, at least in part, to the product of genome segment 4.

A phase 1a clinical trial of LYM-1 monoclonal antibody serotherapy in patients with refractory B cell malignancies

Ten patients with refractory B cell lymphomas were treated with weekly intravenous infusions of escalating doses of murine monoclonal antibody (MoAb) LYM-1 over four weeks. LYM-1 is a recently developed IgG2a murine MoAb that recognizes a polymorphic HLA-Dr antigen on surfaces of normal and malignant B cells but does not bind to any other normal tissues. MoAb LYM-1 has several advantages for serotherapy, since the antigen it recognizes is not shed from the cell surface and does not modulate in response to MoAb therapy. Furthermore, in vitro studies have indicated significant anti-tumour activity against lymphoma cell lines. In the current trial, dose-dependent levels of free LYM-1 were detected in the serum of all patients, but penetration of extravascular tumour tissues was poor. No significant toxicity or human anti-mouse antibody responses were observed in any patient. Clinical responses were minor and appeared to correlate with the number of infiltrating T cells seen in the initial lymphoma specimens. LYM-1 appears to be well-tolerated and has demonstrated several potential advantages as a therapeutic agent in patients with lymphoma. The mechanism of anti-tumour effect and plans for further clinical studies are discussed.

Respiratory criteria of fitness for surgery and anaesthesia

A retrospective analysis has been undertaken of 53 operations in 42 patients with severe chronic obstructive airway disease. All patients had a forced expiratory volume in 1 second between 0.3 and 1 litre, but the outcome of surgery was successful after their first operations, all of which were elective; 38 of the 42 had uneventful anaesthesia and surgery together with a normal postoperative period, while four had artificial ventilation of the lungs. The best predictors of the use of postoperative ventilation were the arterial PO2 and whether the patient was dyspnoeic at rest.

Molecular properties of p-(dimethylamino)benzaldehyde bound to liver alcohol dehydrogenase: a Raman spectroscopic study

We have studied the binding nature of an aromatic aldehyde to the catalytic site of liver alcohol dehydrogenase from horse (LADH) using preresonance Raman spectroscopy. The compound p-(dimethylamino)benzaldehyde (DABA) is converted to the corresponding alcohol in the presence of nicotinamide adenine dinucleotide (NADH) and a catalytic amount of enzyme at neutral pH. A stable ternary complex of LADH/NADH/DABA can be formed if enzyme and coenzyme are in excess at high pH [Jagodzinski, P. W., Funk, G. F., & Peticolas, W. L. (1982) Biochemistry 21, 2193-2202]. We have obtained the preresonance Raman spectrum of bound DABA by subtracting the contribution of the binary complex of LADH/NADH from the spectrum of this stable ternary complex. In order to understand the normal mode patterns of DABA, four isotopically labeled DABA derivatives were synthesized and their Raman spectra, in solution and in the ternary complex, were measured. Three of these compounds contain substitutions in the functionally important aldehyde moiety: (i) In one such substitution, the aldehydic hydrogen atom was replaced by a deuterium; (ii) in another, this hydrogen atom was replaced by deuterium, and the aldehydic carbon atom was replaced by 13C; and (iii) in the third derivative, only the carbon atom was replaced by 13C. The fourth derivative has had the two hydrogen atoms at the 3- and 5-positions of the DABA ring replaced by deuterium atoms. We find that many of the spectral modes are fairly extended, involving both stretching and bending motions of the entire molecule, although a few modes are quite localized. We find that the normal mode structure of DABA changes considerably when it binds to LADH/NADH. As a model for the bound DABA, we have examined the zinc complexes of DABA (and all four isotopically labeled samples) in anhydrous diethyl ether and methylene chloride. A striking correspondence between the Raman spectra of the enzyme-bound DABA and DABA-Zn complexes in solution is found, which extends to all the isotopically labeled derivatives. This suggests that one of the major roles of LADH in the binding of DABA is to provide a divalent zinc ion to form a first-sphere Lewis acid complex. The data also suggest other interactions between enzyme-bound DABA with its protein surroundings and with the coenzyme NADH are quite minor. An estimate of the carbonyl bond character of bound DABA had been made on the basis of the response of Raman bands to isotopic labeling and on trends observed in spectra of DABA in solvents of various polarities.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibition of the metabolism of urethane by ethanol

Ethanol has been shown to inhibit the localization of [ethyl-1-14C] urethane in the male mouse, but the effect of ethanol on the metabolism of urethane has not been clarified. Consequently, the concentration of unchanged urethane was determined in the blood of male mice up to 11 hr after oral administration of urethane with or without ethanol. A high and constant blood level of urethane persisted for 8 hr after the administration of an ethanolic solution of [ethyl-1-14C] urethane (125 mumol/kg, 10 muCi/20 g of mouse, 5 g of ethanol per kg, po); the blood level of ethanol was at or above 150 mg/dl during these 8 hr. In contrast, rapid clearance of radioactivity was observed in mice treated with [ethyl-1-14C]urethane dissolved in water. Coadministration of ethanol with urethane decreased the rate of 14CO2 expiration; furthermore, covalent binding with liver protein was delayed about 8 hr and was less than that in the group treated with urethane in water. The metabolism of urethane and production of 14CO2 from [carbonyl-14C]urethane by mouse liver homogenate in vitro were inhibited by the presence of ethanol (greater than 10 mM); these concentrations of ethanol in vitro are about the same as those that are inhibitory in vivo, but the extent of inhibition suggests that the liver is not the only site of metabolism of urethane. These results indicate that ethanol can inhibit the initial metabolism of urethane, prevent the formation of active metabolites, and allow urethane to persist in blood.

Auditory space representation in the inferior colliculus of the FM bat, Eptesicus fuscus

The auditory spatial response areas of 333 inferior collicular (IC) neurons of Eptesicus fuscus were studied under free-field acoustic stimulus conditions. A stimulus was delivered from a loudspeaker placed 14 cm in front of a bat and the best frequency of an encountered neuron was determined. Then a best frequency (BF) stimulus was delivered as the loudspeaker was moved across the frontal auditory space to determine the response center of the neuron. At the response center, the neuron had the lowest minimum threshold. The stimulus was then raised 3-15 dB above the lowest minimum threshold of the neuron and the spatial response area for each stimulus intensity was measured. The response center and spatial response area of a neuron measured with a one-octave downward-sweep FM stimulus were similar to those measured with the pure tone pulse. The spatial response area of a neuron expanded asymmetrically with the stimulus intensity. High BF neurons generally had smaller spatial response areas than low BF neurons had. All 333 response centers were located in the contralateral auditory space. Response centers of low BF neurons tended to be located laterally while those of high BF neurons were located medially. Although each neuron had a point of lowest minimum threshold in the contralateral auditory space, the point-to-point representation of the auditory space was not systematically organized. This representation was not correlated with the recording sites of the neurons in the mediolateral, posteroanterior and dorsoventral axes of the IC.

Recombinational repair of hydrogen peroxide-induced damages in DNA of phage T4

Recently, hydrogen peroxide and its free-radical product, the hydroxyl radical (OH.) have been identified as major sources of DNA damage in living organisms. They occur as ubiquitous metabolic by-products and, in humans, cause several thousand damages in a cell's DNA per day. They are thought to be a major source of DNA damage leading to aging and cancer in multicellular organisms. This raises two questions. First, what pathways are used in repair of DNA damages caused by H2O2 and OH.? Second, a new theory has been proposed that sexual reproduction (sex) evolved to promote repair of DNA in the germ line of organisms. If this theory is correct, then the type of repair specifically available during the sexual process should be able to deal with important natural lesions such as those produced by H2O2 and OH. . Does this occur? We examined repair of hydrogen peroxide damage to DNA, using a standard bacteriophage T4 test system in which sexual reproduction is either permitted or not permitted. Post-replication recombinational repair and denV-dependent excision repair are not dependent on sex. Both of these processes had little or no effect on lethal H2O2 damage. Also, an enzyme important in repair of H2O2-induced DNA damage in the E. coli host cells, exonuclease III, was not utilized in repair of lethal H2O2 damage to the phage. However, multiplicity reactivation, a recombinational form of repair depending on the sexual interaction of two or more of the bacteriophage, was found to repair lethal H2O2 damages efficiently. Our results lend support to the repair hypothesis of sex. Also the homology-dependent recombinational repair utilized in the phage sexual process may be analogous to the homology-dependent recombination which is widespread in diploid eucaryotes. The recombinational repair pathway found in phage T4 may thus be a widely applicable model for repair of the ubiquitous DNA damage caused by endogenous oxidative reactions.

Classical Raman spectroscopic studies of NADH and NAD+ bound to liver alcohol dehydrogenase by difference techniques

We report the Raman spectra of reduced and oxidized nicotinamide adenine dinucleotide (NADH and NAD+, respectively) and adenosine 5'-diphosphate ribose (ADPR) when bound to the coenzyme site of liver alcohol dehydrogenase (LADH). The bound NADH spectrum is calculated by taking the classical Raman difference spectrum of the binary complex, LADH/NADH, with that of LADH. We have investigated how the bound NADH spectrum is affected when the ternary complexes with inhibitors are formed with dimethyl sulfoxide (Me2SO) or isobutyramide (IBA), i.e., LADH/NADH/Me2SO or LADH/NADH/IBA. Similarly, the difference spectra of LADH/NAD+/pyrazole or LADH/ADPR with LADH are calculated. The magnitude of these difference spectra is on the order of a few percent of the protein Raman spectrum. We report and discuss the experimental configuration and control procedures we use in reliably calculating such small difference signals. These sensitive difference techniques could be applied to a large number of problems where the classical Raman spectrum of a "small" molecule, like adenine, bound to the active site of a protein is of interest. The spectrum of bound ADPR allows an assignment of the bands of the bound NADH and NAD+ spectra to normal coordinates located primarily on either the nicotinamide or the adenine moiety. By comparing the spectra of the bound coenzymes with model compound data and through the use of deuterated compounds, we confirm and characterize how the adenine moiety is involved in coenzyme binding and discuss the validity of the suggestion that the adenine ring is protonated upon binding. The nicotinamide moiety of NADH shows significant molecular changes upon binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of late clinical status between patients with different hemodynamic findings after repair of tetralogy of Fallot

Long-term results and postoperative hemodynamic findings were reviewed in 144 cases of tetralogy of Fallot. A correlation was found between the late clinical status of patients and the postoperative hemodynamic findings. The mortality in our series of patients followed for 10 years was 6.25%. Each of the deaths occurred in the group with unsatisfactory postoperative hemodynamic findings. An ideal late clinical result can be anticipated in most patients with excellent or satisfactory postoperative hemodynamic findings. The greater the deviation from normal hemodynamic findings, the worse the prognosis. From the excellent group to the unsatisfactory group, the incidence of late ideal result decreased from 95% to 61.1%, while the incidence of poor result increased from 0% to 27.8%. Among various factors in patients in the unsatisfactory hemodynamic group, right ventricular outflow tract obstruction seems to have the worst late result. A large right ventricular-pulmonary artery pressure gradient was noted in three of four who died suddenly. The late result of patients with a small shunt (pulmonary blood flow/systemic blood flow less than 2) seems acceptable; the decision to reoperate in these patients should be made very cautiously.

Raman spectroscopy of oxidized and reduced nicotinamide adenine dinucleotides

We have measured the Raman spectra of oxidized nicotinamide adenine dinucleotide, NAD+, and its reduced form, NADH, as well as a series of fragments and analogues of NAD+ and NADH. In addition, we have studied the effects of pH as well as deuteration of the exchangeable protons on the Raman spectra of these molecules. In comparing the positions and intensities of the peaks in the fragment and analogue spectra with those of NADH and NAD+, we find that it is useful to consider these large molecules as consisting of component parts, namely, adenine, two ribose groups, two phosphate groups, and nicotinamide, for the purpose of assigning their spectral features. The Raman bands of NADH and NAD+ are found generally to arise from molecular motions in one or another of these molecular moieties, although some peaks are not quite so easily identified in this way. This type of assignment is the first step in a detailed understanding of the Raman spectra of NAD+ and NADH. This is needed to understand the binding properties of NADH and NAD+ acting as coenzymes with the NAD-linked dehydrogenases as deduced recently by using Raman spectroscopy.

Induction of sIg-negative B lymphocytes for differentiation by PWM

It has been reported in the literature that PWM-responsive B lymphocytes are sIgM+, sIgD-, lack receptors for mouse erythrocytes, and are larger than PWM-negative lymphocytes. This paper describes the observation of B cells among the thymocytes from a patient with myasthenia gravis. In the thymocytes, actually no sIg+ cell was found, and Staphylococcus aureus Cowen strain I could not induce the mononuclear cells in the thymus to differentiate. It was surprising that 6.9 per cent of the cells were BA-1 positive cells. At the same time, in the presence of PWM, 9680 +/- 555 cells out of 1 X 10(-6) thymocytes could be induced to differentiate to immunoglobulin-secreting cells (ISC) in culture. This result suggests that PWM might be able to induce sIg- B lymphocytes to differentiate as well.

Study on the effect of calf thymic peptides preparation (TP) on human B lymphocytes

Extensive experimental evidence has shown that thymic hormones (or factors) affect and regulate the differentiation and function of T lymphocytes. However, little is known about the action, if any, of thymic hormones on B lymphocytes. This paper reports the results of an investigation of the effect of a calf thymic peptide preparation (TP) prepared in our laboratory, on the proliferation and differentiation of human B lymphocytes. TP at concentrations higher than 1 micrograms (protein)/ml inhibited the proliferative responses of human B lymphocytes to the stimulation by Staphylococcus aureus Cowen strain I (SAC) and F(ab')2 fragments of goat anti-human IgM, mu chain specific antibody (anti-mu). TP itself had neither toxic nor mitogenic effect on B cells. TP at concentrations of 60 and 100 micrograms/ml did not affect the differentiation of B cells driven by SAC and PWM in a reverse PFC assay, but appeared to suppress the production in some individuals of total IgG and IgM in culture supernatants in a PWM system. Preculture of B cells with 60 micrograms/ml of TP for 40 hrs showed a suppression of the proliferative response to SAC and anti-mu stimulation, suggesting that TP might act on cells directly and persistently for some time. When TP was added to the culture on day 0 or on day 1, a similar decrease of inhibition of B cell proliferation was observed. A decrease in monocytes from 15-17% to 5% did not appreciably influence the suppression of SAC- or anti-mu-induced proliferation of B cells by TP. These preliminary results suggest that a calf thymic peptides preparation might have some direct effect on B lymphocytes.

A potent converting enzyme inhibitor CGS 13928C. Drug profile in normal volunteers

The converting enzyme inhibitor CGS 13928C was evaluated in 15 healthy male volunteers. First the efficacy of a single oral dose of 0.5, 1, 2 or 5 mg in antagonizing the pressor response to exogenous angiotensin I was tested with continuous monitoring of the blood pressure and heart rate by an intraarterial catheter. CGS 13928C 1, 2 and 5 mg consistently reduced the response to angiotensin within 2 to 3 h and for a period exceeding the 4 h of monitoring. The 2 mg dose was hardly more effective than 1 mg and 5 mg did not further enhance the blockade. Subsequently, plasma renin and converting enzyme activity, angiotensin I, angiotensin II and aldosterone were measured serially before and up to 72 h following oral administration of either 1 mg (n = 7) or 2 mg (n = 8) CGS 13928C. As expected, plasma renin activity and angiotensin I rose, while plasma converting enzyme activity, angiotensin II and aldosterone fell following both doses of the drug. No side-effects occurred. In normal volunteers CGS 13928C is an effective and extremely potent, orally active converting enzyme inhibitor.

Prosthetic auricular reconstruction

Large lesions may necessitate resection of critical amounts of auricle, such that surgical reconstructive efforts may prove to be futile. We favor the prosthetic rehabilitation of patients requiring near total auriculectomy. Fifteen patients seen for the treatment of auricular lesions from 1976 to the present were reviewed. Near total auriculectomy with postoperative prosthetic management provided satisfactory functional and aesthetic results. This presentation will highlight the significant technical features of the surgical ablation and subsequent prosthetic management of patients with tumors of the auricle, such that postoperative rehabilitation will be facilitated.

Kinetic characteristics of bicarbonate-chloride exchange across the neonatal human red cell membrane

The kinetics of HCO-3/Cl- exchange across red cell membrane of newborn infants was studied using a stopped-flow rapid reaction apparatus with a glass pH electrode attached. The measured apparent permeability P is (1.35 +/- 0.08 (S.E.)). 10(-4) cm/s (n = 30) for newborns, compared with (3.1 +/- 0.4) . 10(-4) cm/s (n = 15) for adults. These correspond to half-times of 0.2 s for newborns and 0.1 s for adults indicating that neonatal red cells exchange Cl- for HCO-3 only half as fast as do adult cells. The temperature dependence of the exchange rate was studied from 2 to 42 degrees C. From the Arrhenius plot the activation energy of the exchange process in neonatal red cells changes from 22.9 kcal/mol (low temperature) to 4.8 kcal/mol (physiological temperature) at a transition temperature of 17 degrees C. These values are lower than the corresponding values for adult red cells, 34.7 and 10.2 kcal/mol. HCO-3/Cl- exchanges in both adult and neonatal red cells are inhibited by phlorizin. Inhibition constants Ki are 0.8 mM and 2.5 mM for adults and newborns, respectively. The differences in the value of the HCO-3/Cl- exchange rate constant and the activation energy of the exchange process between neonatal and adult red cells indicate that there is a modification of HCO-3/Cl- transport system in the neonatal red cell membranes.

Current status of radionuclide scrotal imaging

Scrotal imaging with technetium-99m sodium pertechnetate consists of a radionuclide angiogram and static scrotal scans. Utilization of this study in patients presenting with an acute scrotum can dramatically reduce the number of surgical explorations for acute epididymitis. It can also aid in other aspects of differential diagnosis in patients presenting with either an acutely enlarged and/or painful scrotum or a scrotal mass. Ambiguities in previous descriptions of perfusion through the spermatic and extraspermatic cord vessels are described and distinguished from scrotal perfusion. The clinical and scintigraphic spectrum of testicular torsion, including spontaneous detorsion, early acute testicular torsion, midphase testicular torsion, and late phase or "missed testicular torsion," is discussed and illustrated. The variety of patterns seen in acute epididymitis, including lateral and medial epididymal location, and focal epididymitis are described, as is the appearance of hydrocele as both a primary and secondary entity. The relationship of scrotal imaging to the overall clinical presentation and evaluation of these patients is emphasized in testicular torsion, torsion of the testicular appendages, epididymitis, abscess, trauma, tumor, spermatocele, and varicocele. The techniques, clinical utility, and relationship to radionuclide imaging of Doppler ultrasound and gray scale ultrasound scanning are reviewed. Doppler ultrasound results in many false negative studies in testicular torsion. Gray scale ultrasound is useful in clarifying the nature of scrotal masses.

Inhibitor of peritoneal mononuclear phagocyte colony forming cells

We investigated an inhibitory factor present in mouse L-cell conditioned medium. This soluble factor, colony inhibitory factor (CIF), selectively inhibits the clonal growth of mouse peritoneal exudate (PE) macrophages in vitro. CIF appears to be a non-dialyzable macromolecule which was eluted by Sephadex G200 gel filtration at post-albumin fractions. It can be fractionated by ammonium sulfate precipitation within the range of 60%--70% saturated solution at room temperature. CIF is moderately heat labile and is destroyed by incubation at high pH. CIF is more effective on PE cells from C57 mice than on those from C3H or DBA mice. It also inhibits the clonal growth of committed stem cells for both granulocytes and macrophages present in bone marrow but to a much lesser degree. CIF is not interferon since no antiviral activity is demonstrable in the CIF preparation.

Neuromuscular block by antibiotics: polymyxin B

Characteristics of neuromuscular block produced by polymyxin B (PXB) were examined in 12 anesthetized cats, using sciatic nervetibialis anticus muscle preparations. The ED50 was 6.7 (+/- 1.4, SD) PXB base/kg body weight. The ED95 was 10.8 (+/- 2.4) mg/kg. Spontaneous recovery from 25 percent of control to 75 percent of control required 72 (+/- 16) minutes. During a 50 percent block, train-of-four twitches elicited at 2 Hz faded with a train-of-four ratio of 0.42 (+/- 0.13), but the tetanus did not fade. Edrophonium Cl, neostigmine methylsulfate, and pyridostigmine Br at sub-clinical dosages weakly antagonized the block but enhanced the block at anti-curare dosages. All 3 cholinesterase inhibitors were short acting, lasting 10 to 15 minutes, and noncumulative on repeated injection. The potency ratio was approximately 20:10:1 in the order of edrophonium, neostigmine, and pyridostigmine on a weight-for-weight basis. Calcium partially antagonized the block. The authors conclude that neuromuscular blocks produced by various antibiotics differ from each other and from that produced by other groups of neuromuscular blocking agents, including curare.

Characteristics of nondepolarizing neuromuscular block: (I) post-junctional block by alpha-bungarotoxin

The characteristics of neuromuscular block produced by alpha-bungarotoxin, a post-junctionally active polypeptide toxin purified from snake venoms, have been studied in vivo in 12 anaesthetized cats, using the sciatic nerve-tibialis anterior muscle preparation. The onset of the neuromuscular block was slow and without fasciculation. The block was persitently progressive. The time course of the block depended on the dosage. In general, 0.1 mg/kg of alpha-BuTX appeared to approximate the threshold dosage while 0.2 mg/kg completely eliminated the twitch response in 2-5 hours. No recovery was observed in 8-30 hours. Larger doses accelerated the progression of the block. During the block, tetanic contractions and train-of-four twitches did not fade. The post-tetanic twitches were markedly facilitated. The block was antagonized by edrophonium, neostigmine, pyridostigmine, and succinylcholine, but the antagonism was less effective and shorter-lasting than that observed on curare-block, and the block always resumed the projected progression. Attempts were made to explain the observed difference between alpha-BuTX- and dTc-induced neuromuscular blocks by the practically permanent nature of block and the purely post-junctional site of action of alpha-BuTX. It was concluded that a pure post-junctional block is not characterized by fade, which rather might be a pre-junctional effect of some nondepolarizing neuromuscular blocking agents like d-tubocurarine.

Neuromuscular block by neomycin in the cat

The neuromuscular block produced by neomycin is unique. Despite nearly complete blockade of the twitch the tetanus is not blocked and does not fade. The pathognomonic post-tetanic exhaustion has not been reported previously. Anticholinesterases and calcium antagonize the block, but the antagonism may not be complete. Germine antagonizes the block in the cat, but its clinical value has not been tested. These characteristics of neuromuscular block by neomycin strongly suggest respiratory support and sedation to decrease the respiratory drive, rather than attempts at antagonism, as the rational management of patients suffering from toxic paralysis due to neomycin.

Spontaneous recovery of the thumb twitch from neuromuscular block by suxamethonium in anaesthetized man

The neuromuscular blocking effect of repeated bolus administration of suxamethonium 1 mg/kg was observed in 10 healthy surgical patients under enflurane-nitrous oxide-oxygen anaesthesia. Tachyphylaxis and slow recovery of the thumb twitch occurred in close dose-relationships with transition of Phase I block to Phase II, using train-of-four fade as an indicator of the transition. Failure of the thumb twitch to recover to 75% of control, and subsequent step-wise depression from additional doses of suxamethonium had a sudden onset shortly after establishment of marked train-of-four fade.

De Novo Biosynthesis of Deoxyribonucleic Acid Polymerase during Wheat Embryo Germination

An 8-fold enhancement in the activity of a DNA-dependent DNA polymerase was found in extracts from germinating wheat (Triticum vulgare var. Florence) embryos, as compared to the activity found in extracts from ungerminated embryos. The enhancement of this activity during the first hours of germination is concomitant to the increase of a Dnase activity. The two activities could be separated and the increased level of the DNA polymerase upon germination was observed in an enzymatic fraction which contains very low DNase activity. Addition of the protein synthesis inhibitor, blasticidin S, to germinating wheat embryos, reduced the increase in DNA polymerase. Incorporation of radioactive amino acids into a phosphocellulose preparation, which contains the DNA polymerase starts during the first 6 hours of germination. The amount of radioactivity incorporated is doubled in the next 6 hours, and the incorporation is continued between 12 and 18 hours of germination.

Offset prism for optical waveguide coupling

High refractive index prisms have been used to couple optical beams into the thin film waveguides. To scan through various propagating modes normally requires rotating and repositioning of the prism-waveguide assembly. We have found that the required adjustment of the prism-position can be eliminated during the scanning of the various modes if the prism is properly offset with respect to the rotational axis. An analysis and a computer program are given for the calculation of this prism offset position on the basis of minimum deviation within the specified limits of the prism rotational angle.

Subnanosecond Laser Recording on MnBi Thin Films

Thermomagnetic writing and erasure of binary information in MnBi thin films using 250-psec pulses are described. The ability to write with such short pulses could greatly improve data rates in optical memories. Repeated cycling of a single spot gave inconclusive results concerning possible retardation or inhibition of phase change in MnBi for very short heating pulses.

Magnetic materials for optical recording

Optical digital data storage using magnetic materials offers the combined advantages of magnetic recording and beam addressable technique. Recent progress in this technology is reviewed.