Vitamin C and blood pressure--an overview

BACKGROUND: Laboratory and some epidemiological studies suggest that antioxidants, such as vitamin C, are protective for cardiovascular disease. This protective effect may be mediated through blood pressure (BP). This is the first systematic review of epidemiological studies of vitamin C and BP. METHOD: Published cross-sectional studies, prospective studies and trials in humans were identified that examined the association between vitamin C intake or plasma vitamin C levels and BP. Relevant references were located by MEDLINE search 1966-1996, EMBASE search 1980-1996, by searching personal bibliographies, books and reviews and from citations in located articles. RESULTS: Cross-sectional data were available from 18 populations. Ten of 14 reported an inverse association between plasma vitamin C and BP and three of four reported an inverse association with vitamin C intake. The two non-randomised and four randomised controlled trials were all small. Of the randomised trials one reported a significant decrease in BP, one a non-significant decrease and two were uninterpretable. CONCLUSIONS: We found a consistent cross-sectional association between higher vitamin C intake or status and lower BP, though no study controlled adequately for confounding by other dietary factors. Further cross-sectional studies are required to establish whether an independent association exists. If this is shown to be the case larger and longer term trials will be needed to confirm the association is causal. Potentially the impact on cardiovascular disease of a modest change in mean population vitamin C intake is large.     

Vitamin C status and blood pressure

STUDY OBJECTIVE: To assess the efficacy of laparoscopic low-watt bipolar electrocoagulation of the ovaries in women with polycystic ovary disease (PCOD). DESIGN: Prospective case series. SETTING: Hospital-based infertility clinic. PATIENTS: Seventy-four consecutive infertile women with PCOD resistant to conventional ovulation-induction regimens. INTERVENTIONS: Laparoscopic bipolar low-watt electrocoagulation of the ovarian surface (25 W for 5-12 sec/cyst). MEASUREMENTS AND MAIN RESULTS: Postoperative follow-up ranged from 18 months to 7 years. Menstrual rhythm returned to normal in all 74 women. All 40 women in whom infertility was solely due to anovulation eventually conceived. Overall, 62 (84%) of the 74 women conceived, 42 spontaneously after surgery and 20 after supplementation with clomiphene. These 62 women had a total of 93 pregnancies: 79 singleton live births, 4 sets of twins, and 10 miscarriages. Twenty-five women conceived twice and three conceived three times. At second-look laparoscopy or cesarean section in 20 women, fine stringlike adhesions on the ovaries were found in 2. CONCLUSION: Laparoscopic low-watt bipolar electrocoagulation of the ovaries is an effective treatment for women with PCOD who fail medical therapy.     

Increase in red blood cell triiodothyronine uptake in untreated unipolar major depressed patients compared to healthy volunteers

1. Kinetic parameters of red blood cell (RBC) L-triiodothyronine (T3) initial uptake (Vmax, maximal velocity and Km, Michaelis constant) were determined in 34 untreated inpatients suffering from unipolar depression and in 40 healthy volunteers. 2. Both Vmax and Km were significantly increased in depressed patients as compared to controls. The alterations in kinetic parameters were not associated with the severity of depression. 3. Out of the 19 depressed patients who were submitted to TRH test, 7 of them (36%) showed a blunted TRH-induced TSH response associated with a Vmax situated outside the control mean value +/- 1 S.D. 4. The authors found a significant positive correlation between Vmax of RBC L-T3 and L-tryptophan (TRP) uptakes which is in agreement with the assumption that L-T3 and L-TRP share a common carrier system at the erythrocyte level. 5. The results indicate that the uptake of L-T3 by RBC is increased in major depression. These transport perturbations might reflect alterations in the plasmatic metabolism of L-T3. Evaluation of RBC L-T3 uptake could be useful in a best biological characterization of the depressed patients with regard to their thyroid function.     

Current red blood cell transfusion practices

The appropriate use of blood transfusions remains variable among health-care institutions and patient populations. Transfusion practices are discussed in this article in relation to medical practice guidelines and utilization review. Specific transfusion practices in the settings of intensive care, orthopedic surgery, and open heart surgery are reviewed. A new, promising approach to improving transfusion outcomes is the use of transfusion algorithms. Transfusion algorithms may prove especially useful if they incorporate point-of-care testing that is both physiologic and patient-specific for transfusion decisions. Transfusion algorithms are discussed and data presented for cardiac surgical adults.     

Formation of glutathione conjugates of prostaglandin A1 in human red blood cells

When prostaglandin A1 was incubated with a Tris/saline suspension of washed human red blood cells, a substantial amount was converted to polar metabolites. These were purified by solvent extraction, XAD-2 column, and cellulose thin layer chromatography and characterized by chromatography, amino acid analysis, and mass spectrometry. The polar metabolites were a mixture of two glutathione conjugates of prostaglandin A1. The first (approximately 40%) was identical with the product of the nonenzymic reaction of glutathione with prostaglandin A1. The second (approximately 60%) was formed from the first by reduction of the 9-keto group of the prostaglandin moiety. The latter compound was also prepared synthetically by treating the glutathione conjugate of prostaglandin A1 with sodium borohydride.     

Bone-marrow imaging in pure red blood cell aplasia

Bone-marrow scintigraphy with indium chloride in 111 was performed on a patient with pure red blood cell aplasia before and after successful treatment with immunosuppressive drugs. The return of erythroid precursors to the bone marrow was accompanied by a substantial increase in the marrow uptake of 111In. The distribution of 111In in the posttreatment scan was indistinguishable from that of 52Fe. These results indicate that indium chloride in 111 is a useful agent for the delineation of erythroid cellularity within bone marrow.     

Levels of glutathione and 2,3-diphosphoglycerate in the red blood cells of Australian Aborigines

There were no significant differences in packed cell volume (PCV) and red cell 2,3-diphosphoglycerate (2,3-DPG) levels in Australian Aborigines and Caucasians. A highly significant negative correlation was found between PCV and 2,3-DPG in both Aborigines (r = 0.251; n = 231) and Caucasians (r = 0.435; n = 227). Levels of reduced glutathione (GSH) in the red blood cells of Aborigines were significantly lower (P < 0.001) compared to those of Caucasians. There was a significant negative correlation between PCV and GSH in both the groups; (Aborigines r = -0.637, n = 115; Caucasians r = 0.388, n = 111).     

Relation between zinc content in saliva and blood in healthy human adults

Measurements were made of zinc levels in saliva, whole blood and plasma as well as copper levels in plasma by atomic absorption spectrophotometry. The mean zinc concentration (in ppm) was 0.478 (n = 136) in resting mixed saliva, 0.046 (n = 36) in parotid saliva, 6.41 (n = 145) in whole blood and 0.87 (n = 145) in plasma. The whole blood zinc levels were significantly lower in females than in males (P less than 0.001). Females and blood donors (males) had a significantly (P less than 0.001) higher Cu:Zn ratio than males (non-donors). It would thus appear, first, that the local effect of salivary zinc cannot be assessed simply from the concentration of zinc in stimulated parotid saliva since about nine-tenths of the zinc in resting mixed saliva is derived from other sources and, second, that the Cu:Zn in plasma is the most eligible variable for detecting sub-clinical Zn deficiency.     

Normal variation in cutaneous blood content and red blood cell velocity in humans

This study was designed to determine normal variations in cutaneous blood content, red blood cell content and skin thickness in healthy human volunteers. The blood content (BC) of human skin and the velocity of red blood cells (RBV) has been comprehensively mapped over 30 anatomical sites in 28 volunteers between the age of 7 and 77 years using reflectance spectrophotometry (RFS) and laser Doppler (LD) techniques respectively. Total skin thickness, which may have a relationship with blood content, has been mapped at the same anatomical sites in six of the volunteers using two-dimensional array, 12 MHz ultrasound equipment. The major determinant of BC and RBV was found to be anatomical site. Regardless of age, gender or prior sun exposure, anatomical sites above the waist produced higher readings than below. BC and RBV were found to be dependent on age and gender at most sites with higher readings being observed in males and younger volunteers. The largest difference was seen in males under 55 years whose RFS readings above the waist were significantly higher than in older males or females of any age. Heavy prior sun exposure and skin thickness could not be demonstrated to impact on either RFS or LD readings independently of the effects of anatomical site, gender or age. In general, RFS and LD readings paralleled one another and correlated linearly at most anatomical sites. While RFS readings tended to decrease in the cranio-caudal direction, LD readings were relatively uniform across the body except for the head and groin where they were higher, and the abdomen where they were lower. The site-to-site variations in RFS readings observed in this study correspond well to capillary density variations noted in previous studies.     

Activities of superoxide dismutase and glutathione peroxidase in the red cells of Japanese acatalasemia blood

Trichophyton violaceum was cultured on a Sabouraud's dextrose agar slants for freeze-fracture replication. It was cryoprotected with glycerol and sucrose. The surface structure of the cell wall showed a rodlet pattern. Invagination-like craters were observed in the plasmalemma. The nuclear envelope with pores, mitochondria, and vacuoles were clearly shown. Three-dimensional views of the fine structure were presented.     

The mechanism of chlorpromazine-induced red blood cell swelling

1. Chlorpromazine (CPZ)-induced red blood cell (RBC) swelling was investigated by determination of electrolyte, mean cell volume (MCV) and water content changes in CPZ-treated cells. 2. CPZ-induced RBC swelling is dose-, hematocrit- and pH-dependent, and is associated with a net increase in RBC monovalent cation and Cl- contents. 3. The partition coefficient (Kp) for the CPZ-RBC membrane interaction is pH dependent (Kp = 2500 at pH 7.8; Kp = 840 at pH 6.8). 4. Despite the pH dependence of Kp values an equal number of CPZ molecules is required to induce a 12% increase in MCV at pH 7.8 and 6.8.     

Early post-radiation changes of red blood cell shape in rats

Scanning electron microscopy (SEM) of red blood cells in whole blood samples from rats was performed following acute gamma-irradiation of animals with 0.25 to 1 Gy. Increased incidence of echinocytosis was observed and found to be dose- and time-dependent. At a higher radiation dose (1 Gy), echinocytosis was revealed within 5 minutes after treatment and persisted up to 3 weeks. The data demonstrate the applicability of SEM for detecting minimal radiation-induced lesions of red blood cells.     

Oral endotoxin in healthy adults

A case is presented which is thought to be the first described example of rib fracture occurring as a result of airbag inflation. It would appear that the propellant cartridge came loose during deployment to form a missile, striking the patient on his chest and fracturing a rib.     

Static equilibrium configurations of a model red blood cell

The membrane of the red blood cell is modeled as a fluid shell which resists bending and changes in area. The differential equations governing the mechanical equilibrium of such a membrane are derived and axisymmetric solutions are obtained numerically.     

Rabbit red blood cell hexokinase. Purification and properties

Rabbit red blood cell hexokinase (EC 2.7.1.1.) has been purified 300,000-fold by a combination of ion exchange chromatography, affinity chromatography, and preparative polyacrylamide gel electrophoresis. The hexokinase activity has been isolated in 35% yield as a protein that is homogeneous by polyacrylamide and sodium dodecyl sulfate gel electrophoresis. The highest specific activity obtained was 145 units/mg of proteins. The native protein has a molecular weight of 110,000 by gel filtration on Ultrogel AcA 44 and 112,000 by sedimentation velocity on sucrose density gradients. Sodium dodecyl sulfate-polyacrylamide gels gave a molecular weight of 110,000 indicating that hexokinase is a monomer. The enzyme had a pI of 6.20 to 6.30 pH units by isoelectric focusing. The enzyme was specific for Mg . ATP and Mg . ITP as the nucleotide substrates. Several hexokinase with different affinities.     

贫血患者红细胞参数检测的参考价值

贫血是指全身循环血液中红细胞总量减少至正常值以下.但由于全身循环血液中红细胞总量的测定技术比较复杂,所以临床上一般指外周血中血红蛋白的浓度低于患者同年龄组、同性别和同地区的正常标准.采用MCV和RDW两项指标对贫血进行新的形态学分类,对贫血的鉴别诊断有一定的参考价值.     

Absence of cytokine receptor-dependent specificity in red blood cell differentiation in vivo

Erythropoietin (EPO) is required for red blood cell development, but whether EPO-specific signals directly instruct erythroid differentiation is unknown. We used a dominant system in which constitutively active variants of the EPO receptor were introduced into erythroid progenitors in mice. Chimeric receptors were constructed by replacing the cytoplasmic tail of constitutively active variants of the EPO receptor with tails of diverse cytokine receptors. Receptors linked to granulocyte or platelet production supported complete erythroid development in vitro and in vivo, as did the growth hormone receptor, a nonhematopoietic receptor. Therefore, EPOR-specific signals are not required for terminal differentiation of erythrocytes. Furthermore, we found that cellular context can influence cytokine receptor signaling.     

Prevalence of hepatitis B and C viruses in healthy Indonesian blood donors

Blood samples were collected from 7572 healthy volunteer blood donors from 21 of the 27 Indonesian provinces, and tested for antibodies to hepatitis C virus (anti-HCV) using the new second-generation enzyme immunosorbent assay, and also tested for hepatitis B surface antigen (HBsAg). We detected anti-HCV in 2.1% of the blood donors. No statistically significant difference was found between males and females or between locations, but there was a statistically significant increasing likelihood of anti-HCV prevalence with increasing age. HBsAg was found in 8.8% of the 3839 tested donors. There was no statistically significant difference between sexes or age groups, but there was a statistically significant higher prevalence in the islands of Sulawesi and eastern Indonesia. Only 7 individuals, from 5 locations, were both anti-HCV and HBsAg positive. Based on responses to a questionnaire, a history of surgery, blood transfusion, intravenous medication, and acupuncture were identified as risk factors for the presence of anti-HCV. No such risk factor was identified for HBsAg prevalence. The combined data suggest separate modes of transmission for the 2 viruses, and indicate the need for continued surveillance for these agents in Indonesian blood banks.