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PubMed1993

Role of vagal nerves and atrial natriuretic hormone in vasopressin release and a diuresis under hypertonic volume expansion.

To assess whether increases in circulating atrial natriuretic hormone (ANH) in response to the plasma volume expansion, besides the volume receptor-mediated mechanisms, attenuate the arginine vasopressin (AVP) response to increased plasma osmolality and whether changes in plasma AVP and ANH affect renal solute excretion under hypertonic plasma volume expansion, hypertonic saline (0.95 mol/l saline) alone, hypertonic saline with 6% dextran (6D-HS) and hypertonic saline with 9% dextran (9D-HS) were administered into anesthetized dogs. In the control study, 0.15 mol/l NaCl alone was administered. Plasma AVP and ANH and cardiovascular and renal functions were determined. Hypertonic saline and 9D-HS also were administered into the vagotomized and sham operated dogs, and the same parameters were determined. Mean blood pressure and heart rate never changed in all the groups, but central venous pressure and plasma volume increased markedly in 6D-HS and 9D-HS groups. In the control and hypertonic saline groups, central venous pressure increased slightly but plasma volume never changed. Plasma AVP increased in the order of hypertonic saline, 6D-HS and 9D-HS, but plasma ANH increased in reverse order. Vagotomy restored the AVP response to 9D-HS to 75% of its response to hypertonic saline, with a marked rise in plasma ANH. Urine sodium and potassium excretion and urine flow increased in hypertonic saline, 6D-HS and 9D-HS groups, but these increases were comparable among the groups. In the control group, these parameters never changed. These results suggest that the volume receptor-mediated vagal neural and ANH responses to the plasma volume expansion may have an effect on the suppression of the AVP response to osmotic stimuli, and increased plasma ANH release never potentiated the natriuresis under the hypertonic plasma volume expansion.

Animals↗
PubMed1983

Cardiac function and peripheral circulatory adjustments in patients with acute myocardial infarction. Observations during the early stage of AMI.

Since little is known concerning the effect of different types of cardiac dysfunction on the peripheral circulation in acute myocardial infarction, cardiac and peripheral circulatory hemodynamics were measured simultaneously and sequentially in the Coronary Care Unit in 40 patients with acute myocardial infarction (AMI) using a Swan-Ganz catheter and venous occlusion plethysmography. Patients were classified by clinical assessment (Killip) and into four hemodynamic subsets (HS) according to pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) measures obtained by invasive central hemodynamic monitoring (Forrester): uncomplicated AMI, HS-I (PCWP less than or equal to 18 mmHg, CI greater than 2.2 L/min/m2) 15; pulmonary congestion, HS-II (PCWP greater than 18 mmHg, CI greater than 2.2 L/min/m2) 15; peripheral hypoperfusion, HS-III (PCWP less than or equal to 18 mmHg, CI less than or equal to 2.2 L/min/m2) 4; cardiogenic shock, HS-IV (PCWP greater than 18 mmHg, CI less than or equal to 2.2 L/min/m2) 6. Measurements taken within 48 hours after the onset of AMI showed significantly lower calf blood flow (p less than 0.05) and calf venous capacitance (p less than 0.01) and higher calf vascular resistance (p less than 0.05) in all AMI classifications compared to 10 normal subjects. In uncomplicated AMI group (Killip I and HS-I) calf blood flow and venous capacitance were significantly reduced while calf vascular resistance remained unchanged from normal. In AMI complicated by pulmonary congestion (Killip II and HS-II), in addition to reduced calf venous capacitance, calf blood flow was further significantly reduced (p less than 0.05) due, in part, to a rise in calf vascular resistance (p less than 0.05). In AMI complicated by severe heart failure and shock (Killip III, VI and HS-IV), mean changes in the periphery were not statistically different from those seen in patients with pulmonary congestion alone. In patients with AMI complicated by poor peripheral perfusion (HS-III), the peripheral changes did not show significant differences from those seen in uncomplicated AMI (HS-I). Significant correlations were found between calf blood flow and PCWP (r = -0.37, p less than 0.05) and CVP (r = -0.31, p less than 0.05); calf vascular resistance and PCWP (r = +0.36, p less than 0.05) and systemic vascular resistance (r = +0.43, p less than 0.01). Sequential daily peripheral hemodynamic changes in 14 H-I patients not requiring specific therapy showed that calf blood flow took 5 days, calf vascular resistance 3 days and calf venous capacitance 7 days to return to within normal levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2004

Healthy Steps: a case study of innovation in pediatric practice.

Healthy Steps (HS) represents a significant innovation in the way pediatric primary care can be delivered. Based on the standards and principles of Bright Futures and the American Academy of Pediatrics Health Supervision Guidelines, HS enhances and expands traditional pediatric care by including a child development specialist (Healthy Steps specialist) as part of the pediatric practice team. Services offered by this person, typically a nurse, early childhood educator, or social worker, include more time to spend discussing preventive issues during well-child visits, home visits, a telephone information line exclusively addressing developmental and behavioral concerns, new written materials, and more seamless linkages to community resources and parent support groups. The original HS cohort consisted of 15 pediatric practices in a variety of settings (private practices, health centers, pediatric training programs). Evaluated for the effects of HS on their family were 3737 intervention and comparison families. HS families received significantly more preventive and developmental services, compared to families in the control group. HS families were also less likely to be dissatisfied with their pediatric primary care. Additionally, HS had a positive impact on parenting in many areas including adherence to health visits, nutritional practices, developmental stimulation, appropriate disciplinary techniques, and correct sleeping position. Other outcome measures (such as initiation or duration of breastfeeding, child development knowledge, sense of competence, and reports of child language development at 2 years of age) did not differ between intervention and comparison group. Compared to other early childhood intervention efforts, HS offers a comparable positive impact on parenting at a relatively inexpensive cost: an estimated 400 dollars per family per year (compared to 4500 dollars from Early Head Start). Approximately 3 years after the evaluation of HS ended, 10 of the original 24 sites are still in operation, and an additional 24 sites have started up. Although funding and reimbursement remain an important barrier, continued growth of HS suggests an abiding interest in this approach to expand and enhance preventive and developmental care in pediatric primary care.

Child↗
PubMed1994

Effects of an atrial natriuretic peptide receptor antagonist on glomerular hyperfiltration in diabetic rats.

Previous studies from this laboratory implicated atrial natriuretic peptide (ANP) as a possible mediator of glomerular hyperfiltration in diabetic rats. In this study, the potential of HS-142-1 (HS), a novel polysaccharide compound with ANP receptor antagonist properties, to ameliorate glomerular hyperfiltration in diabetic rats was assessed. Initially, it was confirmed that a bolus iv injection of HS blocked both diuretic and natriuretic responses to exogenous ANP in normal Munich-Wistar rats. The acute effects of HS in moderately hyperglycemic diabetic rats with glomerular hyperfiltration and hyperperfusion were then determined. In diabetic rats, HS (20 mg/kg bolus iv) lowered GFR by approximately 46% from hyperfiltering (1.86 +/- 0.06 mL/min) to normal (1.13 +/- 0.13 mL/min) levels, whereas GFR in vehicle-treated diabetic rats remained unchanged (1.92 +/- 0.08 mL/min to 1.77 +/- 0.09 mL/min). In nondiabetic euvolemic rats, GFR was reduced by 20% after HS, whereas GFR in vehicle-treated controls was unchanged. In contrast, HS had no effect on GFR in hydropenic rats. Effective RPF was not significantly reduced in either diabetic or normal euvolemic rats in response to HS; consequently, significant reductions in filtration fraction were observed in both groups. Urine flow and sodium excretion rates were significantly reduced after HS in both diabetic and nondiabetic groups but not in hydropenic or vehicle-treated groups. These data show that HS ameliorates glomerular hyperfiltration in diabetic rats, further supporting the hypothesis that intrarenal actions of natriuretic peptides contribute significantly to glomerular hyperfiltration in experimental diabetes mellitus.

Animals↗
PubMed1993

Comparison of morning or bedtime insulin with and without glyburide in secondary sulfonylurea failure.

OBJECTIVES: New treatment options are needed for glycemic control in NIDDM. We evaluated the effects of bedtime or morning insulin treatment, combined with daytime glyburide or given alone. RESEARCH DESIGN AND METHODS: Twenty-nine male patients with NIDDM, mean age 63 +/- 1.7 yr, body weight 124 +/- 2.98% of DBW, received a maximum glyburide dose (20 mg/day) for a minimum of 6 wk, to confirm sulfonylurea failure. Human lente insulin was added for 12 wk either AM (n = 14) or HS (n = 15) and adjusted to obtain fasting euglycemia (FPG; combination treatment phase). Glyburide was then stopped, and insulin was continued for 6 wk, aiming for normal FPG (insulin phase). RESULTS: After combination treatment phase, FPG decreased (P < 0.02) from 12.43 +/- 0.68 to 5.73 +/- 0.65 mM (AM) and from 12.68 +/- 0.76 to 5.51 +/- 0.48 mM (HS) (AM vs. HS, NS). Postbreakfast, presupper, and 0200 AM plasma glucose levels fell equally (P < 0.02) except for 1-h postprandial (AM 12.46 +/- 0.51 mM, HS 10.88 +/- 0.62 mM, AM vs. HS, P < 0.1). Mean HBA1c fell similarly in both AM and HS groups. At 2 wk of the insulin phase, FPG was higher in AM than HS, 9.8 +/- 0.76 vs. 7.56 +/- 0.7 mM (P < 0.1). At the end of insulin phase, plasma glucose levels were similar to the end of combination treatment phase, but the insulin dose had to be raised in AM by 39% (P < 0.02) and HS by 30% (P < 0.05). After the combination treatment phase, fasting C-peptide was significantly suppressed in HS group only, from 1.22 +/- 0.12 to 0.82 +/- 0.09 nM (P < 0.02). At the end of insulin phase, fasting C-peptide was further suppressed in both groups, but 2-h postprandial C-peptide levels decreased significantly in AM group only, from 1.85 +/- 0.23 to 1.42 +/- 0.13 nM (P < 0.02). Triglycerides and total and HDL cholesterol did not change significantly after either combination treatment phase or insulin phase. Mean weight gain was 6.5 lb during combination treatment phase (NS from baseline), without further change during insulin phase. Hypoglycemic reactions, all mild, were recorded at a rate of 1.35/patient in the AM group and 0.4/patient in the HS group (P < 0.025). CONCLUSIONS: Normal fasting glycemia and near-normal postprandial glucose profile could be obtained with combination therapy in NIDDM. Results were similar if insulin, alone or in combination with glyburide, was given before breakfast or at bedtime, but hypoglycemic reactions were more common with conventional morning insulin injections.

Adult↗
PubMed1993

Lipid peroxidation-cytochrome P450 interactions. Use of linoleic acid hydroperoxide in the characterization of the spin-state of membrane-bound P450.

1. A procedure (linolenic acid hydroperoxide (LAHP) deletion method) is described in which LAHP is added to the reference cuvette of a pair of spectrally balanced cuvettes containing hepatic microsomes to produce a composite high spin (HS)-low spin (LS)-spectrum of P450. 2. The LAHP deletion method was used to determine the spin state of P450 in rat hepatic microsomes with and without the addition of type I compounds. 3. Advantage was taken of the temperature dependency of the spin state of P450 to determine the overall enthalpic and entropic changes for the spin equilibrium to generate computer-derived spectra of HS and LS forms of P450, and to construct a nomogram that allows direct estimation of the percentage of HS and LS spin forms of P450 in intact microsomes at temperatures compatible with biochemical functions. 4. The h.p.l.c. deletion method was used to demonstrate that HS-P450 comprised 57% of the P450 in hepatic microsomes; addition of type I substrates to these microsomes raised the level of HS-P450 to 97%. 5. The percentage of HS-P450 generated by the addition of type I compounds to microsomes declined with increasing deletions of P450 until at the extrapolated 100% level of deletion there was no HS-P450 above that of the original 57% observed in the absence of added compounds. This can be explained if LAHP destroys part of the LS-P450 while altering the remaining LS-P450 such that it retains its LS spectral characteristics but loses its capacity to form HS P450 when type I substrates are added. 6. These studies support the concept that about 50% of hepatic microsomal P450 is functionally in the HS state due to binding with high affinity endogenous substrates or other membrane components; the remaining P450 is LS-P450 that can bind to exogenous substrates to form HS-P450. 7. Applications of the LAHP deletion method for assessment of catalytic properties of membrane-bound P450 at ambient temperatures are discussed.

Animals↗
PubMedDate not supplied

Comparison of transvaginal ultrasonography with hysterosonography as a screening method in patients with abnormal uterine bleeding.

OBJECTIVE: To assess the utility of hysterosonography (HS) as a screening method in patients with abnormal uterine bleeding. MATERIALS AND METHODS: We retrospectively reviewed transvaginal ultrasonography (TVS) and HS for 105 patients whose diagnosis was confirmed pathologically. All 105 patients were initially evaluated on the same day with both TVS and HS. On TVS and HS examination, endometrial cavitary lesions were classified as diffuse hyperplasia, endometrial polyp, endometrial cancer, uterine synechia and submucosal leiomyoma. Hysteroscopy with biopsy (n=35), curettage (n=60) or hysterectomy (n=10) was performed, and the results of TVS and HS examination were correlated with the pathological findings. RESULTS: The sensitivity and specificity were 79.0% and 45.8% for TVS, and 95.1% and 83.3% for HS, respectively. The positive and negative predictive values were 83.0% and 39.3% for TVS, and 95.1% and 83.3% for HS, respectively. Twenty-seven showed a discrepancy between the TVS and HS, and eight cases showed a discrepancy between HS and the pathologic diagnosis. CONCLUSION: TVS is a sensitive method to evaluate the endometrial cavitary lesions, but it often does not provide the physician with sufficient diagnostic information. With its higher sensitivities, specificities and positive and negative predictive values, HS can be better used than TVS in evaluating those patients with abnormal uterine bleeding.

Adult↗
PubMed1999

Is hydroxylamine-induced cytotoxicity a valid marker for hypersensitivity reactions to sulfamethoxazole in human immunodeficiency virus-infected individuals?

Hypersensitivity (HS) reactions to sulfonamides and sulfones continue to limit their use in human immunodeficiency virus (HIV)-infected individuals. In vitro cytotoxicity of hydroxylamine metabolites toward peripheral blood mononuclear cells (PBMCs) has been proposed as a marker for these HS reactions. To test the validity of this in vitro system, we determined the selective susceptibility of PBMCs from HIV-infected patients to the cytotoxic effects of hydroxylamine metabolites of sulfamethoxazole (SMX) and dapsone (DDS). Concentration-cytotoxic response data were collected using PBMCs from 12 sulfa-HS (10 SMX-HS and 2 SMX/DDS-HS) and 10 sulfa-tolerant HIV-infected individuals. Although sulfamethoxazole hydroxylamine (SMX-NOH) and dapsone hydroxylamine (DDS-NOH) both caused concentration-dependent increases in cell death, DDS-NOH was significantly more potent in each subject (P <.0001). A comparison of a variety of mean data for sulfa-HS and -tolerant patient populations failed to demonstrate the increased susceptibility of PBMCs from HS patients, noted by others, to either SMX-NOH or DDS-NOH. Moreover, any trend toward an increased susceptibility of PBMCs from HS patients was eliminated when adjusted for control cell death. PBMCs from sulfa-HS patients showed significantly greater susceptibility to the stress of short term in vitro incubation (P <. 02). Mean (S.D.) vehicle control cell death values were 24.1% (7.6%) for HS patients and 17.1% (4.4%) for tolerant patients. No significant correlation was observed between hydroxylamine-induced or control cell death and any of the recorded clinical parameters. Although several potential reasons are proposed to explain the disparity with past investigations, the data suggest that in vitro cytotoxicity is not a valid marker for HS reactions in HIV-infected individuals using currently accepted experimental procedures.

Adult↗
PubMed2000

Natural history of hereditary spherocytosis during the first year of life.

Although hereditary spherocytosis (HS) is a common disorder of the red cell membrane, its clinical and biologic expression at birth and in early infancy has received little attention. In order to obtain insights into the natural history of HS during infancy, we studied 46 neonates, 39 from families in which 1 of the parents had previously been given a diagnosis of HS and 7 presenting with nonimmune hemolytic anemia and no family history of HS. Of these 46 neonates, 23 were subsequently confirmed to have HS and 23 were found to be healthy. The hematologic and biologic analyses carried out in this cohort of 46 newborns enabled us to develop guidelines for early diagnosis of HS. A careful clinical follow-up of 34 HS patients during the first year of life allowed us to define several important clinical features of HS during this period. Hemoglobin values are usually normal at birth but decrease sharply during the subsequent 20 days, which leads, in many cases, to a transient and severe anemia. The anemia is severe enough to warrant blood transfusions in a large number of infants with HS (26 of 34 in our series). The aggravation of anemia appears to be related to the inability of these infants to mount an appropriate erythropoietic response to anemia and to the development of splenic filtering function. These findings indicate that careful monitoring of infants with HS during the first 6 months of life is important for appropriate clinical management. (Blood. 2000;95:393-397)

Blood Transfusion↗
PubMed2000

Hypertonic saline infusion: can it regulate human neutrophil function?

The down-regulation of neutrophil adhesion molecule expression after hemorrhagic shock may reduce neutrophil-mediated organ injury. Hypertonic saline (HS) blocks neutrophil activation, and HS infusion in animals reduces organ injury. In this study, we investigated whether HS infusion in healthy human volunteers can affect neutrophil function. Healthy human volunteers were administered either 4 mL/kg of a 7.5% HS (n = 6) or normal saline (NS, 0.9%; n = 5) over 15 min. Mean arterial pressure (MAP) and plasma sodium levels were measured. Blood samples were obtained before and 1 h after fluid administration. Cells were stimulated with fMLP or left untreated. Neutrophil phagocytosis and expression of CD11b and L-selectin was determined with flow cytometry. HS infusion caused a 7 +/- 2 mM rise in plasma Na+ levels that was sustained at 6 +/- 1 mM for 60 min. MAP was affected only in one subject. HS and NS infusion had little effect on neutrophil phagocytosis. After HS infusion, CD1lb expression of unstimulated neutrophils was 26 +/- 6% lower than before HS infusion, and that of fMLP-stimulated cells was 12 +/- 2% lower compared to pre-infusion values. NS infusion had no significant effects on neutrophil CD11b expression. L-selectin expression of unstimulated cells after HS infusion was 9 +/- 3% higher than in the pre-infusion samples. These data suggest that HS infusion could indeed affect human neutrophils by suppressing CD11b expression. Although modest in healthy subjects, this effect may be more pronounced in trauma patients where reduced neutrophil-endothelial cell interactions might lessen neutrophil-mediated tissue damage.

Adolescent↗
PubMed2001

Heparin and heparan sulfate inhibit extracellular signal-regulated kinase activation and myocardial cell hypertrophy induced by endothelin-1.

Heparan sulfate (HS) is one of the components of extracellular matrix and a potent anti-growth factor in various cells. Heparin has a similar structure to HS and is demonstrated to inhibit myocardial cell hypertrophy. We examined the intracellular signal mechanisms linking to the inhibitory effects of heparin and HS on endothelin-1 (ET-1)-induced hypertrophy in cultured rat neonatal myocardial cells (MCs). Heparin inhibited ET-1-induced c-fos mRNA expression. Heparin and HS inhibited ET-1-induced activation of c-fos promoter/enhancer in MCs. Although heparin and HS inhibited ET-1-induced activation of the wild-type c-fos serum response element (SRE), the activation of a mutated c-fos SRE that contains an intact binding site for the serum response factor (SRF) but lacks the ternary complex factor (TCF) binding site, was not inhibited. In addition, heparin and HS inhibited the activation of TPA response element (TRE). However, heparin did not inhibit the activation of cyclic AMP response element (CRE). Furthermore, heparin and HS inhibited ET-1-induced activation of extracellular signal-regulated kinase (ERK) and phosphorylation of Elk-1, which is one of the TCFs. These results indicate that heparin and HS inhibited ET-1-induced ERK activation, resulting in suppression of Elk-1 phosphorylation, and lead to inhibition of c-fos gene expression through SRF-independent manner. Moreover, heparin and HS inhibited ET-1-induced [3H] leucine incorporation. These results suggest that heparin and HS inhibit ET-1 induced myocardial cell hypertrophy through the inhibition of gene expression and protein synthesis.

Amino Acids↗
PubMed1976

Effect of sodium intake on aldosterone and corticosterone production, the serum sodium concentration and body weight in infant rats during weaning period.

1. The effect of a low salt (LS, 0.3% NaC1) and control (HS, 1% NaC1) diet on in vitro aldosterone and corticosterone production, the serum corticosterone level, the serum sodium concentration and adrenal and body weight was studied in 30-day-old male rats, some of which were weaned prematurely at the age of 15 days (PW) and some left with the female up to the end of the experiment (NW). 2. Aldosterone production in the control (HS-NW) animals was 1.07+/-0.07 mug/100 mg adrenal/hour (mean +/-S.E.M.), in HS-PW animals 0.6+/-0.07 (P less than 0.01), while in LS-NW and LS-PW animals it rose to 1.59+/-0.1 and 1.81+/-0.14 respectively. The effect of the salt regimen was significant in both the NW group (P less than 0.01) and the PW group (P less than 0.01). Premature weaning did not inhibit aldosterone production in LS-PW animals. 3. Corticosterone production in animals fed on the control diet was 1.81+/-0.16 mug corticosterone/100 mg adrenal/hour in HS-NW rats and 0.91+/-0.09 in the HS-PW group (P less than 0.01). On the low salt diet it fell to 1.4+/-0.11 in LS-NW rats (HW-NW) vs LS-NW: P less than 0.01) and to 0.4+/-0.06 in LS-PW animals (HS-PW vs LS-PW: P less than 0.01). The difference between LS-NW and LS-PW was likewise statistically significant (P less than 0.01). Changes in production were not accompanied by parallel changes in the serum corticosterone level, where an analysis of variance showed no significant difference. 4. The low salt diet reduced the serum sodium concentration in both NW and PW animals (HS-NW 132.9+/-0.86 mEd HS-PW 132+/-0.86, LS-PW 128.5+/-1.16: P less than 0.01). The differences between NW and PW animals were not significant. 5. A low salt intake also reduced the body weight both of animals left with the female (HS-NW vs LS-NW: P less than 0.01) and of prematurely weaned animals (HS-PW vs LS-PW: P less than 0.01). Early weaning significantly affected body weight in LS animals only, the body weight of LS-PW animals being significantly lower than that of LS-NW animals (P less than 0.02). 6. The results show that infant rats are hypersensitive to a low salt intake at the end of the weaning period and that this phenomenon is not mediated by lower reactivity of the zona glomerulosa and of its regulation.

Adrenal Glands↗
PubMed2004

High sensitivity C-reactive protein as a disease activity marker in rheumatoid arthritis.

OBJECTIVE: To elucidate the potential contribution of high sensitivity C-reactive protein (hs-CRP) testing in the assessment of disease activity in rheumatoid arthritis (RA). METHODS: We recorded clinical and psychological variables, the hs-CRP, and erythrocyte sedimentation rate (ESR) in 146 consecutive patients with RA. We analyzed the associations between the ESR and hs-CRP versus the other recorded variables. RESULTS: The median (interquartile range) ESR (mm/h) and hs-CRP (mg/l) were 15 (7-36) and 5 (2.3-13.9), respectively. Thirty-two (22%) patients had an hs-CRP < 2 mg/l, 61 (42%) an hs-CRP of 2-8 mg/l and 53 (36%) an hs-CRP > 8 mg/l. In patients with an hs-CRP of 2-8 mg/l, the swollen joint counts and the physician disease activity scales were higher, and remission rates were lower than in patients with an hs-CRP of < 2 mg/l. The hs-CRP was consistently more closely associated with disease activity, depression, and helplessness than was the ESR. CONCLUSION: High sensitivity CRP testing reveals systemic inflammation that is generally not detectable with routine CRP assays and that is associated with disease activity in RA.

Adult↗
PubMed1992

Recycling of transferrin receptors and heparan sulfate proteoglycans in a rat parathyroid cell line.

We examined recycling of heparan sulfate (HS) proteoglycans and transferrin receptor (Tf-R) in a rat parathyroid cell line. While extracellular Ca2+ concentration ([Ca2+]e) regulates the recycling of HS proteoglycans in parathyroid cells, such that HS proteoglycans only recycle when [Ca2+]e is lowered below physiological levels, recycling of Tf-R occurs equally well both in 0.05 mM (low) and 2 mM (high) [Ca2+]e. Inhibiting endocytosis chemically with phenylarsine oxide or at low temperature (4 degrees C) did not abolish the effects of changing [Ca2+]e on HS proteoglycans in the recycling compartment even though transport of HS proteoglycans from the Golgi complex to the cell surface was inhibited in low [Ca2+]e. Microtubules are not involved in the recycling of HS proteoglycans or of Tf-R since nocodazole did not affect these processes. Inhibiting the increase of intracellular Ca2+ by an intracellular Ca2+ chelator sustained recycling of HS proteoglycans even in the presence of high [Ca2+]e. These observations show that the exocytosis pathway of HS proteoglycans in the recycling compartment is specifically regulated by [Ca2+]e, whereas that for constitutive secretion is not. Therefore, the recycling of HS proteoglycans may be directly related to some functions of parathyroid cells regulated by [Ca2+]e. Although the mechanism by which [Ca2+]e regulates the exocytosis and recycling of HS proteoglycans is uncertain, it is suggested that an increase of intracellular Ca2+ is necessary, but not necessarily sufficient, for inhibiting their exocytosis.

Affinity Labels↗
PubMed1990

In vitro evaluation of 1-(2-chloroethyl)-1-nitroso-3-(2-hydroxyethyl)urea linked to 4-acetoxy-bisdesmethyltamoxifen, estradiol and dihydrotestosterone.

The anticancer efficacies of three 1-(2-chloroethyl)-1-nitroso-3-(2- hydroxyethyl)urea (HECNU) derivatives--4-acetoxybisdesmethyltamoxifen-1,4-hemisuccinate-H ECNU (4-OAc-BDMT-hs-HECNU), 17-beta-estradiol-1,4-hemisuccinate-HECNU (E2-hs-HECNU) and 17-dihydrotestosterone-1,4-hemisuccinate-HECNU (DHT-hs-HECNU)--are compared with their unlinked equimolar mixtures using the estrogen and androgen receptor positive cell line MCF-7. Following 72 h incubation at a concentration of 100 mumol/l, 4-OAc-BDMT-hs-HECNU and DHT-hs-HECNU have a growth inhibitory effect of 76% and 73%, respectively, whereas E2-hs-HECNU causes an inhibition of 55%. Within this time period, DHT-hs-HECNU (100 mumol/l) is more effective as compared to the unlinked equimolar combination of HECNU plus dihydrotestosterone; E2-hs-HECNU (100 mumol/l) is slightly more and 4-OAc-BDMT-hs-HECNU (100 mumol/l) is even less effective than the respective unlinked equimolar mixtures. At this concentration (100 mumol/l) the growth inhibitory effect of 4-OAc-BDMT-hs-HECNU is not antagonized by coincubation with estradiol.

Animals↗
PubMed1989

An unusual thiol-driven fumarate reductase in Methanobacterium with the production of the heterodisulfide of coenzyme M and N-(7-mercaptoheptanoyl)threonine-O3-phosphate.

An unusual fumarate reductase was purified from cell extracts of Methanobacterium thermoautotrophicum and partially characterized. Two coenzymes previously isolated from cell extracts, 2-mercaptoethane-sulfonic acid (HS-CoM) and N-(7-mercaptoheptanoyl)threonine-O3-phosphate (HS-HTP), were established as direct electron donors for fumarate reductase. By measuring the consumption of free thiol, we determined that fumarate reductase catalyzed the oxidation of HS-CoM and HS-HTP; by the direct measurement of succinate and the heterodisulfide of HS-CoM and HS-HTP (CoM-S-S-HTP), we established that these compounds were products of the fumarate reductase reaction. A number of thiol-containing compounds did not function as substrates for fumarate reductase, but this enzyme had high specific activity when HS-CoM and HS-HTP were used as electron donors. HS-CoM and HS-HTP were quantitatively oxidized by the fumarate reductase reaction, and results indicated that this reaction was irreversible. Additionally, by measuring formylmethanofuran, we demonstrated that the addition of fumarate to cell extracts activated CO2 fixation for the formation of formylmethanofuran. Results indicated that this activation resulted from the production of CoM-S-S-HTP (a compound known to be involved in the activation of formylmethanofuran synthesis) by the fumarate reductase reaction.

Disulfides↗
PubMed1977

Effects of cyclophosphamide and of busulfan on spleen colony-forming units and on hematopoietic stroma.

The effects of cyclophosphamide (CY) and busulfan (BU) on the hematopoietic stromal function (HS-P) of mouse marrow were evaluated. Stromal function of femoral marrow was assessed by implanting the test femur s.c. into an isogeneic host and determining the number of CFU-S in the implant 6 weeks later. Since the CFU-S have been shown previously to be primarily of host origin, this presumably measures the abilit- of donor hematopoietic sites to harbor host CFU-S. After injection of CY, the number of CFU-S in the marrow fell but recovered to normal within 6 weeks. The HS-P function fell to half-normal after 10 mg of CY and did not regenerate detectably in 6 weeks. On the other hand, 2 mg of BU i.p. caused a lesser initial decline in the number of CFU-S, but recovery was still incomplete after 6 weeks. BU given p.o. had a more marked effect on CFU-S and caused a significant decline in the HS-P function. Doses of CY (5 mg/dose) given intermittently appear to cause cumulative damage to HS-P function. HS-P function did not, in any experiment, recover significantly in the 6 weeks following the last dose of CY. This result suggests that large doses of the alkylating agent CY causes prolonged and perhaps permanent HS-P damage. This damage to the HS-P is cumulative when the CY is given at weekly intervals. Despite lack of HS-P recovery, CFU-S regenerate rapidly after CY therapy is stopped. On the other hand, BU also causes damage to the HS-P. However, even when BU is given at a dosage that does not significantly affect the HS-P, CFU-S recovery is delayed, suggesting that BU affects the CFU-S in a manner that differs qualitatively from that of CY.

Animals↗
PubMed1987

Chromatin structure and methylation state of a thyroid hormone-responsive gene in rat liver.

The gene for S14 in the rat codes for an mRNA which in lipogenic tissues (liver, fat, mammary gland) responds both to L-triiodothyronine and a high-carbohydrate, fat-free diet. In an effort to understand the molecular basis for the tissue-specific regulation of mRNA-S14 expression, we have examined the organization of this gene in chromatin. Specifically, we examined the distribution of DNase I-hypersensitive sites and DNA methylation sites associated with a 25-kilobase chromosomal domain containing the S14 gene. Our results show that DNase I preferentially digests four regions of the DNA flanking the 5' end of the hepatic S14 gene which have characteristics of DNase I-hypersensitive sites. The sites, identified as HS-1, HS-2, HS-3, and HS-4, are located at or adjacent to the site of transcription initiation and at 1.2, 7, and 8 kilobases upstream from this site, respectively. In lactating mammary gland where the S14 gene is also highly expressed and regulated by L-triiodothyronine, sites HS-1, HS-2, and HS-4 are present, but HS-3 is absent. No hypersensitive sites were detected either within the gene or flanking the 3' end of the gene. In brain, kidney, and spleen, tissues in which mRNA-S14 is expressed at levels less than or equal to 10% of that found in euthyroid liver, sites HS-1 and HS-3 were absent. Despite the marked effect of thyroid state on the abundance of hepatic mRNA-S14, no significant alterations were observed in the DNase I sensitivity of hepatic chromatin containing the S14 gene. Analysis of the DNA methylation pattern at HpaII and HhaI sites showed a positive correlation of hypomethylation of the gene and the contiguous flanking regions with S14 gene expression. All HpaII/MspI sites and most HhaI sites either within or flanking the S14 gene were undermethylated in liver and lactating mammary gland. Although thyroid status had no generalized effect on the site-specific DNA methylation state of the hepatic S14 chromosomal domain, one site (H3) situated in the second exon close to the 3' terminus of the S14 gene appeared to undergo demethylation in the transition from hypo- to euthyroidism. In essence, our results show that the 5' DNA flanking region of the S14 gene contains a tissue-specific DNase I-hypersensitive site which, although not influenced by thyroid status, appears essential for the expression of S14 and its regulation by L-triiodothyronine.(ABSTRACT TRUNCATED AT 400 WORDS)

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