Heat shock affects cell cycling in the neural plate of cultured rat embryos: a flow cytometric study

The effects of heat shock on cell cycling in the mammalian neuroectoderm were determined by applying heat shocks to cultured rat embryos at the neural plate stage, as part of a study on the teratogenic effects of heat shock on neural development. The heat shocks had been characterized previously (Walsh et al.: Teratology 36:181-191, 1987) with respect to their effects on the gross morphological development of the rat embryos. The effects on cell cycling were observed in DNA histograms of neural plate cells recorded in a flow cytometer after staining with DAPI. The mild heat shock (42 degrees C for 10 min) arrested cells at entry to S phase. The teratogenic heat shock (43 degrees C for 7.5 min) arrested cells at entry to S phase also but for a longer time and inhibited cycling through S phase. After each arrest, a synchronized peak of cells later entered S phase and progressed through the cycle. The induced-thermotolerance heat shock, which was the mild heat shock followed after an interval by the teratogenic heat shock, showed that pre-treatment with the mild heat shock reduced the magnitude of the response to the teratogenic heat shock. The cell-cycle inhibitor ICRF 159 showed the effects on cycling rates of the heat-shock treatments. The arrest of cells at entry to S phase by heat shock may function to prevent cells entering DNA synthesis under non-optimal conditions. We report estimates of proportions of non-proliferative cells in the neural plate of the rat embryos.     

Wound closure of the myelomeningocoele defect

Our experience with 74 neonates with myelomeningocoele is reported. Management in the first phase of the study period consisted of primary closure in 37 patients by wide undermining and skin advancement, marked by a high wound-complication rate. Latissimus dorsi muscle closure, either "reverse" or advanced, was performed in a transitional phase in 5 patients, characterized by increased operative time and blood loss. In the last portion of the study period, 32 patients were managed by immediate dural closure and skin grafts either simultaneously or on a delayed basis at 48 to 72 hours with a low incidence of graft loss, CSF leak, or sepsis. Back ulceration and follow-up in either the primary closure or the skin-grafted group has been infrequent.     

Morphologic changes of the pancreas in hemorrhagic shock and the postresuscitation period

The canine pancreas (20) in the terminal period of hemorrhagic shock and postresuscitation period was studied histologically and electronmicroscopically. There were detected ultrastructural signs of the plasmatic membranes of pancreatocytes and membranes of secretory granules with "leakage" of pancreatic ferments in the interstitial tissue. The incretion of pancreatic ferments in the vascular bed is conditioned by the elevation of proteolytic activity of blood serum in hemorrhagic shock and postresuscitation period.     

Characterization of the heat shock response inEnterococcus faecalis

We have characterized the general properties of the heat shock response of the Gram-positive hardy bacteriumEnterococcus faecalis. The heat resistance (60°C or 62.5°C, 30 min) of log phase cells ofE. faecalis grown at 37°C was enhanced by exposing cells to a prior heat shock at 45°C or 50°C for 30 min. These conditioning temperatures also induced ethanol (22%, v/v) tolerance. The onset of thermotolerance was accompanied by the synthesis of a number of heat shock proteins. The most prominent bands had molecular weights in the range of 48 to 94kDa. By Western blot analysis two of them were found to be immunologically related to the well known DnaK (72 kDa) and GroEL (63 kDa) heat shock proteins ofEscherichia coli. Four other proteins showing little or no variations after exposure to heat are related to DnaJ, GrpE and Lon (La)E. coli proteins and to theBacillus subtilis ⁴³ factor. Ethanol (2% or 4%, v/v) treatments elicited a similar response although there was a weaker induction of heat shock proteins than with heat shock.     

Some Ultrastructural Changes Induced in Resistant and Susceptible Soybean Roots Following Infection by Rotylenchulus reniformis

A developmental electron microscopic study of the parasitism of Rolylenchulus reniforrnis in resistant ''Peking'' and susceptible ''Lee'' soybeans was made during a 21-day period under controlled conditions. Within 2 days of inoculation, the nematode had penetrated the cortical cells to the endodermis where it inserted its stylet, secreted and initiated syncytial formation and cell hypertrophy. Syncytia primarily involved pericycle tissues and, to a lesser extent, xylem parenchyma and endodermis. When identifiable, the cell into which the nematode stylet was inserted to initiate syncytial development was endodermal. Susceptible tissues exhibited two basic phases of development during this infection period: (i) an initial phase represented by partial cell wail lysis and separation; and (ii) an anabolic phase, characterized by organelle proliferation and development accompanied by secondary wall deposits, which provided nutrition for sessile female development. The resistant or hypersensitive reaction (HR) lacked the anabolic phase found in the susceptible reaction, and was characterized by an extension and usually accelerated type of Iysis found in the first phase of the syncytial development. The HR was usually very evident 4 days after inoculation, and could be identified by an almost complete lysis of the cell walls and cytoplasm. The possibility that the initial cell of the developing syncytium or "prosyncyte" may influence a susceptible or resistant reaction is discussed. Successive stages of cell wall dissolution and the deposition of secondary cell walls are described.     

Characterization of purified avian 90,000-Da heat shock protein

The so-called 90,000-Da heat shock protein (hsp90) from chicken liver has been purified and physically characterized in the presence of high levels of the serine phosphatase inhibitor fluoride. The protein is an elongated dimer with a molecular weight of 160,000 and a frictional ratio of 1.6. On two-dimensional electrophoresis it exhibits several isoelectric forms lying between pH 5.1 and 5.8. It contains an average of 5.8 mol of covalently bound phosphate per dimer and is thus extensively phosphorylated. Analysis of the ultraviolet spectrum showed the purified protein to be free of nucleotide-containing components. Molybdate has been shown to stabilize complexes between the 90,000-Da heat shock protein and steroid receptors. However, molybdate has no effect on the sedimentation of the purified heat shock protein. Proteins structurally related to hsp90 have been reported to penetrate the endoplasmic reticulum. However, when purified hsp90 was tested using the partition method of Bordier, which distinguishes hydrophilic and lipophilic proteins, it partitioned totally into the aqueous phase.     

Features of the morphofunctional response of Peyer's patches in rats during the course of traumatic shock and the early post-shock period

The reaction of Peyer's patches to trauma manifests in: 1) vascular changes; 2) primary or stressor cells shifts recordable in traumatic shock, characterized by depletion of patch follicles by minor lymphocytes; 3) secondary changes associated with the onset of reparative processes; 4) the increased macrophagal activity detectable during the entire period of the traumatic shock and in the early post-shock period. It is suggested that changes seen may be due to endotoxin that penetrates from the intestine.     

Physiological diversity and trehalose accumulation in Schizosaccharomyces pombe strains isolated from spontaneous fermentations during the production of the artisanal Brazilian cachaça

Twenty-seven Schizosaccharomyces pombe isolates from seven cacha?a distilleries were tested for maximum temperature of growth and fermentation, osmotolerance, ethanol resistance, invertase production, and trehalose accumulation. Two isolates were selected for studies of trehalose accumulation under heat shock and ethanol stress. The S. pombe isolates were also characterized by RAPD-PCR. The isolates were able to grow and ferment at 41 degrees C, resisted concentrations of 10% ethanol, and grew on 50% glucose medium. Four isolates yielded invertase activity of more than 100 micromol of reducing sugar x mg(-1) x min(-1). The S. pombe isolates were able to accumulate trehalose during stationary phase. Two isolates, strains UFMG-A533 and UFMG-A1000, submitted to a 15 min heat shock, were able to accumulate high trehalose levels. Strain UFMG-A533 had a marked reduction in viability during heat shock, but strain UFMG-A1000 preserved a viability rate of almost 20% after 15 min at 48 degrees C. No clear correlation was observed between trehalose accumulation and cell survival during ethanol stress. Strain UFMG-A1000 had higher trehalose accumulation levels than strain UFMG-A533 under conditions of combined heat treatment and ethanol stress. Molecular analysis showed that some strains are maintained during the whole cacha?a production period; using the RAPD-PCR profiles, it was possible to group the isolates according to their isolation sites.     

Marathon related death due to brainstem herniation in rehydration-related hyponatraemia: a case report

Introduction

The natural history of patients with spontaneous parathyroid necrosis is unknown. In this case report we describe the clinical course, laboratory, radiographic, bone densitometry tests, parathyroid ultrasonography and scintigraphy examinations of a patient performed over a period of eight years after she first presented with a sudden episode of spontaneous resolution of primary hyperparathyroidism (PHPT).

Case presentation

A 24-year-old woman with a clinical history and laboratory and radiographic tests compatible with PHPT suffered a sudden episode of cervical pain and presented with clinical evidence of hypocalcemia. Biopsy of a cervical nodule revealed necrotic material compatible with ischemia of the parathyroid. The follow-up of the patient presented four distinct phases: the first, which lasted two years, was compatible with a period of bone hunger during which it was necessary to introduce calcitriol and calcium carbonate. During this period, the patient showed bone mass gain. The second phase was characterized by normalization of calcium and parathyroid hormone levels and its end was difficult to define. During the third phase there was a recurrence of hypercalcemia associated with elevated parathyroid hormone (PTH) levels and loss of bone mass. The last phase corresponded to the interval after parathyroidectomy, which was characterized by normalization of serum levels of calcium and PTH, as well as bone mass gain.

Conclusion

This case report indicates that spontaneous resolution of PHPT by adenoma necrosis is potentially temporary. Thus, in cases in which a conservative approach is chosen, clinical and laboratory follow-up is indispensable. Bone mass measurement is a useful tool in the follow-up of these cases. However, this option exposes the patient to a potential roller-coaster ride of bone mass gain and loss, whose long term consequences are still unknown.     

Microcirculatory disorders in the connective tissue structures of certain organs in traumatic shock with acute hemorrhage]

The present work is a fragment of the author's complex study of replantation of an extremity in experiment. Experiments on reproduction of the model of traumatic shock with acute loss of blood under conditions of muscle relaxation proposed by Yu. V. Kiprenski were performed in 15 dogs and 10 cats. It was established that in animals dead as a result of shock there appeared severe disorders of microcirculation in tissues and organs. They were characterized by a pronounced spasm of the vessels of the arteriolar link and dilatation of the venular and lymph collectors of the microcirculation bed. Simultaneously a great number of arterio-venular anastomoses were opened through which the arterial blood was shunted partly to avoid constricted capillaries. In the vessels of the venular link of the microcirculatory bed there appeared aggregations of formed elements of blood and microemboles. In absence of specific complex therapy, as it was in our experiments, the animals die of shock within the period from 17 min to 5 hour 20 min.     

Further experiments on the conditioning and pseudoconditioning of the tarsal reflex in the drosophila (Drosophila melanogaster): effect of low intensity electric shocks]

In a recently described procedure of negative instrumental conditioning, applied to the tarsal reflex of Drosophila (Médioni and Vaysse, 1975), it was attempted to eliminate some "noise" sources superimposed on the associative conditioning effect. 1) By increasing the preliminary reiteration of the sugar stimulus (US for the tarsal reflex), the suppressive influence of "desensitization" (i.e. sensory adaptation and/or central habituation) could be minimized, at least in the first 20 trials of the training phase. 2) By lowering the intensity of the electrical shock used as an aversive reinforcer, the pseudo-conditioning rate could be substantially reduced too. However the relative weight of the pseudoconditioninq effects could not be decreased by these means: for the effectiveness of the mild shock became weaker for the "true" conditioning as well.     

Attenuation of sepsis-induced apoptosis by heat shock pretreatment in rats

Apoptosis is a process by which cells undergo a form of non-necrotic cellular suicide. Although it is a programmed process, apoptosis can be induced by various stressors. During sepsis, apoptosis has been regarded as an important cause of cell death in the immune system, leading to unresponsiveness to treatment. This study was designed to investigate how prior heat shock induction can influence the rate of apoptosis in animals that have experienced sepsis. Sprague-Dawley rats were used, and experimental sepsis was induced by cecal ligation and puncture (CLP). Animals in the heated group were anesthetized and received heat shock by whole-body hyperthermia. They were sacrificed 9 h and 18 h after CLP as early and late sepsis, respectively. Apoptosis was evaluated by "DNA ladder" detection in agarose electrophoresis and Tdt-mediated dUTP nick end-labeling (TUNEL) assay. Hsp72 was detected by Western blot analysis. The results showed that the DNA ladder was detected most clearly in the thymus at the late phase of sepsis with time course dependence, while it showed less clearly in heat shock treated animals. Histopathological study by TUNEL assay obtained similar results in the thymus, where the cortex was more susceptible to apoptosis than the medulla. The Western blot analysis showed that the heat shock induced Hsp72 concomitant with an increase in Bcl-2:Bax ratio. In conclusion, heat shock pretreatment prevents rats from sepsis-induced apoptosis that may account for the better outcome of experimental sepsis. An increase in the Bcl-2:Bax ratio may in part explain the molecular mechanism of the effect of heat shock pretreatment.     

High-level Constitutive Expression of α1-acid Glycoprotein and Lack of Protection Against Tumor Necrosis Factor-induced Lethal Shock in Transgenic Mice

1-Acid glycoprotein (AGP) is an acute phase protein produced by hepatocytes. Although its exact biological function remains controversial, it was shown to protect galactosamine-sensitized or normal mice against hepatitis and lethal shock induced by tumor necrosis factor (TNF). Rat-AGP- transgenic mice, constitutively producing several mg AGP per ml serum were tested for their response to a combined challenge with TNF and D-(+)-galactosamine. A previously characterized, single transgenic line (9.5–5) was used. In contrast to our expectations both heterozygous or homozygous transgenic mice were not protected by the endogenously overproduced AGP. However, both transgenic and non-transgenic mice were protected by pretreatment with interleukin-1, an effect which we believe is mediated by the induction of acute phase proteins like AGP. Furthermore, both types of mice were protected by exogenous bovine AGP, suggesting that the lack of protection by endogenous AGP is not because of a repressed response to AGP. Finally, we demonstrate that purified AGP from the serum of transgenic mice is as protective as the AGP from non-transgenic mice or rats. The results suggest that AGP is protective only when its concentration is rapidly induced, perhaps because the endogenous steady state synthesis of AGP, in non-transgenic as well as transgenic mice, is coupled to the production of an AGP-binding factor. This study provides an interesting example of differences in outcome to a lethal challenge between an acute administered and a chronically produced protective protein.     

Reactivity of the cerebrocortical vasculature and energy metabolism to direct cortical stimulation in haemorrhagic shock.

Direct electrical stimulation of the cerebral cortex was used to determine the changes of cortical carbohydrate and oxidative metabolism and of vascular reactivity during haemorrhagic shock. The results were as follows. 1. Electrical stimulation of the brain cortex applied in the control period led to a marked vasodilation and NAD reduction that was preceded in part of the experiments by a transient NADH oxidation. It is suggested that the increase in cortical NADH fluorescence observed during direct stimulation is due to the fact that the rate of cytoplasmic NADH production exceeded the rate of mitochondrial NADH oxidation and of the rate of H+-transport from the cytoplasm into the mitochondria. 2. The cerebrocortical vascular and NAD/NADH redox state responses induced by electrical stimulation changed in the early hypovolaemic phase of shock. At this time, electrical stimulation of the brain cortex led to NADH oxidation in the majority of the experiments or in some experiments, the stimulation did not bring about changes in the redox state of the cortex. The total loss of the reactivity to direct stimulation of the cerebrocortical vessels and of energy metabolism preceded the occurrence of cortical ischaemia during the hypovolaemic phase of shock. 3. Since after reinfusion of the shed blood, redox state and vasculature remained unresponsive to stimulation even in those experiments in which the cortical ischaemia improved, it is concluded that the carbohydrate and oxidative metabolism of the brain cortex were already irreversibly damaged in the early phase of hypovolaemic shock.     

The shoot apical meristem of oil palm (Elaeis guineensis; Arecaceae): developmental progression and dynamics

Background and Aims

Oil palm, an unbranched perennial monocotyledon, possesses a single shoot apical meristem (SAM), which is responsible for the initiation of the entire above-ground structure of the plant. To compare the palm SAM structure with those of other monocots and to study variations in its structure throughout the life of the plant, its organization was characterized from the embryonic stage to that of the reproductive plant.

Methods

SAM structure was studied by a combination of stained histological sections, light and confocal microscopy, and serial section-based three-dimensional reconstructions.

Key Results

The oil palm SAM is characterized by two developmental phases: a juvenile phase with a single tunica-corpus structure displaying a gradual increase in size; and a mature phase characterized by a stable size, a modified shape and an established histological zonation pattern. In mature plants, fluctuations in SAM shape and volume occur, mainly as a consequence of changes in the central zone, possibly in relation to leaf initiation.

Conclusions

Development of the oil palm SAM is characterized by a juvenile to mature phase transition accompanied by establishment of a zonal pattern and modified shape. SAM zonation is dynamic during the plastochron period and displays distinct features compared with other monocots.     

Cyclic nucleotides, prostaglandins and thrombocyte aggregation in rats poisoned with "murine" Yersinia pestis toxin

Y. pestis "mouse" toxin, introduced intraperitoneally into rats in a dose of LD100 [correction of LG100], produces phasic changes in the thrombin-induced aggregation of thrombocytes and the content of prostaglandins and cyclic nucleotides in them. As the result of the damaging action on the endothelium of blood vessels at the initial period of intoxication, the concentration of prostaglandin 6-keto F1 alpha in blood plasma and cAMP [correction of cAMR] in thrombocytes sharply decreases, which causes the enhancement of thrombin-induced cell aggregation. At a later period the level of prostaglandin E in the cells sharply rises. At later irreversible stages of shock, induced in the cells of Y. pestis "mouse" toxin, the content of cGMP in cells sharply increases, which leads to the development of the phase of thrombocyte hypoaggregation.     

In vivo stress preconditioning

The heat shock or stress protein response is a highly conserved defense mechanism. Activation of the stress protein response by mild hyperthermia or by pharmacological agents allows cells to withstand a subsequent metabolic insult that would otherwise be lethal, a phenomenon referred as "thermotolerance" or "preconditioning." Heat shock response is characterized by increased expression of stress proteins that provide cellular protection, e.g., via increased chaperoning activity in all organisms, from bacteria to animals and humans. Indeed, there is experimental evidence that overexpression of specific heat shock proteins or heat shock factors produce protective effects similar to those observed after stress preconditioning. The purpose of this review is first to discuss the methods used to induce in vivo thermotolerance with mild hyperthermia or pharmacological agents. Then, as an example of the organ protection provided by in vivo stress preconditioning, the second part of this paper will examine how the induction of thermotolerance modulates the lung inflammatory response associated with acute lung injury, thus providing broad organ and tissue protection against oxidative stress associated this syndrome.