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PubMed1977

Role of endogenous murine leukemia virus in immunologically triggered lymphoreticular tumors. I. Development and use of oncogenic cellfree preparations serially passaged in vivo.

Cellfree extracts (CFEs) prepared from (BALB/cJ X A/J)F1 (CAF1) and (BALB/cJ X C57BL/6J)F1 (CB6F1) mice in which a graft-versus-host reaction (GVHR) has been induced are known to be oncogenic, but only after a protracted latent period (mean, 16 mo). Serial passage of such CFEs in successive generations of syngeneic mice inoculated at birth led to the development of two separate oncogenic preparations, the CA serioes in CAF, mice and the CB series in CB6F, mice, in which the mean latent period was reduced to 6 and 12 months, respectively. Both oncogenic preparations contained infectious B-tropic murine leukemia virus (MuLV) and particles with the ultrastructural characteristics of MuLV. No other kind of virus particle was seen. When these preparations were injected into infant syngeneic mice, B-tropic MuLV could be detected in the reticular tissues as early as 2 weeks thereafter. The virus persisted in the reticular tissues and was present in the lymphoreticular tumors that subsequently developed. However, if the same preparation was injected into young adult recipients, there may have been transient MuLV replication, but the virus subsequently disappeared from the reticular tissues and no lymphoreticular tumors developed. Previous experiments showed that MuLV was present in CFEs prepared from CAF, animals with the GVHR but absent in those of normal control mice. Since the lymphoreticular tumors arising in mice with the GVHR were the same as those induced by the CA and CB MuLV preparations, it was concluded that tumorigenesis in mice with the GVHR was caused by endogenous B-tropic MuLV activated by the immunologic disturbance.

Animals↗
PubMed2002

Automated extraction of genomic DNA from medically important yeast species and filamentous fungi by using the MagNA Pure LC system.

A fully automated assay was established for the extraction of DNA from clinically important fungi by using the MagNA Pure LC instrument. The test was evaluated by DNA isolation from 23 species of yeast and filamentous fungi and by extractions (n = 28) of serially diluted Aspergillus fumigatus conidia (10(5) to 0 CFU/ml). Additionally, DNA from 67 clinical specimens was extracted and compared to the manual protocol. The detection limit of the MagNA Pure LC assay of 10 CFU corresponded to the sensitivity when DNA was extracted manually; in 9 of 28 runs, we could achieve a higher sensitivity of 1 CFU/ml blood, which was found to be significant (p <or= 0.004). DNA from all fungal species analyzed could be extracted and amplified by real-time PCR. Negative controls from all MagNA Pure isolations remained negative. Sixty-three clinical samples showed identical results by both methods, whereas in 4 of 67 samples, discordant results were obtained. Thus, the MagNA Pure LC technique offers a fast protocol for automated DNA isolation from numerous fungi, revealing high sensitivity and purity.

DNA, Fungal↗
PubMed1997

Biologic allergen assay for in vivo test allergens with an in vitro model of the murine type I reaction.

BACKGROUND: The determination of the biologic activity of allergenic extracts in human beings is limited for ethical and practical reasons. The establishment of a simplified in vitro model, which mimics a main event of the type I reaction, should provide true benefit for manufactures, researchers, and clinicians. OBJECTIVE: This study was designed to develop and evaluate a mediator release assay based on rat bosophil leukemia cells for the purpose of investigating allergenic extracts. METHODS: Rat basophil leukemia cells were passively sensitized with murine IgE raised against allergens and stimulated by serial dilutions of allergenic extracts in a dose-related manner. The allergen-specific degranulation was monitored by measuring the release of beta-hexosaminidase. RESULTS: The investigation of standardized commercial allergen products for in vivo diagnostics (birch pollen, cat dander, and bee venom) allowed a quantitative description of differences in biologic activity in accordance with the declared activity units. The Fel d 1 content was determined in 17 cat dander extracts and correlated well with the results of a two-site binding ELISA (r = 0.93, log/log). Extremely low allergen amounts in the range of 10 to 100 pg/ml could be easily detected. Moreover, the cross-reactivity pattern of patients allergic to birch pollen could be reproduced with extracts of hazel, alder, apple, and celery. CONCLUSION: The assay is suitable for supplementing quality control of allergenic extracts and for the determination of biologic activity of final allergen products. As a research tool, it allows the study of IgE cross-linking properties of modified and recombinant allergens at an early stage before they are tested in human beings.

Allergens↗
PubMed2004

Comparative evaluation of in-vitro effects of Brazilian green propolis and Baccharis dracunculifolia extracts on cariogenic factors of Streptococcus mutans.

Streptococcus mutans triggers dental caries establishment by two major factors: synthesis of organic acids, which demineralize dental enamel, and synthesis of glucans, which mediate the attachment of bacteria to the tooth surface. Propolis is a natural product that may prevent dental caries. Baccharis dracunculifolia DC (Asteraceae), a native plant from Brazil, is the most important botanical origin for the production of green propolis (Brazilian propolis) by honeybees. However, whether B. dracunculifolia (Bd) has an anticariogenic effect, like green propolis, remains unknown. Herein, we have made a comparative evaluation of the effects of extracts from green propolis and Bd on the glucan synthesis and acidogenic potential of S. mutans. The inhibitory effects of the extracts on bacterial acid production were evaluated through the potentiometric measurement of pH from bacterial suspensions treated with serial concentrations of both extracts. Besides presenting close inhibitory values at the same concentration range, Bd leaf rinse and green propolis extracts had similar IC(50) values (0.41 and 0.34 mg/ml, respectively). Both extracts produced a bacteriostatic effect on S. mutans cultures at a concentration of 0.40 mg/ml. Estimated inhibitory values of green propolis and Bd leaf rinse extracts on the synthesis of insoluble glucans (IC(50)=12.9 and 25.0 microg/ml, respectively) and soluble glucans (IC(50)=50.4 and 49.1 microg/ml, respectively) were not significantly different from each other at p<0.05. The results demonstrate that Bd leaf rinse and green propolis extracts have similar inhibitory effects on the S. mutans cariogenic factors evaluated herein, and allowed us to suggest that Bd leaves may be a potential source for pharmaceutical products employed for this purpose.

Anti-Infective Agents↗
PubMed1988

Calcitonin-like immunoreactivity and calcitonin gene expression in the placenta and in the mammary gland of the rat.

Recently, the presence of monomeric CT in plasma and milk was reported by others in a lactating woman surgically thyroidectomized. Similarly, the placenta was thought to be a possible source of CT. Since such findings were based exclusively on immunological arguments, we have investigated the CT gene expression in these rat tissues. CT mRNAs were detected by dot-blot hybridization of total RNAs extracted from rat tissues with a 32P-labelled human CT cDNA probe. Subcellular fractions of each tissue were screened for CT-like immunoreactivity using two different antibodies. With one antibody, extracts of the mammary gland and placenta both produced full displacement of labelled human CT from the antiserum and serial dilutions of the extracts gave displacement curves parallel to that of synthetic human CT, which suggests immunological similarity. However, dilution curves were not parallel for the second antibody, and for both antisera, CT-like immunoreactivity was found in all subsellular fractions from nuclei to cytosols. Immunoprecipitation of translation products from poly (A)+RNAs of placenta showed two major bands around 30 kD. Under stringent conditions, the weak hybridization of placental RNAs seen by dot-blot under less stringent conditions disappeared. Northern analyses of total RNAs from the placenta failed to detect mRNA of 1 k base size like in thyroid glands, but hybridization under weak stringent conditions occurred with larger mRNAs (around 4.4 and 2.4 k bases). Immunoprecipitation of translation products from mRNAs of rat mammary glands showed three major bands around 46, 30 and 20 kD. Dot-blot hybridization of total RNAs extracted from mammary glands was also negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Evaluation of the antiparasitic effect of aqueous garlic (Allium sativum) extract in hymenolepiasis nana and giardiasis.

The effect of serial dilutions of crude garlic (Allium sativum) extract on adult Hymenolepis nana was studied to detect the minimal lethal concentration which was found to be 1/20. A. sativum was tried in the treatment of 10 children infected with H. nana and 26 infected with G. lamblia as 5 ml crude extract in 100 ml water in 2 doses per day, or commercial preparation (0.6 mg capsules) 2 capsules twice/day for 3 days. A sativum was found to be efficient, safe and shortens the duration of treatment. The possible mode of action of A. sativum and the correlation between the clinical and parasitological findings were discussed.

Animals↗
PubMed1978

Cure of acromegaly by operative removal of an islet cell tumor of the pancreas.

We studied a 30 year old woman in whom acromegaly was cured by operative removal of a large cystic beta cell adenoma of the pancreas. We detected substantial amounts of immunoreactive human growth hormone (hGH)-like activity in a tumor tissue extract. Extracts of the tumor and a normal human pituitary gland eluted from a Sephadex G-75 column in two identical peaks. Serial dilutions of the tumor extract displaced radioactive 125I hGH parallel to a standard curve. Surprisingly, an extract of a normal human pancreas contained large amounts of hGH-like activity and gave results similar to those of the tumor extract on gel chromatography and on serial dilution displacement in the growth hormone immunoassay. Paper electrophoretic studies of 125I hGH after incubation with normal pancreatic and tumor extracts with and without enzyme inhibitors suggested that pancreatic proteolytic enzymes damaged the 125I hGH used in growth hormone radioimmunoassay and produced a false detection of hGH.

Acromegaly↗
PubMed1979

[Radioimmunoassay of ADH in human urine (author's transl)].

A simple efficient procedure for extracting and concentrating arginine-8-vasopressin (AVP) from urine has been coupled with a specific and sensitive radioimmunoassay in order to measure antidiuretic hormone (ADH) excretion in normal humans under various physiological stimuli. Antisera have been raised in rabbits injected with lysine-vasopressin (LVP) or AVP coupled with bovine serum albumin. The antiserum selected for the assay which inhibits the antidiuresis induced in the rat by AVP is used at a final dilution of 1 : 50,000 and possesses a high association constant of 1 x 10(11) 1.mol-1. The limit of detection of the RIA system is 0.5 micronUI/ml of urine (1.25 pg). Urinary ADH has been extracted from urine by Miller and Moses method. Mean recovery of added vasopressin averaged 90.2% +/- 11 (SD) and assay of serial dilutions of such extracts showed that they behave in the assay system in the same way as synthetic AVP standards. Moreover comparison of the results obtained by the RIA to those given by the biological method using the ethanol anesthetized rat showed excellent correlation (r = 0.9 p less than 0.001). Under ad libitum fluid and food intake, mean daily urinary excretion of AVP (uncorrected for recovery) determined in 22 subjects was found to be 30.58 +/- 11.64 mU/h with no significant difference between men and women. In response to an oral waterload ADH became undetectable at the peak of diuresis. Following a 16 hr fluid deprivation, ADH rose moderately. A significant correlation has been found between urine osmolality and AVP excretion rate.

Adult↗
PubMed1996

Assessment of metal extract toxicity on human lymphocytes cultured in vitro.

In this study the toxic effects of chromium, nickel, and cobalt extracts on in vitro cultured lymphocytes were evaluated. Graphite furnace atomic absorption spectrometry was used to measure the ion concentration. After serial dilution of the extracts, the viability of lymphocytes at 24, 48, and 72 h was estimated by flow cytometry, including propidium iodide staining and light scatter property assessment, and by MTT reduction test. The results of the investigation allowed us to conclude that 1) standardization of the procedure for preparing extracts is fundamental to obtaining repeatability of results; 2) the toxicity of an extract cannot be evaluated with a single viability assay; a combination of functional and structural tests is required; 3) when methods based on enzymatic reactions are performed, e.g. MTT test, it is advisable to replace the extract containing metal ions with fresh medium in order to avoid any interference with viability testing; 4) the amount of Co and Ni in the extract is similar, but the Cr release is very poor; 5) the lower toxicity of Cr extract probably is due to the lower ion concentration; 6) the assessment of 50% cytotoxic concentration (TC50) allows quantification of materials toxicity and comparison of various metals; and 7) the determination of a noncytotoxic concentration, i.e., a concentration lower than TC10, is required for subsequent investigation of cell functions because such studies can be carried out only on viable cell population.

Cell Survival↗
PubMed1974

A radioimmunoassay for measurement of 3,3',5'-triiodothyronine (reverse T3).

A highly specific antiserum to 3,3',5'-triiodothyronine (reverse T(3), rT(3)) was prepared by immunization of rabbits with D,L-rT(3)-human serum albumin conjugate. Of the various thyroid hormone derivatives tested, only 3,3'-diiodothyronine (3,3'-T(2)) cross-reacted significantly (10%) with rT(3)-binding sites on the antiserum, while thyroxine (T(4)) and triiodothyronine (T(3)) cross-reacted by less than 0.1%. The antiserum was used in a simple, sensitive, precise, and reproducible radioimmunoassay (RIA) for measurement of rT(3) in ethanolic extracts of serum. The dose-response curves of inhibition of the binding of [(125)I]rT(3) to antibody obtained by serial dilutions of serum extracts were essentially parallel to the standard assay curve. Recovery of nonradioactive rT(3) added to serum before extraction averaged 93%. Serum rT(3) concentrations were found to be (mean+/-SD) 41+/-10 ng/100 ml in 27 normal subjects, 103+/-49 ng/100 ml in 22 hyperthyroid patients, 19+/-9 ng/100 ml in 12 hypothyroid patients, and 54+/-7 ng/100 ml in five subjects with elevated serum thyroxine-binding globulin: the values in each of the latter three groups of individuals were significantly different from normal. Reverse T(3) was detected regularly in normal or supranormal concentrations in serum of 12 hypothyroid patients rendered euthyroid or mildly hyperthyroid by treatment with synthetic T(4). It is suggested that serum rT(3) values noted here should be taken to reflect the relative changes in serum rT(3) rather than its absolute values in health and thyroid disease. True serum rT(3) may be somewhat different because: (a) D.L-rT(3) employed in the standard curve and L-rT(3) present in human serum may react differently with anti-D,L-rT(2). (b) Even though 3,3'-T(2), which cross-reacted 10% in rT(3) RIA, has been considered unlikely to be present in human serum, it may circulate in low levels. (c) Cross-reaction of T(4) in rT(3) RIA of 0.06% although small, could contribute to RIA estimates of rT(2); the effect of T(4) would be particularly important in case of serum of hyperthyroid patients. Thus, serum rT(3) concentration in hyperthyroid patients averaged 89+/-48 mug/100 ml after correction for cross-reaction effects of T(4): this value was about 14% lower than that before correction (see above). Serum rT(3) concentration in cord sera of seven newborns averaged 136+/-19 ng/100 ml; it was clearly elevated and within the range of values seen in hyperthyroid patients. This was the case when the mean T(4) concentration in the newborn cord sera was moderately higher than normal and about one-half that in hyperthyroid patients, whereas serum T(3) was markedly below the normal adult level. A Pronase hydrolysate of thyroglobulin prepared from pooled normal thyroid glands contained 0.042, 3.0, and 0.16 mug/mg protein of rT(3), T(4), and T(3), respectively. The various data suggest that: (a) rT(3) is a normal component of human serum and thyroglobulin: (b) peripheral metabolism of T(4) is an important source of the rT(3) present in serum: (c) peripheral conversion of T(4) to T(3) and rT(3) may not necessarily be a random process.

Adult↗
PubMed1982

Thyrotropin-like immunoreactivity in the pituitary and three brain regions of the female rat: diurnal variations and the effect of thyroidectomy.

A method for extracting and assaying TSH-like immunoreactivity (TSH-LI) in regions of the central nervous systems (CNS) of individual rats was developed and validated. Serial dilutions of tissue extracts paralleled dilutions of purified rat TSH standard in the RIA, and tissue TSH-LI comigrated electrophoretically with TSH standard. TSH-LI was measured in the pituitary (PIT), the medial basal hypothalamus (MBH), the remainder of the hypothalamus (HYPO), and the cerebral cortex (CC). Female rats were maintained on a normal 12-h light, 12-h dark cycle (LD; onset of light, 0730 h) or an inverted 12-h light, 12-h dark cycle (DL; onset of light, 1930 h) for 3 weeks and then killed at 4-h intervals throughout the day. Another group of rats on the LD photoperiod were either thyroidectomized or sham thyroidectomized and killed 3 weeks later at 1000 h. Diurnal variations of TSH-LI were present in the PIT, MBH, HYPO, and CC on the LD photoperiod (P less than 0.05). The acrophases of MBH, HYPO, and CC TSH-LI diurnal variations occurred soon after the onset of darkness, whereas the PIT TSH-LI variation peaked soon after the onset of light. Inverting the photoperiod inverted the PIT TSH-LI diurnal variation, but central nervous system TSH-LI variations were not phase shifted after 3 weeks on the inverted photoperiod. Thyroidectomy elevated plasma and MBH TSH-LI levels (P less than 0.05), but PIT, HYPO, and CC TSH-LI levels were not significantly different from those in sham-operated controls. These results indicated that brain TSH concentrations could change under different physiological states independently of changes in PIT or plasma TSH. Although brain TSH exhibited diurnal variations, the data suggested that the phase of these variations was not set by the light-dark cycle.

Animals↗
PubMed1997

Comparison of four RNA extraction methods for the detection of porcine reproductive and respiratory syndrome virus by RT-PCR.

We compared four commercial RNA isolation methods for the extraction of RNA from porcine reproductive and respiratory syndrome virus (PRRSV). The sensitivity of the methods was determined by extraction of RNA from serial 10-fold dilutions of PRRSV diluted in PRRSV-negative porcine serum or in Eagle's minimal essential medium (EMEM) followed by amplification of extracted nucleic acids by RT-PCR. The PCR products were detected in ethidium bromide-stained agarose gels. The QIAamp viral kit, which is based on binding of RNA to silica particles, was the most sensitive, allowing the detection of an equivalent of 10 TCID50 of virus in 100 microliters of serum or EMEM. The QIAamp-tissue and the TRIzol LS kits detected 100 TCID50 per 100 microliters in both diluents whereas Ultraspec-3 detected 100 TCID50 of virus in EMEM and 1000 TCID50 in serum. These results indicate that QIAamp viral kit has a higher sensitivity for RT-PCR analysis of PRRSV.

Animals↗
PubMed1996

Cerebral extraction of oxygen, lactate production, and perfusion pressure in gunshot wound to the head: case report.

A case of gunshot wound to the head is presented, in which the patient made a satisfactory recovery after a prolonged period of elevated intracranial pressure and increased cerebral extraction of oxygen. Even though cerebral extraction of oxygen was increased in the most acute phase, the arteriojugular lactate difference was never abnormally decreased (ischemic). This finding indicated that, in this patient, increased cerebral extraction of oxygen was not sufficient to result in global cerebral ischemia (increased cerebral lactate production). To our knowledge, this is the first report on frequent serial assessment of cerebral extraction of oxygen and lactate production in severe penetrating head injury.

Adult↗
PubMed1986

L-dopa stimulates release of hypothalamic growth hormone-releasing hormone in humans.

A sensitive RIA for human GH-releasing hormone-(1-44)-NH2 [hGHRH-(1-44)-NH2] was developed which allows its measurement in human plasma extracts. The assay did not detect hGHRH-(1-37)-OH or hGHRH-(1-40)-OH. A method to extract hGHRH from plasma was developed using silicic acid and acid-acetone, by which recovery of synthetic hGHRH-(1-44)-NH2 from plasma averaged 74.3%. Serial dilutions of plasma extracts gave an inhibition curve parallel with that of synthetic hGHRH-(1-44)-NH2 in the RIA system. On Sephadex G-50 columns, hGHRH-like immunoreactivity (hGHRH-LI) in plasma extracts eluted as a single peak corresponding to hGHRH-(1-44)-NH2. This hGHRH-LI peak, when subjected to reverse phase HPLC, emerged at the position where hGHRH-(1-44)-NH2 was eluted. hGHRH-LI was detectable in the peripherally circulating plasma of all subjects tested. The mean basal level of plasma hGHRH-LI in normal subjects was 9.4 +/- 0.7 (+/- SE) pg/ml (n = 22; range, 2.8-18.1 pg/ml), comparable to the basal plasma hGHRH-LI concentration in patients with hypothalamic lesions (11.3 +/- 1.1 pg/ml; n = 7). Oral administration of L-dopa (0.5 g) caused a significant increase in both plasma hGHRH-LI and GH levels in normal subjects, and the plasma hGHRH-LI peak slightly preceded or coincided with that of plasma GH in individual subjects. There was also a significant correlation between plasma hGHRH-LI and the GH rises after L-dopa administration when their net increments were compared. All of the patients with hypothalamic lesions had significant increases in plasma GH after hGHRH-(1-44)-NH2 injection (1 microgram/kg BW, iv), indicating the presence of functioning somatotrophs in their pituitaries. When L-dopa was orally administered to these patients, neither plasma hGHRH-LI nor GH concentration changed throughout a 120-min observation period. These findings suggest that 1) hGHRH, immunologically and chromatographically indistinguishable from synthetic hGHRH-(1-44)-NH2, is detectable in peripheral plasma in humans; 2) L-dopa stimulates the release of hypothalamic hGHRH, alterations of which are reflected in changes in peripheral levels; and 3) the source of circulating hGHRH is not restricted to the hypothalamus, since hGHRH-LI is present in the peripheral plasma of patients with hypothalamic lesions in amounts similar to those found in normal subjects.

Administration, Oral↗
PubMed1991

Distribution and characterization of immunoreactive growth hormone (GH) in the pituitary of the frog Rana ridibunda using an antiserum against purified bullfrog GH.

The presence of growth hormone (GH) in the pituitary of the frog Rana ridibunda was investigated using an antiserum raised against purified bullfrog GH. The immunofluorescence technique revealed that GH-containing cells are exclusively located in the dorsal area of the distal lobe of the pituitary. The relative abundance of these GH-positive cells, which correspond to acidophilic type 2 cells, was 18 +/- 1% of the total population of endocrine cells of the pars distalis. Frontal sections of the distal lobe indicated that GH-producing cells are distributed in an arc of a circle occupying all of the dorsal part of the lobe. At the electron microscopic level, GH-immunoreactive material was sequestered in large polymorphic granules (200-700 nm). GH was quantified in R. ridibunda pituitary extracts using a radioimmunoassay for bullfrog GH. The displacement curves obtained with serial dilutions of pars distalis extracts were not strictly parallel to the standard curve made with purified bullfrog GH. In contrast, Western blot analysis revealed that GH from R. ridibunda had a molecular weight (22 kDa) similar to that of bullfrog GH. In the pars distalis, the apparent amount of GH was 0.61 +/- 0.14 microgram per lobe, corresponding to 0.92 +/- 0.17% of total proteins in the extracts. In contrast, frog neurointermediate lobe or hypothalamus did not contain significant concentrations of immunoreactive GH (less than 0.006% of total proteins in the extracts). Taken together, these results validate the use of an antiserum to bullfrog GH to investigate the regulation of GH secretion in R. ridibunda.

Animals↗
PubMed1994

Plasma kinins increase after angiotensin-converting enzyme inhibition in human subjects.

1. In patients treated with angiotensin-converting enzyme inhibitors, kinin-related effects have been postulated repeatedly, but information on changes in plasma kinin levels in these patients is sparse. Difficulties in the measurement of plasma kinins account for this, at least in part. 2. The main purpose of the present study was to investigate, in normal human subjects, the effect of the angiotensin-converting enzyme inhibitor quinapril on plasma kinins. 3. High-affinity antisera (Kd < 10(-11) mol/l) of C-terminal specificity were raised in rabbits for radioimmunoassay of immunoreactive kinins activating the bradykinin B2-receptor, and three different liquid- and solid-phase extraction methods for plasma kinins were evaluated. Ethanol and subsequent petroleum ether extraction of 5-40 fmol of bradykinin added to plasma yielded recoveries of 39 +/- 16% (mean +/- SD); normal kinin levels in human plasma were 18.6 +/- 3.3 pmol/l (mean +/- SEM). Solid-phase extraction on urea-equilibrated phenylsilylsilica produced recoveries of 89 +/- 5% and normal values of 36.4 +/- 18 pmol/l. Finally, with an assay based on ethanol extraction alone, recoveries of 100 +/- 16% and normal values of 16.8 +/- 5.8 pmol/l were obtained, with a detection limit of 1.5 fmol/ml of plasma. Blanks were below the detection limit. Serial dilution of plasma extracts (n = 4) provided linear kinin concentrations (r = 0.99). For two different plasma pools, coefficients of variation for within-assay precision were 16.7% and 21.7%, respectively. Between-assay coefficients of variation were 12.8% and 17.4%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1998

A radioimmunoassay for the determination of angiotensin II in elasmobranch fish.

A homologous radioimmunoassay was developed to determine the concentration of angiotensin II (Asn1, Pro3, Ile5)-Ang II) in elasmobranchs. Cross-reactivity with elasmobranch angiotensin I and other heterologous angiotensins was high and therefore all potentially cross-reacting angiotensins were separated by high performance liquid chromatography after prior extraction with Sep-Pak C18 cartridges. The validity of the assay for the determination of elasmobranch Ang II was demonstrated by parallelism with a series of Ang II standards with serially diluted elasmobranch plasma extracts. Overall recovery of elasmobranch Ang II added to a plasma pool was 75.1 +/- 5.2%. Plasma Ang II concentrations measured by our RIA were similar in fish adapted to 70, 100, or 120% SW at 139 +/- 20.1, 109 +/- 15.3, and 119 +/- 16.3 fmol . ml-1, respectively.

Adaptation, Physiological↗