Ciliary microtubule capping structures contain a mammalian kinetochore antigen

Structures that cap the plus ends of microtubules may be involved in the regulation of their assembly and disassembly. Growing and disassembling microtubules in the mitotic apparatus are capped by kinetochores and ciliary and flagellar microtubules are capped by the central microtubule cap and distal filaments. To compare the ciliary caps with kinetochores, isolated Tetrahymena cilia were stained with CREST (Calcinosis/phenomenon esophageal dysmotility, sclerodactyly, telangiectasia) antisera known to stain kinetochores. Immunofluorescence microscopy revealed that a CREST antiserum stained the distal tips of cilia that contained capping structures but did not stain axonemes that lacked capping structures. Both Coomassie blue-stained gels and Western blots probed with CREST antiserum revealed that a 97-kD antigen copurifies with the capping structures. Affinity-purified antibodies to the 97-kD ciliary protein stained the tips of cap-containing Tetrahymena cilia and the kinetochores in HeLa, Chinese hamster ovary, and Indian muntjak cells. These results suggest that at least one polypeptide found in the kinetochore is present in ciliary microtubule capping structures and that there may be a structural and/or functional homology between these structures that cap the plus ends of microtubules.

[A study of clinical safety of lithium levels in the serum and erythrocytes]

A correlative and regression analysis of the serum and erythrocyte lithium level (SLL and ELL) were investigated on 135 times in 31 patients with lithium therapy. It was found that the levels of both were positively-correlated with statistical significance (r = 0.8174). The levels of both and their ratio in relation to clinical manifestation were studied. It was showed that while ELL exceeded 1 mEq/L, SLL exceeded 1.2 mEq/L and the ratio between ELL and SLL exceeded 0.8: 1, symptoms of lithium intoxication occurred in 4 or 5 cases. It is suggested that lithium intoxication may possibly occur when SLL and ELL as well as their ratio reaches the above-mentioned criterion.

Characterization of phytotoxicity of metal engraving effluent samples

Two effluent samples were collected from an acid bath of a metal engraving industry. Sample A was lime-treated to pH 6 and sample B, pH 9. Zn concentrations in samples A and B were 1207 and 4.24 mg L(-1), respectively. Both samples A and B caused 100% inhibition on millet seed germination. Sample A was more toxic than B. The 60% concentration of sample A caused 96% inhibition, whereas the 60% concentration of sample B caused 60% inhibition. The toxicity of sample B was not likely due to the presence of cyanide and zinc ions. The results of using various adsorbents and resins for the effluent treatment showed that only powdered activated carbon was partially effective in toxicity removal. By a combination of treatment methods, including using sodium hydroxide precipitation and carbon column adsorption, toxicity removal was calculated to be 29%.

The use of phytotoxicity tests (common duckweed, cabbage, and millet) for determining effluent toxicity

The objective of this study was to use higher plants for detecting effluent toxicity. Eight effluent samples were obtained from three industrial sources prior to their entry into a sewer system. The tests were the duckweed reproduction test, and root growth tests using cabbage and millet. The results of repeated phytotoxicity tests were reproducible. Of the three industrial sources, the effluent samples from a specialty chemical industry were the most toxic. For two samples from this source, the IC50 values (the concentrations which caused 50% inhibitory effect) for duckweed were less than 1.6% effluent concentration. The samples from an agricultural product utilization plant were the least toxic. For these samples, root growth tests failed to obtain IC50 values while the duckweed tests showed IC50 values of 91 and 43% effluent concentration. Among the three types of tests conducted, the duckweed reproduction test showed the greatest sensitivity to effluent toxicity, while root growth tests using cabbage and millet had mixed results. Duckweed is recommended as a part of a battery of tests for effluent toxicity.

Gestational trophoblastic disease: a case-control study from the People's Republic of China

A case-control study involving 331 patients with complete hydatidiform mole and 662 community controls matched to the cases on age and timing of pregnancy was conducted in Beijing, China. A history of a term birth was associated with reduced risk (odds ratio = 0.6, 95% confidence interval 0.4 to 0.9), with some evidence of further decrease with multiple births. Previous spontaneous abortions were not related to risk, although those with a prior induced abortion were at elevated risk, particularly if two or more abortions were involved (odds ratio = 2.8, 95% confidence interval 1.4 to 5.7). A history of having sought medical advice for infertility was associated with reduced risk (odds ratio = 0.5, 95% confidence interval 0.2 to 0.8), but those who reported use of herbal medicines during a first trimester of a previous pregnancy were at excess risk (odds ratio = 2.2, 95% confidence interval 1.3 to 3.6). In addition, a statistically significant trend in risk was observed with years of oral contraceptive use (odds ratio = 2.6, 95% confidence interval 0.9 to 6.9 for greater than or equal to 4 years of use). Dietary habits and family histories of cancer or trophoblastic disease were not related to risk in this study.

Mechanism of action of colchicine. VI: Effect of colchicine on generation of leukotriene B4 by human polymorphonuclear leukocytes

Three microtubule-disruptive agents (colchicine, oncodazole, and vinblastine) are shown to suppress ionophore A23187-induced generation of LTB4 in a dose-related manner. The slopes of the dose-response regression lines were similar for the three drugs. Trimethyl-colchicinic acid has no effect on LTB4 generation. The suppressive effect of colchicine (1 x 10(-6) M) can be blocked completely by taxol (1 x 10(-6) M) which promotes and stabilizes microtubule assembly. The data suggest that colchicine suppresses the generation of LTB4 via its effect on microtubules.

[Chemical studies on the constituents of radix Ophiopogonis]

In this paper four compounds isolated from Radix Ophiopogonis are described. Their structures have been identified as beta-sitosterol (I), 6-aldehydo-7-methoxy-isoophiopogonanone B (II), beta-sitosterol-beta-D-glucopyranoside (III) and 1-borneol-beta-D-apisyl-beta-D-glucopyranoside (IV) on the basis of spectral data and hydrolytic reaction.

Environmental factors and Parkinson's disease: a case-control study in China

We studied the role of environment in the development of Parkinson's disease (PD) in China, where industrialization is relatively recent and the population geographically stable. Using a case-control method, we investigated the relationship between PD and exposure to the following factors before disease onset: place of residence, source of drinking water, environmental and occupational exposure to various agricultural and industrial processes. Occupational or residential exposure to industrial chemicals, printing plants, or quarries was associated with an increased risk of developing PD. In contrast, living in villages and exposure to the common accompaniments of village life, wheat growing and pig raising, were associated with a decreased risk for PD. PD cases and controls did not differ with respect to other factors investigated. These findings are consistent with the hypothesis that environmental exposure to certain industrial chemicals may be related to the development of PD.

Heterogenous response of primary cultured bone marrow cells of patients with different varieties of leukemia to differentiation inducers

The in vitro induced differentiation of a number of human leukemia cell lines by chemical inducers not only provides a valuable model system for the study on the mechanism of hematopoietic cell proliferation and differentiation at both cellular and molecular levels, but also reveals a new prospect in the treatment of leukemia. In order to find out the possibility of applying inducing agents to the patients with various types of leukemia, the bone marrow cells in primary culture from 50 patients with leukemia were tested for their inducibility in response to the inducers. Only M3 leukemia bone marrow cells can be markedly induced by retinoic acid to the myeloid terminal cells with positive NBT reduction while the cells of other types respond with uncertainty. TPA is able to cause a macrophage-like differentiation in bone marrow cells of all types of leukemia except M1. However, the leukemic cells of chronic myelogenous leukemia in lymphocytic blast crisis will lose response to TPA. The cultured bone marrow cells of acute lymphocytic leukemia respond neither to retinoic acid nor to TPA. Homoharringtonine, a chemotherapeutic drug used in the so-called HOAP regimen for acute nonlymphocytic leukemia, seems to possess the capability of inducing HL-60, the promyelocytic leukemia cell line, to NBT positive myeloid terminal cells, although the inducing effect is weaker than retinoic acid.

Evidence for a latent form of protein phosphatase 1 associated with cardiac myofibrils

Detergent-purified myofibrils from bovine heart contained very little spontaneously active protein phosphatase 1 activity. Phosphatase 1, extracted from the myofibrils by freeze-thawing in the presence of 500 mM KCl, was markedly activated by cobalt/trypsin treatment. Myofibril phosphatase 1 was separated from phosphatase 2A by chromatography on heparin-Sepharose. The phosphatase 1 was isolated in a latent form. Pretreatment with trypsin released free catalytic subunit and increased activity about 25-fold. Addition of cobalt with the trypsin increased activity another 2-fold. The latent myofibril phosphatase 1 did not appear to be the same as previously characterized forms of protein phosphatase 1. We suggest that cardiac myofibril phosphatase 1 contains a unique inhibitory subunit which directs the enzyme to the myofibril and regulates the dephosphorylation of myofibril phosphoproteins.

Calcium antagonists in prevention of hypertension and stroke in stroke-prone spontaneously hypertensive rats

To investigate the effect of Calcium antagonists (Ca-An) with different tissue specificity in the development of hypertension and stroke in salt-loading SHRSP, three experiments were conducted. In experiment I (1), 50 8-week-old male SHRSP were divided into three groups and given nifedipine (NF, 32 mg/kg/day), menidipine (MN 32 mg/kg/day) and placebo (control group) respectively. In the control group 83.3% (15/18) died of stroke and 17 showed renal vascular sclerosis. Their average lifespan was 84 days. NF and MN significantly reduced systolic blood pressure (SBP), and no stroke of renal vascular sclerosis developed. In experiment I (2), 54 7-week-old male SHRSP were divided into three groups (18 in each group). They were treated with nimodipine (NM) 20 mg/kg/day, 2 mg/kg/day and placebo respectively. NM (20 mg/kg/day) markedly lowered SBP and postponed the onset of stroke. Only 11% died in 17 weeks. NM (2 mg/kg/day did not lower SBP but postpond the onset of stroke. In experiment II (1), 29 10-week-old female SHRSP were divided into three groups: Group A was given NF 32 mg/kg/day, group B was parathyroidectomized (PTX) and group C served as control. PTX group did not lower SBP but could postpone the onset of stroke. In experiment II (2), 33 male SHRSP were divided into three groups and ticated as described above in experiment II (1) (11 in each group). Seven weeks after the experiment, the brain blood flow of NF group was significantly greater (67.5%) than that of the control and PTX groups. In experiment III, 27 7-week-old male SHRSP were divided into three groups as described above in experiment I (2).(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular emission and electronic structure of associated chlorophyll a

We report the wavelength-selective Raman and fluorescence spectra of monomeric and aggregate species of chlorophyll a in solution. The excitation profile for the molecular emission of the various chlorophyll complexes permit the construction of part of the electronic energy level diagram. For a T-shaped dimeric chlorophyll a, pseudo-exciton splittings of 667 cm−1 in the Soret and 397 cm−1 in the Qy bands are obtained.

Himbacine recognizes a high affinity subtype of M2 muscarinic cholinergic receptors in the rat cerebral cortex

The in vitro receptor binding properties of a muscarinic antagonist himbacine have been studied in rat cerebral cortical, cardiac and ileal membranes. Himbacine displayed high affinity (KH = 2.94 nM) for 19%, and low affinity (KL = 71.2 nM) for the remaining muscarinic receptors in rat cerebral cortex. This high affinity of himbacine agrees with its affinity for the 62% of cerebral cortical [3H]AF-DX 116 binding sites (KH = 2.30 nM). The affinity of himbacine for cardiac receptors (Ki = 9.06 nM) and ileal receptors (Ki = 12.4 nM) was the same. Therefore, himbacine appears to be a high-affinity M2-selective ligand which recognizes a subtype of M2 receptors in the cerebral cortex.

Severe obstructive sleep apnea in a child with osteopetrosis

The clinical features of a 5-year-old patient with osteopetrosis and severe obstructive sleep apnea are presented. The patient responded to tonsillectomy, adenoidectomy, uvulectomy, and tracheostomy. The tracheostomy was later removed. Osteopetrosis, while rare, may be added to the list of causes of obstructive sleep apnea.

Effects of gossypol on the activity of kidney (Na+ + K+)-ATPase and the functions of erythrocyte membrane

Gossypol extracted from cottonseed oil, reputed to exert contraceptive action in males, may induce a side effect of hypokalemia. The cellular and molecular mechanisms by which gossypol produces hypokalemia are not quite understood. We have examined the inhibitory effect of gossypol on the activity of (Na+ + K+)-ATPase purified from the outer medulla of rabbit kidney, the half maximal inhibitory concentration (IC50) is 6.5 micron. The kinetic studies using this enzyme preparation show that gossypol is noncompetitive with ATP, Mg2+, Na+ and K+ with apparent Ki of 15.0, 13.0, 14.0 and 4.4 micron, respectively. On the other hand, in order to estimate the effects of gossypol on membrane transport of intact cells, we have investigated the effects of gossypol on the activity of (Na+ + K+)-ATPase, membrane integrity and permeability of human erythrocytes. It shows that gossypol inhibited the enzyme activity (greater than 5 micron) and expressed the hemolysis (greater than 50 micron) in vitro in a concentration-dependent manner, and increased the K+-efflux of the cells (10-40 micron). The above effects are antagonized by 1-2% bovine serum albumin. The data demonstrate that gossypol is a specific and potent membrane active agent. These results may be relevant to the in vivo actions of gossypol.

Auditory function in sickle cell anemia

Auditory acuity and central auditory processing were assessed in 22 patients with sickle cell anemia, 13 of whom were chronically transfused, and compared with a control black population. Pure tone air conduction thresholds were within normal limits for all patients, and mean Speech Reception Threshold for each ear was normal at 10 dB. All subjects exhibited type A tympanograms. Central auditory processing was assessed by the Competing Sentence Test and Binaural Fusion Test. No significant differences were found among transfused, nontransfused, and control patients. Abnormal auditory function does not appear to be a common problem in patients with sickle cell disease.

Fused cells of frog proximal tubule: I. Basic membrane properties

Proximal tubular cells of the frog (Rana esculenta) kidney were fused within an isolated tubule portion to giant cells according to the polyethylene-glycol fusion method. Cell membrane potentials (Vm) were measured while cells were superfused with various experimental solutions. Rapid concentration step-changes of different ions allowed to calculate the respective transference numbers (tion). In some experiments the specific cell membrane resistances (Rm) were evaluated by measuring Vm induced by short current pulses injected into the cell with a second electrode. The experiments reveal: i) Fused cells of the proximal tubule exhibit a Vm of -49.5 +/- 1.6 mV (n = 65). ii) Addition of glucose to the perfusate yields a transient depolarization, consistent with a rheogenic Na/glucose cotransport system. iii) In absence of organic substrates the whole cell membrane conductance is made up of K+ and HCO3-. iv) There is a positive relationship between Vm and tK+ and a negative relationship between Vm and tHCO3-. v) HCO3--induced Vm changes are attenuated or abolished when Na+ is replaced with choline+, consistent with a rheogenic Na+/HCO3- cotransport system. vi) Replacement of Na+ by choline+ depolarizes Vm and increases Rm by about 50%; addition of 3 mmol/liter Ba2+ to the Na+-free perfusate increases Rm by about 58% compared to the initial control value. vii) There is no measurable cell membrane Cl- conductance. We conclude that fused cells of proximal tubule exert both luminal and peritubular membrane properties. In absence of organic substrates the cell membrane potential is determined by the HCO3- and K+ transport systems.

[3H]AF-DX 116 labels subsets of muscarinic cholinergic receptors in rat brain and heart

The in vitro binding properties of the novel muscarinic antagonist [3H]AF-DX 116 were studied using a rapid filtration technique. Association and dissociation rates of [3H]AF-DX 116 binding were rapid at 25 degrees C (2.74 and 2.70 X 10(7) min-1 M-1 for K+1; 0.87 and 0.93 min-1 for k-1) but 20-40 times slower at 0-4 degrees C (0.13 and 0.096 X 10(7) min-1 M-1 for k+1; 0.031 and 0.022 min-1 for k-1 in cerebral cortical and cardiac membranes, respectively). Kinetic dissociation constants (Kds) were estimated to be 31.8 nM and 30.9 nM at 25 degrees C; 23.1 nM and 0-4 degrees C for the cerebral cortex and heart, respectively. In saturation studies, [3H]AF-DX 116 labeled 29 percent of the total [3H](-)QNB binding sites in the cerebral cortical membranes and 87 percent in the cardiac membranes, with Kd values of 28.9 nM and 17.9 nM, respectively. Muscarinic antagonists inhibited [3H]AF-DX 116 binding in a rank order of potency of atropine greater than dexetimide greater than AF-DX 116 greater than PZ greater than levetimide in both tissues. Except for PZ/[3H]AF-DX 116 and AF-DX 116/[3H]AF-DX 116 in the cerebral cortex, all the antagonist competition curves had Hill coefficients close to one. Carbachol and oxotremorine produced shallow inhibition curves against [3H]AF-DX 116 binding in both tissues. Regional distribution studies with [3H](-)QNB, [3H]PZ and [3H]AF-DX 116 showed that most of the muscarinic receptors in the cerebral cortex, hippocampus, nucleus accumbens and corpus striatum are of the M1 subtype while those in the brainstem, cerebellum and other lower brain regions are of the M2 subtype. These results indicate that [3H]AF-DX 116 is a useful probe for the study of heterogeneity of muscarinic cholinergic receptors.

Cell membrane potential: a signal to control intracellular pH and transepithelial hydrogen ion secretion in frog kidney

The dependence of intracellular pH (pHi) and transepithelial H+ secretion on the cell membrane potential (Vm) was tested applying pH-sensitive and conventional microelectrodes in giant cells fused from single epithelial cells of the diluting segment and in intact tubules of the frog kidney. An increase of extracellular K+ concentration from 3 to 15 mmol/l decreased Vm from -49 +/- 4 to -29 +/- 1 mV while pHi increased from 7.44 +/- 0.04 to 7.61 +/- 0.06. Addition of 1 mmol/l Ba2+ depolarized Vm from -45 +/- 3 to -32 +/- 2 mV, paralleled by an increase of pHi from 7.46 +/- 0.04 to 7.58 +/- 0.03. Application of 0.05 mmol/l furosemide hyperpolarized Vm from -48 +/- 3 to -53 +/- 3 mV and decreased pHi from 7.47 +/- 0.05 to 7.42 +/- 0.05. In the intact diluting segment of the isolated-perfused frog kidney an increase of peritubular K+ concentration from 3 to 15 mmol/l increased the luminal pH from 7.23 +/- 0.08 to 7.41 +/- 0.08. Addition of Ba2+ to the peritubular perfusate also increased luminal pH from 7.35 +/- 0.07 to 7.46 +/- 0.07. Addition of furosemide decreased luminal pH from 7.32 +/- 0.03 to 7.24 +/- 0.05. We conclude: cell depolarization reduces the driving force for the rheogenic HCO3- exit step across the basolateral cell membrane. HCO3- accumulates in the cytoplasm and pHi increases. An alkaline pHi inactivates the luminal Na+/H+ exchanger. This diminishes transepithelial H+ secretion. Cell hyperpolarization leads to the opposite phenomenon. Thus, pHi serves as signal transducer between cell voltage and Na+/H+ exchange.

A parallel architecture for discrete relaxation algorithm

Discrete relaxation techniques have proven useful in solving a wide range of problems in digital signal and digital image processing, artificial intelligence, operations research, and machine vision. Much work has been devoted to finding efficient hardware architectures. This paper shows that a conventional hardware design for a Discrete Relaxation Algorithm (DRA) suffers from O(n2m3) time complexity and O(n2m2) space complexity. By reformulating DRA into a parallel computational tree and using a multiple tree-root pipelining scheme, time complexity is reduced to O(nm), while the space complexity is reduced by a factor of 2. For certain relaxation processing, the space complexity can even be decreased to O(nm). Furthermore, a technique for dynamic configuring an architectural wavefront is used which leads to an O(n) time highly concurrent DRA3 architecture.

Inhibition of streptomycin-dependent mutation in Escherichia coli on the lytic growth of bacteriophage lambda

Spontaneous streptomycin-dependent mutants (StrDA) were isolated from Escherichia coli C600. On C600 StrD, the lytic growth of phage lambda Nam and lambda cI857 was inhibited. After E. coli lysogenic strain 1.1485 (lambda cI857) mutated to StrDA, induction of lambda was decreased greatly. On StrDA of E. coli strains C600 and 1.1485 (lambda cI857), the plating efficiencies and burst sizes of phage T4 and T7 remained normal. Since StrDA is a mutation in the structural gene for ribosomal protein S12, the results obtained in the present study suggest that ribosomes of the StrDA mutants inhibit the lytic growth of lambda phage. The possibility that StrDA ribosomes inhibit the expression of lambda N gene is discussed based on the comparison of the genetic background of lambda cI857 and lambda Nam.

Aldosterone activates Na+/H+ exchange and raises cytoplasmic pH in target cells of the amphibian kidney

The hypothesis was tested if the mineralocorticoid hormone aldosterone stimulates Na+/H+ exchange in "giant cells" fused from individual target cells of the distal nephron of the frog kidney. By means of microelectrodes, steady-state intracellular pH (pHi) and pHi recovery from an acid load were recorded continuously while the fused cells were exposed to aldosterone. Twenty minutes after addition of the hormone, pHi started to rise and reached a new steady state after about 60 min (delta pHi = 0.28 +/- 0.01). After hormone treatment, pHi recovered significantly faster in response to an intracellular acid load. The diuretic drug amiloride blocked pHi recovery. Experiments in intact tubules showed that aldosterone induces H+ and K+ secretion. Thus, intracellular alkalosis, mediated by Na+/H+ exchange, could serve as a signal that activates pH-sensitive K+ channels of the luminal cell membrane.

Evidence for Na+ dependent rheogenic HCO3- transport in fused cells of frog distal tubules

The mechanism of HCO3- transport was studied applying microelectrodes in "giant" cells fused from single epithelial cells of the diluting segment of frog kidney. A sudden increase of extracellular HCO3- concentration from 10 to 20 mmol/l at constant pH hyperpolarized the cell membrane potential of the fused cell. This cell-voltage response was totally abolished by 10(-3) mol/l SITS and significantly reduced by 10(-4) mol/l acetazolamide or by omission of Na+ from the extracellular perfusate. Removal of Na+ from the perfusate caused a transient depolarization. Reapplication of Na+ induced a transient hyperpolarization. 10(-3) mol/l SITS abolished the cell-voltage response to removal and reapplication of Na+. In the intact diluting segment of the isolated perfused frog kidney peritubular perfusion of 10(-4) mol/l acetazolamide reduced the limiting transepithelial electrochemical gradient for H+ significantly from 30 +/- 4 mV to 14 +/- 3 mV. The results suggest: In the diluting segment of the frog kidney a Na+-dependent rheogenic HCO3- transport system exists across the peritubular cell membrane. This rheogenic peritubular Na+/HCO3- cotransporter cooperates with a Na+/H+ exchanger in the luminal membrane, thus driving HCO3- reabsorption. Reabsorption of HCO3- and secretion of H+ depend upon the presence of carbonic anhydrase.

Childhood monosomy 7 syndrome: clinical and in vitro studies

The clinical and cell growth characteristics of 11 children with monosomy 7 presenting as preleukemia (eight cases) or acute nonlymphoblastic leukemia (three cases) were studied. Anemia was common to all patients, with nine showing leukocytosis, seven thrombocytopenia, and one thrombocytosis. There was a striking predominance of males (M/F ratio, 10:1) and a young median age (3 years). Preleukemia evolved to acute nonlymphoblastic leukemia in five patients and to myelofibrosis in one. In vitro studies of bone marrow progenitor cells cultured in leukocyte feeder-stimulated agar revealed abnormal cell proliferative patterns, most often an increased number of small clusters, for all 11 subjects. The cells of some preleukemic patients showed increased growth even in the absence of an exogenous source of colony-stimulating factor, suggesting autonomous growth or possibly autocrine stimulation. Combination chemotherapy or bone marrow transplantation failed to induce complete remission in the seven patients who were treated. Our findings in these 11 cases confirm the poor prognosis of monosomy 7 presenting as preleukemia in children. The in vitro studies suggest an association between altered cell growth in vitro and clinical evolution to frank leukemia.

Intravenous gamma globulin for thrombocytopenia in children with Evans syndrome

We describe three patients with Evans syndrome (immune hemolytic anemia and immune thrombocytopenia) who were refractory to conventional therapy, including steroids and splenectomy in all of the patients, vincristine in two, and cyclophosphamide in one. The patients were then treated with modified intravenous gamma globulin 0.4 g/kg/day for 5 consecutive days. Two patients failed to respond, but the third had a clinical remission after gamma globulin therapy. Given the usual chronic and relapsing course of Evans syndrome and the poor response to conventional therapy, we recommend that high dose i.v. gamma globulin be considered an alternative therapy in the management of these patients.

Low levels of prostaglandins in human milk after purification by high performance liquid chromatography

In order to validate methodology for quantifying arachidonic acid metabolites in human milk, we measured five prostaglandins (PGs) using radioimmunoassay (RIA): PGE2, PGF2 alpha, thromboxane B2 (TXB2), 6-keto-PGF1 alpha (6KF1 alpha) and 13,14-dihydro-15-keto-PGF2 alpha (DHKF2 alpha). RIA was performed after extraction with C18 Sep-Pak cartridge and/or further purification with reverse-phase high performance liquid chromatography (rp-HPLC). Recovery was monitored throughout the purification steps. Confirming findings of previously reported studies, we found PGE and the PGF2 alpha metabolite, DHKF2 alpha to be the major PGs in extracted human milk. After HPLC purification, however, no predominant PG was found, and the PG levels, especially those of PGE2 and DHKF2 alpha, were considerably lower than levels in the extracted sample. A noteworthy finding was the presence of immunoreactive substances in HPLC fractions not within the area of the PG peak; this suggests that the decreased levels of PGs in human milk measured by RIA after rp-HPLC are due to the elimination of the nonspecific immunoreactive materials present in the sample.