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Results for “Stage shift”

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PubMed1989

[Clinico-laboratory parallels in changes in the cerebrospinal fluid and the immune status of patients with early stages of syphilis].

A total of 135 patients with early syphilis were examined, 24 of these with primary seropositive, 31 with secondary new, 70 with secondary relapsing, and 10 with latent early condition. Abnormal shifts were revealed in the cerebrospinal fluid of 51 (37%) patients, in 28 of these Stages I-II shifts, Stages II-III shifts in 10, and Stages III-IV shifts in 13 patients. Clinically the patients with abnormal liquor developed multiple chancres, erosive papules, leukoderma, alopecia, neutrophilia; these patients had suffered from various diseases in the past. Immunologic examinations have detected manifest noncoordination of the immune system: increased counts of the T-lymphocytes and plasmacytes, reduced counts of B-lymphocytes, depressed primary immune response, disordered immunoglobulin ratio.

Adult↗

PubMed1997

Neuropsychological function in young patients with unipolar major depression.

BACKGROUND: While neuropsychological studies have consistently reported impaired cognition in elderly patients with unipolar depression, studies of cognitive function in younger patients with depression have produced equivocal results. The aim of this study was to examine the presence and nature of cognitive deficits in young patients with depression. METHODS: Neuropsychological function was assessed in 20 young patients with unipolar depression, in comparison to 20 age-, education- and IQ- matched controls. Subtests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) were employed, as this battery has proved sensitive to deficits in middle-aged and elderly patients with depression. RESULTS: The patients were not impaired for short-term memory capacity, spatial working memory, planning ability, cognitive speed, delayed matching to sample or recognition memory. Compared to controls, the patients showed impaired subsequent movement latencies on the Tower of London task, suggesting deficits in the ability to sustain motor responses in depression. The depression group were also impaired on the task of attentional set shifting, requiring more trials to criterion at the intradimensional stage of the task and being more likely to fail the task at the extradimensional shift stage than controls. Further analysis indicated that half of the depression group failed to complete all stages of the set shifting task. These patients were more likely to have required in-patient hospitalization at some time during their illness. CONCLUSIONS: These results indicate that there are specific cognitive deficits in young patients with depression and that their presence may be related to a history of hospitalization.

Adolescent↗

PubMed1982

Developmental genetics of a temperature-sensitive RNA polymerase II mutation in Drosophila melanogaster.

Purified RNA polymerase II (RNA nucleotidyl-transferase; EC 2.7.7.6) extracted from flies possessing lesions in the Ultrabithorax-like (Ubl) locus of Drosophila melanogaster has altered activity in vitro (Greenleaf et al. 1979, 1980; Coulter and Greenleaf 1982). This strongly suggests that the Ubl locus encodes a subunit of RNA polymerase II. Ethyl methanesulfonate was used to induce a temperature-sensitive mutation in this locus. Flies either homozygous or hemizygous for this new X-linked mutation (Ublts) display viability comparable to that of wild-type flies at 22 degrees C but are lethal at 29 degrees C. The temperature-sensitive period for Ublts flies is between gastrulation (6 h, 29 degrees C) and pupation (9-10 days, 22 degrees C). Zygotes shifted from 22 degrees C to 29 degrees C die at either the late embryonic or first larval instar stage while temperature shifts of second and third instar larvae result in the lethal phase occurring at the pupal stage. Most pupae shifted from 22 degrees C to 29 degrees C undergo metamorphosis and eclose as adults. Adults are viable if placed at 29 degrees C; however, all females and some males become sterile if maintained at this temperature. Somatic recombination was used to induce clones homozygous for a null allele of Ubl at different stages of development. Clones of this null allele appear to be cell lethal indicating that the Ubl+ gene product is required at all stages of development. The viability of Ublts pupae and adults at 29 degrees C may result from only a partial reduction in activity caused by the mutation at this nonpermissive temperature.

Alleles↗

PubMed1994

Development in vitro of free-living infective larvae to the parasitic stage of Strongyloides venezuelensis by temperature shift.

Free-living infective larvae Strongyloides venezuelensis were cultured in Dulbecco's modified Eagle's medium at 25 and 37 degrees C, and development to the parasitic stage was evaluated using morphological, protein and antigenicity criteria. Few larvae cultured at 25 degrees C showed development whereas, in most of the larvae cultured at 37 degrees C, there appeared characteristic changes such as a bulb-like head and droplets under the cuticle with an increase of body width of the larvae. The results obtained from two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) revealed that the protein spot patterns of the larvae cultured at 25 and 37 degrees C were differentiated by 17 specific spots. In addition, Western blot analysis combined with 2D-PAGE for reaction with serum obtained from an infected rat revealed that protein spots showing immunodominant antigen at 37 degrees C were almost the same as those of the larvae recovered from the rats rather than those of the larvae at 25 degrees C. These results strongly suggested that a temperature shift from 25 to 37 degrees C has an important role in the development of free-living infective larvae to the parasitic stage of S. venezuelensis. The culture system established in the present study was useful for biological and biochemical studies in the development from/of the free-living to the parasitic stage of Strongyloides species.

Animals↗

PubMed2001

Aldosterone and the hypertensive kidney: its emerging role as a mediator of progressive renal dysfunction: a paradigm shift.

End-stage renal disease (ESRD) comprises an enormous public health burden, with an increasing incidence and prevalence. Hypertension is a major risk factor for progressive renal disease. This escalating prevalence suggests that newer therapeutic interventions and strategies are needed to complement current antihypertensive approaches. Although much evidence demonstrates that angiotensin II mediates progressive renal disease, recent evidence also implicates aldosterone as an important pathogenetic factor in progressive renal disease. Several lines of experimental evidence demonstrate that selective blockade of aldosterone, independent of renin-angiotensin blockade, reduces proteinuria and nephrosclerosis in the spontaneously hypertensive stroke-prone rat model and reduces proteinuria and glomerulosclerosis in the subtotally nephrectomized rat model (i.e. remnant kidney). Whereas pharmacological blockade with angiotensin II receptor blockers and angiotensin-converting enzyme inhibitors reduces proteinuria and nephrosclerosis/ glomerulosclerosis, selective reinfusion of aldosterone restores these abnormalities despite continued renin-angiotensin blockade. Aldosterone may promote fibrosis by several mechanisms, including plasminogen activator inhibitor-1 expression and consequent alterations of vascular fibrinolysis, by stimulation of transforming growth factor-beta 1, and by stimulation of reactive oxygen species. Based on this theoretical construct, randomized clinical studies will be initiated to delineate the potential renal-protective effects of antihypertensive therapy utilizing aldosterone receptor blockade.

Aldosterone↗

PubMed1981

Interaction of epiblast and hypoblast in the formation of the primitive streak and the embryonic axis in chick, as revealed by hypoblast-rotation experiments.

Three types of experiments were performed to determine the interaction between the epiblast and hypoblast for primitive streak formation: (1) Hypoblasts of blastoderms from stages XIII E.G & K to 3 H & H were separated from the epiblasts and rotated by 90 degrees counterclockwise; (2) hypoblasts from stages XIII E.G & K to 3 H & H blastoderms were rotated by 180 degrees; (3) hypoblasts were exchanged between blastoderms of different developmental stages and placed at 90 degrees counterclockwise to the axis of the recipient epiblast. In all blastoderms studied only a single PS developed. After rotation of the hypoblast by 90 degrees, the direction of the PS was according to the orientation of the hypoblast at stage XIII, whereas at older stages it gradually shifted towards the axis of the epiblast. At stage 3- H & H the PS is already imprinted in the epiblast and cannot be shifted. After rotation of the hypoblast by 180 degrees the PS originated at the point near the marginal zone at which the inductive part of the hypoblast interacted with a component epiblast. Conclusions are drawn about the dynamics of the inductiveness of the hypoblast and the competence of the epiblast for the PS formation and orientation.

Animals↗

PubMed1975

Shifts in ATP synthesis during preimplantation stages of mouse embryos.

The actual and potential activities of the cyochrome system were studied in cleavage-stage mouse embroys. Activities were determined by assaying embroys for total ATP and the rates of [32-P]ATP synthesis both before and after their incubation in medium supplemented either with an energy coupling site inhibitor (antimycin, amytal or cyanide) or with the FADH-linked substrate, succinate. The data indicate that there are three major shifts in the mode of ATP production during preimplantation stages: the first, between the two-cell and late four-cell stages; the second, between the eight-celland late morula stages; and the third, between the late morula and late blastocyst stages. These data are discussed in relation to studies on the energy metabolism of cleavage and blastocyst stage mouse embryos.

Adenosine Triphosphate↗

PubMed2000

Response shift in quality of life measurement in early-stage breast cancer patients undergoing radiotherapy.

In medicine, response shift refers to a change--as a result of an event such as a therapy--in the meaning of one's self-evaluation of quality of life. Due to response shift, estimates of side effects of radiotherapy may be attenuated if patients adapt to treatment toxicities. The purpose of our study was to assess to what extent two components of response shift, scale recalibration and changes in values, occur in early-stage breast cancer patients undergoing radiotherapy and to examine what the implications would be for treatment evaluation. In the week before start of post-operative radiotherapy, 46 patients filled out a questionnaire consisting of quality of life items of the SF-36 and the Rotterdam symptom checklist (RSCL) (pretest). During radiotherapy, patients were asked to fill out the questionnaire twice: a posttest (quality of life at that moment) and a thentest (quality of life before treatment, retrospectively), supposedly using the same internal standard. Changes in values were studied by asking the patients on the two occasions to rate the importance of seven attributes representing various domains of quality of life. Patients were also asked whether their quality of life with respect to the measured aspects had changed since the pretest (subjective transition scores). Significant scale recalibration effects were observed in the areas of fatigue and overall quality of life. When the groups were divided according to their subjective transition scores, significant scale recalibration effects were found in case of worsened quality of life for fatigue and overall quality of life, and in case of improved quality of life for fatigue and psychological well-being. The mean importance ratings remained fairly stable over time, except for 'skin reactions', which obtained less importance at the end of radiotherapy than before. In conclusion, effects of scale recalibration were observed that would have significantly affected quality of life evaluations, in that the impact of radiotherapy on fatigue and overall quality of life would have been underestimated. Changes in internal values were observed only for 'skin reactions'.

Adult↗

PubMed2004

Transcriptome of axenic liver stages of Plasmodium yoelii.

Plasmodium liver stages or early exo-eythrocytic forms (EEFs) contain antigens that are essential for achieving sterile, protective immunity against malaria. Yet, attempts at identifying these antigens have been hampered by the challenge of obtaining large numbers of purified EEFs, uncontaminated with hepatocyte material. Using a recently described system for producing axenically cultured EEFs from Plasmodium yoelii, we have constructed a cDNA library and generated 1453 expressed sequence tags (ESTs) resulting in 652 unique transcripts. Analysis of the library provides insight into processes required for the initiation and development of Plasmodium liver stages, such as protein degradation, cell cycle progression and nutrient transport. Analysis of the gene expression profile of liver stages, as revealed by this library, suggests that liver stages represent a shift from "sporozoite-like" to "blood-stage-like". This is the first study of the transcriptional repertoire of Plasmodium liver stages.

Animals↗

PubMed2005

[Changes in sleep architecture by resumption of CPAP in patients with sleep apnea syndrome].

It is known that application of continuous positive airway pressure (CPAP) improves sleep architecture in patients with sleep apnea syndrome (SAS). In contrast, there have been only a few studies which deal with deterioration of sleep architecture by discontinuation of CPAP. In the present study we analyzed changes of sleep architecture by temporary removal of CPAP. The subjects were 41 patients who underwent polysomnography (PSG) for diagnosis of SAS. The patients chose either a 1-night study in which only PSG was done, or a 2-night study in which, after treatment with CPAP for one month, PSGs with and without CPAP at night were done. The mean ages, heights, and weights between the 1-night group and the 2-night group were not statistically different The mean AHI of the 1-night group (38.9 +/- 5.0/hr; mean +/- SE) and that of the 2-night group (45.7 +/- 5.4/hr) were not significantly different. The mean AHI profoundly decreased (4.4 +/- 0.9) by CPAP therapy on the second night. Percents of each sleep stage in the 1-night group were as follows; stage 1, 31.8%; stage 2, 50.0%; stage (3 + 4), 2.8%: REM, 15.7%. In the 2-night group, stage 1 was 43.6%, significantly higher than that in the 1-night group, while stage 2 was 39.9%, which was significantly smaller. There were no significant difference in stage (3 + 4) and REM. When CPAP was again applied to the 2-night patients, stage 1 significantly decreased to 15.5%, while stage 2 (55.6%), stage (3 + 4) 6.7%, and REM (22.3%) increased significantly. Therefore, cessation of CPAP shifts the sleep stage from stage 2 to stage 1. Since stages 1 and 2 occupy approximately 80% of total sleep duration, the shift may have some physiological significance. Resumation of CPAP may have improved quality of life and day-time sleepiness by decreasing stage 1 sleep and increasing stages of deeper sleep and REM.

Continuous Positive Airway Pressure↗

PubMed1981

Cortical power spectrum analysis of hypnotic pain control in surgery.

Cortical power spectrum (CPS) of brain potentials was recorded from the scalp between prefrontal and parietal regions in both right hemisphere (RH) and left hemisphere (LH). A pattern of laterality shift in CPS occurred at different stages during an extensive oral surgery, performed under hypnosis, in a young female patient. Video and audio recordings as well as psychophysiological recordings were obtained through the following 6 stages: Baseline, Hypnosis, Surgery (1 hr, no cortical recording), Immediate Postsurgery Procedure, Hypnotic Re-experience, Hypnotic Rest, and Posthypnotic Baseline. Indications of anxiety and pain scores were reported in writing by the patient through verbal command by the hypnotist. In each stage, 10 min of CPS (10 spectrum/stage, 8 epochs/spectrum, 6 seconds/epoch) were analyzed by a PDP-11 computer. The results of CPS analysis demonstrated significant large total power reduction at different stages. There was significant correlation between both hemispheres at baseline, but dissociation of hemispheric power output occurred during hypnosis stages. LH was more dominant than RH during baseline and presurgery hypnosis, but both were leveled-off immediately following the surgery procedure. However, RH became more dominant during all postsurgery hypnosis stages. Interestingly, this pattern shifted back to the original relationship during the posthypnotic baseline stage. Specific changes of spectral power in theta and alpha of EEG activities in both hemispheres also occurred in conjunction with hypnosis.

Adult↗

PubMed2005

Prognostic value of the 2002 TNM classification for breast carcinoma with regard to the number of metastatic axillary lymph nodes.

BACKGROUND: The American Joint Committee on Cancer (AJCC) TNM classification for breast carcinoma had not been changed for 15 years, since the publication of the third edition in 1987. However, in the sixth edition, published in 2002, significant modifications were made with regard to the number of metastatic axillary lymph nodes. The authors investigated whether the sixth edition of the TNM classification provided more reliable prognostic information compared with the third edition. METHODS: The records of 1230 patients who underwent surgery for invasive breast carcinoma between 1993 and 1999 were reviewed. Each patient was assigned to axillary lymph node and disease stage groups according to the 1987 and 2002 AJCC TNM classifications. Disease-free survival (DFS) curves were calculated and plotted using the Kaplan-Meier method and the two-sided log-rank test was used to compare the survival curves of the patient groups. RESULTS: Of the 1067 patients who were classified as having Stages II and III disease according to the 1987 classification, 411 (38.5%) were shifted to higher disease stages using the 2002 classification. Among the 1987 Stage IIA, Stage IIB, and Stage IIIA patients, the DFS rates of the patients who were shifted to higher stages of disease were significantly worse than those of the patients for whom the stage of disease was not changed. Among those patients classified as having T4anyNM0 (Stage IIIB) disease according to the 1987 classification, there was no survival difference noted between those patients with T4N0,1,2M0 disease (who formed the Stage IIIB group) and those with T4N3M0 disease (who formed the Stage IIIC group) according to the new staging system. Of the 221 patients who formed the new Stage IIIC group, 12.2% were classified as having Stage IIA disease, 42.1% as having Stage IIB disease, 38.9% as having Stage IIIA disease, and 6.8% as having Stage IIIB disease according to the 1987 classification. The survival rates of these Stage IIA, Stage IIB, and Stage IIIA patients were not found to be significantly different; however, the survival of patients in the Stage IIIB group was found to be significantly worse than the survival of the patients in the other disease stage groupings, and the patients in the Stage IIIC group were not a prognostically homogeneous group. On the basis of these results, the authors placed patients with T4anyNM0 disease in the same group (Stage IIIB). When the 2002 classification was rearranged in this manner, patients with Stage IIIC disease formed a homogeneous group; the 5-year DFS rate of patients with Stage IIIB disease was found to be significantly worse than that for patients with Stage IIIC disease (P = 0.0011). CONCLUSIONS: In the 2002 TNM classification for breast carcinoma, patients with T4anyNM0 disease should form a distinct stage grouping and this stage grouping (Stage IIIC) should be placed before Stage IV, and Stage IIIB disease groupings should include patients with T1,2,3N3M0 disease. In this way, the authors hope that the 2002 AJCC TNM classification, which provides more reliable prognostic information than the 1987 classification, will become more refined.

Breast Neoplasms↗

PubMedDate not supplied

[Spatial synchronization of cortical electrical activity at different stages of visual set in preschool children].

Changes in the alpha-rhythm synchronization were revealed at different stages of cognitive visual set in 5- to 7-year-old children. We found a clear-cut correlation of these changes with set plasticity. In children with a plastic set, the EEG synchronization between the frontal and other brain regions substantially increased in the period of set-shifting (the actualization stage). At the set extinction stage, after set-shifting has already taken place, the EEG-synchronization becomes minimal. On the contrary, in children who formed a rigid set, EEG coherence considerably increases at the set extinction stage. This finding suggests that the rigid set still affects the cognitive activity even after (judging from oral reports) the set shift has been completed. The age-related differences in cognitive set formation clearly correlate with the time course of the EEG synchronization between the frontal and other brain regions. We think that the ability to form a plastic visual set depends on the frontal cortex maturation, which occurs at the age of 6-7 years, and its age-related effect on the brain cognitive functions.

Age Factors↗

PubMed2004

[Short-term and long-term influences of nasal continuous positive airway pressure to sleep architecture of obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To observe the short-term and long-term influences of nasal continuous positive airway pressure (nCPAP) to sleep architecture of obstructive sleep apnea hypopnea syndrome (OSAHS). METHODS: Thirty cases who were diagnosed as OSAHS patients by polysomnography (PSG) were enrolled in the study. They received the nCPAP treatment in hospital at first night and then at home. Seventeen healthy adults were enrolled as control group and experienced PSG monitoring and recording. The sleep architectures of control group and OSAHS group (before nCPAP, first night on the nCPAP and 6 months after continuous nCPAP treatment) were analysed. RESULTS: The sleep shift number, first stage sleep, second stage sleep, stage of slow wave sleep and stage of rapid eye movement (REM) sleep were 34.41 +/- 10.16, (5.95 +/- 3.89)%, (48.13 +/- 7.68)%, (18.30 +/- 4.71)%, and (26.83 +/- 6.65)%, respectively, in control group. These parameters in OSAHS group before nCPAP were 207.30 +/- 149.80, (21.42 +/- 10.17)%, (55.24 +/- 13.28)%, (15.38 +/- 19.57)%, and (10.15 +/- 7.82)%, respectively. At the first night of nCPAP treatment they were 55.77 +/- 25.04, (10.92 +/- 9.62)%, (50.19 +/- 13.34)%, (17.53 +/- 10.06)%, and (21.17 +/- 7.66)%, respectively. There were statistically significant differences between the PSG parameters before and after nCPAP treatment in OSAHS group (P < 0.05). After 6 months of nCPAP treatment, the stage of REM sleep was significantly shorter (P < 0.05), but the other parameters had no significant changes compared with those at the first night on nCPAP (P > 0.05). CONCLUSION: The sleep shift number and first stage sleep in OSAHS group were significantly increased, but the stage of REM sleep was significantly decreased than those in control group. The sleep architecture of OSAHS was significantly improved when the nCPAP treatment was given continuously.

Aged↗

PubMed2005

CT screening for lung cancer: five-year prospective experience.

PURPOSE: To report results of a 5-year prospective low-dose helical chest computed tomographic (CT) study of a cohort at high risk for lung cancer. MATERIALS AND METHODS: After informed written consent was obtained, 1520 individuals were enrolled. Protocol was approved by institutional review board and National Cancer Institute and was compliant with Health Insurance Portability and Accountability Act, or HIPAA. Participants were aged 50 years and older and had smoked for more than 20 pack-years. Participants underwent five annual (one initial and four subsequent) CT examinations. A significant downward shift was evaluated in non-small cell lung cancers detected initially from advanced stage down to stage I by using a one-sided binomial test of proportions. Poisson regression and Fisher exact tests were used for comparisons with Mayo Lung Project. RESULTS: In 788 (52%) men and 732 (48%) women, 61% (927 of 1520) were current smokers, and 39% were former smokers. After five annual CT examinations, 3356 uncalcified lung nodules were identified in 1118 (74%) participants. Sixty-eight lung cancers were diagnosed (31 initial, 34 subsequent, three interval cancers) in 66 participants. Twenty-eight subsequent cases of non-small cell cancers were detected, of which 17 (61%; 95% confidence interval: 41%, 79%) were stage I tumors. Diameter of cancers detected subsequently was 5-50 mm (mean, 14.4 mm; median, 10.0 mm). Analysis for a more than 50% shift in proportion of stage I non-small cell cancer detection did not show statistical significance. Forty-eight participants died of various causes since enrollment. Lung cancer mortality rate for incidence portion of trial was 1.6 per 1000 person-years. There was no significant difference in lung cancer mortality rates of cancers detected in subsequent examinations between this trial and Mayo Lung Project after separation of participants into subsets (2.8 vs 2.0 per 1000 person-years, P = .43). CONCLUSION: CT allows detection of early-stage lung cancers. Benign nodule detection rate is high. Results suggest no stage shift.

Aged↗

PubMed1986

[Study of local shiftings of the brain stem in increased intracranial pressure by a supratentorial balloon].

The study of the mechanism of pressure transmission is important for the treatment of rapid deterioration of a patient's condition with increased intracranial pressure (ICP) from a space taking lesion in neurosurgical practice. The aim of this experiment is to clarify the mechanism of pressure transmission during supratentorial balloon inflation, by continuously monitoring local shiftings of the brain using strain gauge sensors. Mongrel dogs and macaca fuscatas were fixed in stereotaxic head frames with light anesthesia. Brain shiftings were evaluated by sensors discriminating two dimensional directions, sagittal and coronal planes, at the cerebrum. Brain stem shift was measured as displacement from the midline at the midbrain and ventro-dorsal shifting in the pons. ICP was raised by inflation of a supratentorial balloon located in the frontal lobe in one group or the temporal lobe in other group. As parameters detecting the changes in the functions of the brain stem, systemic blood pressure (SAP), respiration and pupil size were simultaneously monitored. Shifting of the brain stem occurred in four staged in both groups. During a minimum increment of ICP shifts to the antiballoon side were observed at the occipital lobe and the midbrain. The pons showed no shift in stage I. During the further inflation of the balloon stage II, the pons started to shift to the ventral side. In this stage the temporal lobe, in addition to the occipital lobe, shifted to the antiballoon side. There was a tendency for stage II to last longer for the frontal balloon than for the temporal balloon.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Apoptosis mediates and thymidine prevents erythroblast destruction in folate deficiency anemia.

Deficiency of the vitamin folic acid causes pancytopenia by decreasing the production of new blood cells. Although impaired DNA synthesis and destruction of hematopoietic cells have been implicated, the mechanism by which folate deficiency decreases blood cell production is uncertain. An in vitro model of folate-deficient erythropoiesis was developed by using proerythroblasts isolated from folate-deficient mice that were infected with Friend leukemia virus. Proerythroblasts from folate-deficient mice had one-tenth the total folate as did proerythroblasts from control mice. The folate-deficient proerythroblasts underwent apoptosis, a form of programmed cell death, after 20-32 h in culture in folate-deficient medium. At the time of apoptosis the cells had differentiated into the later erythroblast stages and some had begun hemoglobin synthesis. Addition of either folic acid or thymidine, but not deoxycytidine or inosine, to the folate-deficient medium prevented the apoptosis and permitted proliferation and differentiation of the proerythroblasts into reticulocytes. The prevention of apoptosis by thymidine indicates (i) that decreased thymidylate synthesis plays a role in erythroblast apoptosis and the anemia of folate deficiency and (ii) that DNA cleavage is likely to be a primary event in the apoptosis of folate-deficient erythroblasts. Apoptosis of erythroblasts in the late stages of differentiation leads to decreased erythrocyte production and to anemia. The increased erythropoietin produced in response to the anemia increases the number of erythroid progenitor cells in the differentiation stages preceding those in which the cells undergo apoptosis. This population shift to earlier stage erythroblasts and proerythroblasts is characteristic of bone marrows of individuals with folate deficiency anemia.

Animals↗

PubMed2005

[Changes in sensitivity of vascular smooth muscle to calcium and its role in the biphasic change in vascular reactivity following hemorrhagic shock in rats].

OBJECTIVE: To observe the change in sensitivity of vascular smooth muscle to calcium and its role in biphasic vascular reactivity following hemorrhagic shock (HS) in rats. METHODS: The superior mesenteric artery (SMA) obtained from rats with HS was used to assay the vascular reactivity and sensitivity to calcium by observing the contraction initiated by norepinephrine (NE) and Ca(2+) under depolarizing conditions (120 mmol/L K(+)) with isolated organ perfusion system. At different time points after shock, the relationship between vascular reactivity and sensitivity to calcium was analyzed. Meanwhile the effects of the angiotensin II (Ang II) and insulin, the calcium sensitivity regulating agents, on vascular reactivity were also observed. RESULTS: As compared with the control group, the cumulative dose-response curves of SMA to NE and Ca(2+) at early shock stages, i.e. immediately and 30 minutes after shock, shifted to the left, the maximal contractions (Emax) of NE and Ca(2+) were increased significantly (P<0.05 or P<0.01). But the cumulative dose-response curves of SMA to NE and Ca(2+) at late shock stage shifted to the right, and Emax of NE and Ca(2+) were significantly decreased (P<0.05 or P<0.01). Ang II increased the contractile response of SMA to NE and Ca(2+) when shock persisted for 2 hours, rendering the cumulative dose-response curves of NE and Ca(2+) shifted to the left (P<0.05 or P<0.01). But insulin decreased the contractile response of SMA to NE and Ca(2+) at early stage of shock, rendering the cumulative dose-response curves of NE and Ca(2+) shifted to the right (P<0.05 or P<0.01). CONCLUSION: Sensitivity of vascular smooth muscle to calcium following hemorrhagic displays a biphasic change. It plays important roles in biphasic vascular reactivity.

Animals↗