Developmental transitions in the myosin patterns of two fast muscles

Transitions in myosin patterns were examined in situ by immunofluorescence in two fast muscles of the developing chicken, the pectoralis and the posterior latissimus dorsi. Myosin isoforms were localized using stage-specific monoclonal antibodies against the heavy chain of pectoralis myosin. Two antibodies (12C5 and 10H10) recognize adult and late embryonic myosin. They reacted weakly with both the pectoralis and posterior latissimus dorsi at 10 days in ovo, but intensely at 18 days in ovo. Both muscles were completely unreactive with an adult-specific antibody (5C3), indicating that the staining with 12C5 and 10H10 at 18 days in ovo reflects embryonic myosin. Thus two different embryonic isoforms are expressed sequentially in each muscle. Both 12C5 and 10H10 reacted weakly again with these muscles after hatching. The reappearance of a strong positive response to both antibodies, at 28 days in the pectoralis and after 60 days in the posterior latissimus dorsi, correlated well with the first appearance of a response to the adult-specific antibody, 5C3, signalling the beginning of the adult pattern. Both muscles reacted strongly with an antibody (5B4) specific for 'neonatal' myosin between 18 days in ovo and 60 days after hatching. In the pectoralis, embryonic was replaced by neonatal myosin in most fibres by 14 days after hatching; by 28 days, both adult and neonatal myosin were expressed in most fibres; and in the adult, neonatal myosin was replaced entirely by the adult isoform. In contrast, many fibres in the posterior latissimus dorsi still expressed both embryonic and neonatal myosins up to at least 60 days post-hatch, and the remaining fibres expressed the neonatal isoform; the neonatal isoform was present in some fibres even in the adult posterior latissimus dorsi. We have therefore demonstrated in situ four different heavy chain isoforms in two different fast muscles. 'Early embryonic', 'late embryonic', 'neonatal' and eventually 'adult' isoforms are expressed in each muscle and more than one isoform often coexists in the same fibre.     

Induction of endolymphatic hydrops in the guinea pig by perisaccular deposition of sepharose beads carrying and not carrying immune complexes

Click-evoked auditory brainstem responses were recorded in a prosimian primate, the bush baby (Otolemur garnettii), before and after depletion of serotonin (by systemic injection of para-chlorophenylalanine; pCPA) and up to 20 days after discontinuing pCPA injections (during the recovery of serotonin). Biphasic 100 micros clicks were presented at five repetition rates (13.2, 33.2, 53.2, 73.2, and 93.2 clicks/s; RATE) and sound pressure levels (SPL) were varied in 10 dB steps from 120-60 dB SPL peak equivalent. Absolute latencies of vertex-positive peaks I, III, IV, and V were measured from click onset. The latencies from each wave were statistically analyzed with a two-way analysis of variance using either RATE or SPL (but not both) and TIME AFTER pCPA as independent variables. Prior to pCPA, brainstem response latencies increased as a function of both decreasing SPL and increasing RATE. After pCPA, these normal increases in wave latency increased even more, particularly in response to high click rates. After pCPA was discontinued, measurements taken at weekly intervals indicated that latencies decreased after 1 week, increased to the highest values recorded after 2 weeks, and returned to normal after 3 weeks. These dynamic changes were interpreted to be the result of postsynaptic receptor up-regulation during the 10 days of continuous pCPA administration. These results suggest that serotonin plays an important role in sensory processing at the cellular level and, tonically, facilitates the auditory brainstem response to sound.     

Effects of acute hyperinsulinemia on VLDL triglyceride and VLDL apoB production in normal weight and obese individuals

The effects of short-term hyperinsulinemia on the production of both VLDL triglyceride and VLDL apoB were determined semiquantitatively before and during a 6-h euglycemic hyperinsulinemic clamp (40 mU.m-2 x min-1) in 17 women (8 chronically hyperinsulinemic obese, BMI = 35.7 kg/m2; 9 normal weight, BMI = 22.5 kg/m2). During acute hyperinsulinemia, plasma FFA decreased by approximately 95% within 1 h in both groups. VLDL triglyceride production decreased 66% in the control subjects (P = 0.0003) and 67% in obese subjects (P = 0.0003). ApoB production decreased 53% in control subjects (P = 0.03) but only 8% in obese (NS). Plasma triglycerides decreased by 40% from baseline in control subjects (P < 0.0001) but only by 10% in obese subjects (P = NS). Despite the similar decrease in triglyceride and apoB production in control subjects, VLDL particle size (triglyceride-to-apoB ratio) decreased with hyperinsulinemia (P = 0.003). In obese subjects, despite a decrease in triglyceride production similar to that in control subjects but no change in apoB production, VLDL size did not change appreciably. Acute hyperinsulinemia in humans: 1) suppresses plasma FFA equally in control and obese subjects at this high dose of insulin; 2) inhibits VLDL triglyceride production equally in control and obese subjects, perhaps secondary to the decrease in FFA; 3) inhibits VLDL apoB production in control but less so in obese subjects, suggesting that obese subjects may be resistant to this effect of insulin; 4) decreases plasma triglyceride and VLDL particle size in control subjects, reflecting either stimulation of LPL activity or a greater relative decrease in triglyceride to apoB production; and 5) does not decrease plasma triglyceride or VLDL size in obese subjects to the same extent as it does in control subjects. Thus, the insulin resistance of obesity affects some but not all aspects of VLDL metabolism.     

True aneurysm of the profunda femoris artery. Case report and literature review

The birth of the first cloned mammals, produced by the introduction of somatic cell nuclei into enucleated oocytes, was an impressive and surprising development. Although the ethical debate has been intense, the important scientific questions raised by this work have been inadequately discussed and are still unresolved. In this essay we address three questions about nuclear transplantation in the eggs of mice and domestic animals. First, why were the recent experiments on somatic cell cloning successful, when so many others have failed? Second, were these exceptional cases, or is somatic cloning now open to all? Third, what are the future possibilities for increasing the efficiency and wider applicability of the cloning process?     

The Electronic Spectrum of Gaseous CoO in the Visible Region

Laser excitation spectra of gaseous CoO have been recorded using Doppler-limited intracavity spectroscopy and supersonic jet-cooled molecular beam methods. As seen in the molecular beam spectra there are nearly 100 bands arising from the X4Delta7/2 spin component of the ground state in the wavelength region 430-720 nm. All of them are very strongly red-degraded and most of them are perturbed. 59Co hyperfine broadenings or splittings have been observed in many. The bands can be arranged into five electronic transitions, together with a considerable number of "extra" bands induced by perturbations; two of the excited electronic states are 4Phi, while the other three, which lie within 1700 cm-1, are 4Delta. Semi-empirical calculations have been carried out for the 4Delta excited states, using exchange integrals transferred from the TiO and VO spectra; the predicted energies, spin-orbit structures, and relative intensities in absorption are consistent with the assignment of all three 4Delta states to the same electron configuration, (4ssigma)1(3ddelta)3(3dpi)2(3dsigma)1. It seems that there are extensive interactions between the excited 4Delta states, because only one of them gives rise to a recognizable, though irregular, long vibrational progression in absorption. The other two progressions die out abruptly and unexpectedly after three or four members, presumably as a result of interference effects; however, wavelength-resolved fluorescence studies, together with calculations of the Franck-Condon overlap integrals to the various vibrational levels of the ground state, show that the upper state progressions reappear following a region of confused absorption. All of the excited states show highly irregular variations of their vibrational intervals and rotational constants with the vibrational quantum number, v. The wavelength-resolved fluorescence spectra give evidence for new low-lying electronic states of CoO at 3038, 5989, and 9105 cm-1; based on its vibrational frequency the 3038 cm-1 state is possibly the sigmadelta4pi2 B4Sigma- state. Copyright 1997 Academic Press. Copyright 1997Academic Press     

Differences in the liability to self-administer intravenous cocaine between C57BL/6 x SJL and BALB/cByJ mice

Application of animal models of psychostimulant abuse for experimentation in mice is becoming increasingly important for studying the contribution of genetic differences, as well as the roles of selected (targeted) genes, in specific behaviors. The purpose of this study was to investigate strain differences in cocaine self-administration behavior between C57BL/6 x SJL hybrid mice and BALB/cByJ mice. These two strains were chosen because BALB/cByJ mice have a well-developed behavioral pharmacological profile, and hybrid strains on a C57BL/6 background are commonly used for generating transgenic expressing and knockout mutant mice. C57BL/6 x SJL mice dose-dependently acquired cocaine self-administration (1.0 mg/kg/injection but not 0.25 mg/kg/injection) by responding selectively in the active nose-poke hole and maintaining stable levels of daily drug intake; they also exhibited a characteristic inverted-U-shaped cocaine dose-effect function. BALB/cByJ mice failed to acquire cocaine self-administration at either dose under the same test conditions. The strain differences observed in self-administration did not seem to be attributed to other behavioral differences because the two strains exhibited similar amounts of spontaneous nose-poking in the absence of reinforcers, and BALB/cByJ mice responded more than C57BL/6 x SJL mice in a food-reinforced nose-poke operant task. Importantly, the dose-effect function for the motor stimulating effects of cocaine (3.8-30 mg/kg intraperitoneally) suggests enhanced sensitivity but reduced efficacy of cocaine in stimulating motor activity in BALB/cByJ mice relative to the C57BL/6 x SJL hybrid mice. These results indicate that the decreased liability of BALB/cByJ mice to acquire cocaine self-administration is not the result of differences in spontaneous activity or performance, but may reflect different sensitivities to the reinforcing, or rate-disrupting, properties of cocaine. The data support an influence of genetic background in the liability to self-administer cocaine. Thus, a hypothesis is proposed that the decreased liability of BALB/cByJ mice to acquire cocaine self-administration is related to differences in brain monoamine systems linked to the high "emotionality" profile of BALB/c mice in novel or fearful situations, including perhaps cocaine administration.     

Inhibitory effect of alkylating modulators on the function of P-glycoprotein

Modulators of P-glycoprotein (P-gp) are often themselves transported out of cells, thereby limiting their effectiveness. It may be possible to develop more effective modulators of multidrug resistance by designing drugs that irreversibly block the function of P-gp. Therefore, we studied the effect of the mustard derivatives of fluphenazine (FPN) and trans-flupenthixol (FPT) on P-gp function. Both fluphenazine-mustard (FPN-M) and trans-flupenthixol-mustard (FPT-M) possessed alkylating activity, as assayed using 4-(p-nitrobenzyl) pyridine. Multidrug-resistant MCF-7/AdrR cells were incubated with FPN or FPN-M, or FPT or FPT-M for 1 h, washed for varying number of times in phosphate-buffered saline (PBS), then resuspended in medium containing [3H]vinblastine (VBL), and assayed for steady-state accumulation of the drug. Washing had far less of an effect on the ability of FPN-M and FPT-M to increase VBL accumulation compared to their parent compounds. After eight washes in excess PBS, the cells initially exposed to FPN or FPT accumulated only 30% and 50% of the initially accumulated drug, whereas the FPN-M- or FPT-M-treated cells accumulated approximately 75% and 90% of the control, respectively. FPN-M and FPT-M also increased the uptake and decreased the efflux of VBL from MDR cells despite repeated washing. We also examined the effects of these modulators on sensitivity of MDR cells to cytotoxic agents. FPN-M and FPT-M sensitized MCF-7/AdrR cells to VBL and doxorubicin to a greater extent than their parent compounds. These studies point out the potential of "irreversible" P-gp modulators to produce prolonged chemosensitization.