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Biomedical subjects

M Fukuda

Publications and source records attributed to M Fukuda.

At least 307 records · Page 17Linked to original sources
PubMed1999

Association between arthroscopic diagnosis of temporomandibular joint osteoarthritis and synovial fluid nitric oxide levels.

OBJECTIVE: The purpose of this study was to determine whether there is a relationship between synovial fluid levels of nitric oxide and clinical and arthroscopic findings of synovitis or cartilaginous degeneration. STUDY DESIGN: Arthroscopic surgery was performed on 20 joints in 15 female patients with internal derangement and osteoarthritis of the temporomandibular joint. Synovial fluid aspirates were obtained immediately before arthroscopy. Synovial fluid was also obtained from 14 joints of 11 female asymptomatic volunteers. The concentration of nitrite in the fluid recovered from each temporomandibular joint was measured through use of a highly sensitive and specific chemiluminescence detection method, calibrated per 1 mg of synovial fluid protein and expressed as nitric oxide; the result was then compared with clinical and arthroscopic findings of synovitis and cartilaginous degeneration. RESULTS: Significantly higher levels of nitric oxide (median, 0.331 micromol/mg) were seen in the patients with internal derangement and osteoarthritis than in the control group (median, 0.001 micromol/mg; P<.0001). Synovial fluid from joints with pain in the joint area had significantly higher levels of nitric oxide than did fluid from joints without such pain. Synovial fluid from joints with degenerative changes (median, 0.467 micromol/mg) had significantly higher levels of nitric oxide than did fluid from joints without osteoarthritis (median, 0.057 micromol/mg; P<.05). Although the levels of nitric oxide in synovial fluid aspirates were markedly elevated in some joints with synovitis, there was no correlation between the levels of nitric oxide and the presence of synovitis. CONCLUSIONS: The findings indicate that increased levels of nitric oxide are involved in the pathogenesis of cartilaginous degeneration of the temporomandibular joint.

Adult↗
PubMed1999

Nucleotide sequences and characterization of genes encoding naphthalene upper pathway of pseudomonas aeruginosa PaK1 and Pseudomonas putida OUS82.

A 12,808-nucleotide containing DNA fragment cloned from naphthalene-utilizing (Nah+) Pseudomonas aeruginosa PaK1 was analyzed and compared with the genes (pah(OUS)) of a 14,462-nucleotide DNA fragment from Pseudomonas putida OUS82. The DNA sequence analyses demonstrated that the naphthalene upper-pathway genes and their deduced enzymes were very similar between the two bacteria: nucleotide similarities, 83-93%; amino acid similarities, 79-95%. These genes were also similar to those of the nah operon of plasmid NAH7; in particular, the OUS82 genes were similar to the nah genes, whereas the PaK1 genes were almost identical to the dox genes of Pseudomonas sp. C18. A region homologous with the 84-bp repeated sequence that Eaton (J. Bacteriol., 176, 7757-7762, 1994) has found at a site upstream of he nah operon was found only in a region downstream of the pah(PaK) gene cluster in PaK1 and on both sides of the pah(OUS) gene cluster in OUS82. A PaK1 gene, corresponding to an unknown gene (nahQ) in the nah operon, is located between the 1,2-dihydroxynaphthalene dioxygenase gene and the trans-o-hydroxybenzylindenepyruvate (tHBP A) hydratase-aldolase gene (nahE), and was suggested to be involved in the conversion of naphthalene to salicylate. Just downstream of the pah(PaK) gene cluster, a portion of a region was identical to one-third of the transposase gene (tnpA) in a phenol-catabolic plasmid pEST1226.

Journal Article↗
PubMed1999

Synthesis of selectively radiolabeled hexasaccharides for the determination of enzymatic regioselectivity.

Poly-N-acetyllactosamines provide backbone structures for functional modifications such as sialyl Lewis X. To understand how the biosynthesis of poly-N-acetyllactosamines is regulated, two branched oligosaccharides of the structure Galbeta1,4GlcNAcbeta1, 6(Galbeta1,4GlcNAcbeta1,2)-Manalpha1,6Manbeta-octyl 1 and 2 were synthesized in which one of the terminal galactose units was selectively radiolabeled. Hexasaccharides 1 and 2 were assembled from the chemically synthesized pentasaccharide precursors GlcNAcbeta1,6(Galbeta1,4GlcNAcbeta1,2)-Manalpha1,6Manbeta-octyl3 and Galbeta1,4GlcNAcbeta1,6(GlcNAcbeta1,2) - Manalpha1,6 Manbeta-octyl 4 respectively, through treatment with UDP-1-[3H]-Gal and beta1,4 galactosyltransferase. Compounds 1 and 2 were subsequently incubated with UDP-GlcNAc and the UDP-GlcNAc: Galbeta1-4Glc(NAc) beta1,3-N-acetylglucosaminyltransferase (i-GlcNAc transferase) resulting in a partial conversion to a mixture of heptasaccharides which were purified by HPLC. The branch selectivity of the addition of N-acetylglucosamine to compounds 1 and 2 was then characterized by endo-beta-galactosidase digestion of the heptasaccharides, followed by isolation of the resultant pentasaccharides on C18 reverse-phase silica cartridges. Comparison of the amount of radiolabel to a control reaction lacking endo-beta-galactosidase indicated the favored site of GlcNAc addition to be the lower beta1,2-branch over the beta1,6 branch by a 3 :1 ratio.

Binding Sites↗
PubMed1999

Degradation of anaerobic reductive dechlorination products of Aroclor 1242 by four aerobic bacteria.

We studied the aerobic degradation of eight PCB congeners which comprise from 70 to 85% of the anaerobic dechlorination products from Aroclor 1242, including 2-, 4-, 2,4-, 2,6-, 2,2'-, 2,4'-, 2,2', 4-, and 2,4,4'-chlorobiphenyl (CB), and the biodegradation of their mixtures designed to simulate anaerobic dechlorination profiles M and C. Strains Comamonas testosteroni VP44 and Rhodococcus erythreus NY05 preferentially oxidized a para-substituted ring, while Rhodococcus sp. RHA1, similar to well known strain Burkholderia sp. LB400, preferably attacked an ortho-chlorinated ring. Strains with ortho-directed attack extensively degraded 2,4'- and 2,4,4'-CB into 4-chlorobenzoate, while bacteria with para-directed attack transformed these congeners mostly into potentially problematic meta-cleavage products. The strains that preferentially oxidized an ortho-substituted ring readily degraded seven of the eight congeners supplied individually; only 2,6-CB was poorly degraded. Degradation of 2,2'- and 2,4,4'-CB was reduced when present in mixtures M and C. Higher efficiencies of degradation of the individual congeners and defined PCB mixtures M and C and greater production of chlorobenzoates were observed with bacteria that preferentially attack an ortho-substituted ring. PCB congeners 2,4'-, 2,2',4-, and 2,4,4'-CB can be used to easily identify bacteria with ortho-directed attack which are advantageous for use in the aerobic stage of the two-phase (anaerobic/aerobic) PCB bioremediation scheme.

Anaerobiosis↗
PubMed1999

Bioavailability of dried asakusanori (porphyra tenera) as a source of Cobalamin (Vitamin B12).

We have already reported that raw nori (Porphyra tenera) contains cobalamin (Cbl) but not Cbl analogues (J. Nutr. Sci. Vitaminol., 42, 497, 1996). It seems, therefore, that it is an excellent natural vegetable source of Cbl. On the other hand, it has been reported that the Cbl nutritional status of vegetarian children deteriorated as estimated by the hematological index, mean corpuscular volume (MCV), after they had dried nori as a source of Cbl. Such a discrepancy between raw and dried nori as a source of Cbl led us to investigate whether Cbl in dried nori had different properties from that in raw nori. We found that contents of Cbl homologues determined by a bioassay method in both raw and dried nori were similar. The urinary methylmalonic acid excretion increased when human female volunteers were given 40 g of dried nori daily during the test period. On the other hand, the urinary methylmalonic acid excretion did not change when volunteers were daily given 320 g of raw nori, which was equivalent to 40 g of the dried one on the basis of dehydrated weight, during the test period. By paper chromatography, 65% of the Cbl homologues were found to be comprised of Cbl analogues in dried nori, while 73% of the Cbl homologues in the raw nori were genuine Cbl. These results were confirmed by the finding that the bioassay method gave higher values for Cbl homologues than those obtained by a competitive binding assay method using an intrinsic factor as a Cbl-binding protein. Our present data demonstrated that Cbl in raw nori can be changed into harmful Cbl analogues by the drying process.

Adult↗
PubMed1999

Characterization of Sphingomonas paucimobilis SYK-6 genes involved in degradation of lignin-related compounds.

Sphingomonas paucimobilis SYK-6 is able to grow on a wide variety of dimeric lignin compounds. These compounds are degraded via vanillate and syringate by a unique enzymatic system, composed of etherases, O demethylases, ring cleavage oxygenases and side chain cleaving enzymes. These unique and specific lignin modification enzymes are thought to be powerful tools for utilization of the most abundant aromatic biomass, lignin. Here, we focus on the genes and enzymes involved in beta-aryl ether cleavage and biphenyl degradation. Two unique etherases are involved in the reductive cleavage of beta-aryl ether. These two etherases have amino acid sequence similarity with the glutathione S-transferases, and use glutathione as a hydrogen donor. It was found that 5,5'-dehydrodivanillate, which is a typical lignin-related biphenyl structure, was transformed into 5-carboxyvanillate by the reaction sequence of O-demethylation, meta-ring cleavage, and hydrolysis, and the genes involved in the latter two reactions have been characterized. Vanillate and syringate are the most common intermediate metabolites in lignin catabolism. These compounds are initially O-demethylated and the resulting diol compounds, protocatechuate (PCA) and 3-O-methylgallate, respectively, are subjected to ring cleavage catalyzed by PCA 4,5-dioxygenase. The ring cleavage products generated are further degraded through the PCA 4,5-cleavage pathway. We have isolated and characterized genes for enzymes involved in this pathway. Disruption of a gene for 2-pyrone-4,6-dicarboxylate hydrolase (ligI) in this pathway suggested that an alternative route for 3-O-methylgallate degradation, in which ligI is not involved, would play a role in syringate catabolism. In this article, we describe the genetic and biochemical features of the S. paucimobilis SYK-6 genes involved in degradation of lignin-related compounds. A possible application of the SYK-6 lignin degradation system to produce a valuable chemical material is also described.

Journal Article↗
PubMed1999

Heat shock protein 70 (hsp70) as a major target of the antibody response in patients with pulmonary cryptococcosis.

Cryptococcus neoformans causes infection in individuals with defective T cell function, such as AIDS, as well as without underlying disease. It has been suggested that humoral as well as cellular immunity might play an important role in the immune response to C. neoformans infection. We have recently shown, using immunoblotting, that the 70-kD hsp family of C. neoformans was the major target molecule of the humoral response in murine pulmonary cryptococcosis. In this study we also used immunoblotting to define the antibody responses in the sera of 24 patients with pulmonary cryptococcosis: 21 proven and three suspected diagnoses. Anti-C. neoformans hsp70 antibody was detected in 16 of 24 (66.7%) patients with pulmonary cryptococcosis. Fourteen of 17 (82.3%) patients with high antigen titres (> or = 1:8) and two of seven (28.6%) patients with low titres (< or = 1:4) had detectable levels of anti-hsp70 antibody. Sera from patients positive for anti-hsp70 antibody showed high titres in the Eiken latex agglutination test for the detection of serum cryptococcal antigen. Our results indicate that the 70-kD hsp family from C. neoformans appears to be a major target molecule of the humoral response, not only in murine pulmonary cryptococcosis, but also in human patients with pulmonary cryptococcosis.

Adult↗
PubMed1999

Rapid intestinal ischaemia-reperfusion injury is suppressed in genetically mast cell-deficient Ws/Ws rats.

Ws/Ws rats have a small deletion of the c-kit gene, and are deficient in both mucosal and connective tissue-type mast cells. In this study, the role of mucosal type mast cells (MMC) in the development of intestinal ischaemia-reperfusion injury was investigated in Ws/Ws rats. Autoperfused segments of the jejunum were exposed to 60 min of ischaemia, followed by reperfusion for various time periods. The epithelial permeability was then assessed by the 51Cr-EDTA clearance rate. In the control (+/+) rats, the maximal increase in mucosal permeability was achieved at 45 min of reperfusion. In contrast, this increase was significantly and potently attenuated in the Ws/Ws rats. Mucosal alkaline phosphatase activity decreased in the control (+/+) rats, but was not altered in the Ws/Ws rats. There were no differences in mucosal myeloperoxidase activity, indicating that granulocytes did not contribute to tissue injury. These results provide direct evidence for the role of mast cells in the pathogenesis of intestinal ischaemia-reperfusion injury.

Animals↗
PubMed1999

Involvement of CRM1, a nuclear export receptor, in mRNA export in mammalian cells and fission yeast.

BACKGROUND: CRM1, an evolutionarily conserved protein, was shown to be a receptor for leucine-rich nuclear export signal (NES)-dependent protein transport. In lower eukaryotes CRM1 is reported to be required for the export of mRNA, however, involvement of the NES-dependent transport pathway in mRNA export in higher eukaryotes has not been established. RESULTS: We have found that treatment of mammalian cells with leptomycin B (LMB), a specific inhibitor of CRM1, induces the nuclear accumulation of endogenous mRNA, probably due to the inhibition of its export. In fission yeasts, the nuclear accumulation of mRNA also occurred in cells treated with LMB or in a temperature-sensitive crm1 mutant at a restrictive temperature. A synthetic mRNA that was injected into the nucleus of mammalian cultured cells was exported from the nucleus within 5 h. This export was inhibited by both wheat germ agglutinin and a temperature of 4 degrees C. Importantly, this mRNA export was inhibited by LMB or by an excess amount of the NES peptide-conjugates. LMB treatment, on the other hand, rapidly induced the nuclear entry of RanBP1, a factor involved in the active nucleocytoplasmic transport, although the treatment did not interfere with a nuclear localization signal-dependent transport system within 7 h. CONCLUSION: These results suggest that CRM1 is involved in mRNA export in eukaryotic cells.

Animals↗
PubMed1999

A search for a mutation in the tumour necrosis factor-alpha gene in narcolepsy.

The discovery of almost 100% association of narcolepsy with human leukocyte antigens (HLA) DR2 antigen prompted molecular biological research of this disorder. In the HLA class II gene cluster, the gene for tumour necrosis factor-alpha (TNF-alpha), which plays a role in the regulation of normal human sleep, is located. The present study searched for a mutation in the TNF-alpha gene by single-strand conformation polymorphism analysis (SSCP) in patients with narcolepsy. No mutation was detected in exons and introns of the TNF-alpha gene by SSCP and sequencing.

DNA Mutational Analysis↗
PubMed1999

Response of skin blood volume, velocity and flow to local warming in newborns, measured by laser Doppler flowmetry.

BACKGROUND: In order to know the response of the skin microcirculation to local warming, we determined changes in the skin blood volume (Vol), velocity (Vel) and flow (F) by using a new laser Doppler device on newborns. METHODS: The study subjects were 39 infants whose gestational age was 34.1 +/- 2.8 weeks and birth weight was 2189 +/- 572 g. The study was performed from 8 h postnatally to 28 postnatal days. We measured skin blood volume, velocity and flow at 36 degrees C (Vol36, Vel36, F36), and each value at 5 min (Vol44-5, Vel44-5, F44-5) and 10 min (Vol44-10, Vel44-10, F44-10) after local warming was applied at 44 degrees C and the response curve of each parameter was obtained. Subsequently, serial changes in the response of skin microcirculation to local warming were investigated in nine very low birth weight (VLBW) infants (28.3 +/- 0.9 weeks, 1150 +/- 148 g) and 12 low birth weight (LBW) infants (32.8 +/- 1.3 weeks, 1971 +/- 292 g). The F36, the increment rate of blood volume (delta Vol) and the increment rate of blood velocity (delta Vel) were obtained within 24 h, from day 1 to day 7 and from day 8 to day 30 in both VLBW and LBW infants and from day 31 to day 60 and at more than 61 days in VLBW infants. The F36, delta Vol and delta Vel were compared during the study periods in VLBW and LBW infants. All results were expressed as mean +/- SD. RESULTS: The results showed that F36/F44-10 and F44-5/F44-10, Vol36/Vol44-10 and Vol44-5/Vol44-10, Vel36/Vel44-10 and Vel44-5/Vel44-10 were 0.25 +/- 0.09 and 0.74 +/- 0.17, 0.58 +/- 0.14 and 0.94 +/- 0.08, 0.42 +/- 0.12 and 0.79 +/- 0.15, respectively. Different modes of delivery did not have a significant effect on this response. The F36 in VLBW infants was high during the early neonatal period and gradually decreased with postnatal age. The delta Vol was low in VLBW infants during the neonatal period and gradually increased. The F36 in VLBW1-7 was significantly higher than in LBW1-7 (P < 0.01) and full-term controls (P < 0.001). The delta Vol in VLBW1-7 was 0.26 +/- 0.23, which is significantly lower than in LBW1-7 (0.57 +/- 0.17, P < 0.001) and full-term controls (0.77 +/- 0.21, P < 0.001). The delta Vel in VLBW1-7 and LBW1-7 was significantly higher than in controls (P < 0.05). CONCLUSIONS: The skin blood flow increased continuously when local warming was applied at 44 degrees C. This high blood flow and limited potential of vasodilatation are the characteristics of the skin microcirculation in VLBW infants during the neonatal period.

Blood Flow Velocity↗
PubMed1999

Acetylcholine suppresses the spread of excitation in the visual cortex revealed by optical recording: possible differential effect depending on the source of input.

Optical recording with a voltage-sensitive dye was performed in visual cortical slices of the rat to determine the effect of acetylcholine (ACh) on the spread of excitation. In the presence of ACh, the spread of excitation initiated by stimulation at the white matter/layer VI (WM/VI) was greatly suppressed throughout the cortex, with less suppression in the middle layers. By comparing the effect of ACh with that of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), the fraction of the synaptic component that was sensitive to ACh was evaluated. ACh suppressed approximately 40-50% (maximum 55.8%, n = 11) of the initial synaptic component in the superficial and deep layers. In the middle, however, the effect was weakest and only approximately 20-30% (minimum 20.9%, n = 11) of the initial synaptic component was suppressed. On the basis of histological analysis, the region with the weakest ACh effect extended from upper V to lower II/III. To identify the site of ACh action in terms of pre- versus postsynaptic localization, exogenous glutamate was applied. Because ACh did not suppress the excitation induced by glutamate, the site of the ACh action was indicated to be presynaptic. When layer II/III was stimulated instead of WM/VI, the suppression was uniform throughout the cortex. A muscarinic receptor antagonist, atropine, blocked the suppression by ACh. In conclusion, our results indicate the following two points. First, ACh strongly suppresses intracortical connectivity through presynaptic muscarinic receptors. Secondly, in contrast to the intracortical connection, some group(s) of fibres, possibly thalamocortical afferents that arise from white matter and terminate in the middle cortical layers are suppressed much less by ACh. While ACh has been reported to have confusingly diverse effects, e.g. direct depolarization and hyperpolarization as well as synaptic facilitation and suppression, its effect on the propagation of excitation is very clear; suppression on intracortical connection, leaving thalamocortical inputs rather intact. We postulate that cholinergic innervation enables the afferent input to have a relatively dominant effect in the cortex.

Acetylcholine↗
PubMed1999

Association of plasma fibrinogen level and blood pressure with diabetic retinopathy, and renal complications associated with proliferative diabetic retinopathy, in Type 2 diabetes mellitus.

AIM: To clarify the association of several clinical parameters, including plasma fibrinogen level, with diabetic retinopathy in patients with Type 2 diabetes mellitus (DM). METHODS: A total of 294 Japanese patients with Type 2DM were studied; 53 patients with no diabetic retinopathy (NDR), 90 with background diabetic retinopathy (BDR), and 151 with proliferative diabetic retinopathy (PDR). Multiple logistic regression analysis was performed to assess variables independently associated with diabetic retinopathy in two settings: presence of retinopathy of any severity and presence of advanced retinopathy. RESULTS: The following parameters were identified as independent factors associated with the presence of diabetic retinopathy (NDR vs. BDR + PDR): type of therapy (P<0.0005), log-transformed plasma fibrinogen level (P < 0.05), mean blood pressure (P < 0.05), and duration of diabetes (P < 0.05). The independent variables associated with advanced retinopathy were type of therapy (P<0.00005), age (P<0.0005) and nephropathy (P<0.05). Body mass index, smoking and hypertensive status, HbA1c and total cholesterol levels were not independently associated. CONCLUSIONS: These data suggest that in patients with Type 2 DM, an increased blood viscosity due to high fibrinogen level as well as an elevated intravessel pressure play a role in the development of diabetic retinopathy, and that the progression to PDR is influenced or accompanied by the deterioration of renal status.

Aged↗
PubMed1999

Length rather than a specific allele of dinucleotide repeat in the 5' upstream region of the aldose reductase gene is associated with diabetic retinopathy.

AIMS: To assess the possible contribution of a genetic factor to diabetic retinopathy. METHODS: (CA)n repeat length was investigated in the 5' upstream region of the gene coding for aldose reductase (AR), which is a key enzyme of the polyol pathway and plays a role in hyperglycaemia-induced tissue damage, in Japanese patients with Type 2 DM. RESULTS: The dinucleotide repeat length was significantly associated with proliferative diabetic retinopathy (PDR) (P= 0.029, Mann-Whitney U-test); i.e. shorter alleles were more prevalent in the PDR group than in the control group. CONCLUSIONS: (CA)n repeat length, rather than a specific allele, in the 5' upstream region of the AR gene is associated with diabetic retinopathy. These data suggest that the AR locus plays a role in genetic susceptibility to diabetic retinopathy and that dinucleotide repeats in genomic DNA may be related to disease predisposition.

Aged↗
PubMed1999

Effect of an aluminum hydroxide-magnesium hydroxide combination drug on adhesion, IL-8 inducibility, and expression of HSP60 by Helicobacter pylori.

BACKGROUND: Co-magaldrox (Maalox) is used world-wide as an antacid and as a cytoprotective agent for gastritis and peptic ulcer diseases. We examined the effects of co-magaldrox on Helicobacter pylori. METHODS: Adhesion of H. pylori to human gastric epithelial cells (MKN45) was evaluated by flow cytometry. Morphologic changes in H. pylori caused by co-magaldrox were determined by scanning electron microscopy. Induction of interleukin-8 (IL-8) from MKN45 cells was examined with enzyme-linked immunosorbent assay, and the intracellular and extracellular expression of heat-shock protein 60 (HSP60) was analyzed with sodium dodecyl sulphate-polyacrylamide gel electrophoresis and flow cytometry. RESULTS: Adhesion of H. pylori to MKN 45 cells was significantly inhibited by 1.25%-5% comagaldrox. H. pylori aggregated with co-magaldrox according to an electron microscopic examination. IL-8 secretion from MKN45 cells after H. pylori infection was also inhibited by co-magaldrox. Extracellular expression of HSP60 on the surface of H. pylori was decreased after treatment with comagaldrox, whereas the intracellular synthesis of HSP60 was not. HSP60-induced IL-8 secretion was significantly inhibited by co-magaldrox in a dose-dependent manner. CONCLUSIONS: These results show that co-magaldrox suppressed the expression of the following virulence factors: adhesion, IL-8 inducibility, and expression of extracellular HSP60. Therefore, co-magaldrox is a potent anti-H. pylori and cytoprotective drug.

Aluminum Hydroxide↗
PubMed1999

Rabbit syndrome following phenol ingestion.

CASE REPORT: An elderly Japanese woman ingested a massive quantity of phenol in a suicide attempt. She was admitted to the Emergency Department in respiratory arrest and deep coma. Duodenogastritis was evident endoscopically. With the return of spontaneous respiration and consciousness, fine, rapid rhythmic perioral movements developed together with Parkinsonian findings. The abnormal movements were aggravated by administration of a neuroleptic and ameliorated by discontinuing the drug; they disappeared completely by hospital day 15. In addition to neuroleptic drugs, phenol intoxication may cause the rabbit syndrome by inducing cholinergic dominance with relative dopamine hypofunction in the central nervous system.

Aged↗
PubMed1999

Anovulations in an ovary during two menstrual cycles enhance the pregnancy potential of oocytes matured in that ovary during the following third cycle.

The aim of this study was to test whether ovulation from an ovary affects the health of oocytes from dominant follicles in that ovary two cycles later. A total of 80 women each with two intact ovaries underwent 270 treatment cycles (155 natural cycles and 115 clomiphene citrate cycles) all showing unilateral ovulation. The results from the in-vitro fertilization (IVF) treatment were grouped according to whether ovulation (O) or anovulation (A) (no ovulation) was observed in the ovary with dominant follicle during the treatment cycle in the previous two cycles: O-O, A-O, O-A and A-A (previous second cycle-previous first cycle). The rate of pre-embryo formation in A-A was significantly higher than that of O-A. The pregnancy rate in A-A (29%) was also higher than those of O-A (13%), A-O (9%) and O-O (5%). These rates increased from O-O to A-A as the number of previous ovulations in an ovary decreased. The presence of a corpus luteum and/or a dominant follicle is likely to exert local negative effects on the health of the oocyte contained in the follicle selected to ovulate up to two cycles later. Anovulations in an ovary for two menstrual cycles may therefore provide improved conditions for the development of a healthier oocyte with an increased pregnancy potential.

Adult↗