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Biomedical subjects

A Simon

Publications and source records attributed to A Simon.

At least 217 records · Page 12Linked to original sources
PubMed1996

Echographic assessment of carotid and femoral arterial structure in men with essential hypertension. Group PCVMETRA.

Extracoronary in vivo structural arterial changes were studied in asymptomatic essential hypertension. Carotid and femoral arteries were examined with B-mode echography for the presence or absence of plaque (the whole vascular segments of each vessel in the both sides) and for automated measurement of the far wall intima-media thickness (the vascular segment of each vessel proximal to the bifurcation in the right side) in 53 never treated hypertensive men and 133 normotensive men similar with regard to age, serum cholesterol levels, and smoking history. In the hypertensive group carotid plaque was more frequent (P < .05) and carotid and femoral intima-media thicknesses were greater (P < .001) than in the normotensive group. In the overall normotensive and hypertensive population intima-media thickness was independently associated with age and systolic pressure in both arteries (P < .001) and with cholesterol in the femoral artery (P < .05) while plaque was associated with systolic pressure (P < .01), and cholesterol (P < .01) in the carotid arteries and with age (P < .01), cholesterol (P < .05), and smoking (P < .001) in the femoral arteries. No significant difference in intima-media thickness in both arteries existed between hypertensive subjects with plaque and those without. Wall thickening and plaque were more frequent in hypertensive patients. Thickening was distributed homogeneously to both arteries, while plaque affected preferentially the femoral bed. The influence of age and pressure was more marked on intima-media thickness than on plaque. The lack of association between wall thickening and plaque suggested that vascular hypertrophy and early atherosis might be two different structural changes.

Adult↗
PubMed1996

Endometrial preparation: lessons from oocyte donation.

OBJECTIVE: To gain insight into the physiology of human endometrial development after artificial preparation with estrogen (E) and P, before oocyte donation. DESIGN: Review and analysis of relevant studies published in the last decade, identified through the literature and Medline searches. RESULTS: Oocyte donation represents a unique in vivo experimental model in the human that permits the study of endometrial development under controlled variable conditions. Early studies have shown that adequate endometrial preparation can be achieved by sequential E and P only. The successful implementation of the simplified approach to oocyte donation demonstrated that satisfactory endometrial receptivity is not dependent on incremental administration of E and P and similarly can be achieved by fixed dosages of these steroids. Moreover, numerous clinical oocyte donation studies have shown that both physiologic and supraphysiologic levels of E and P have resulted in good endometrial development and pregnancy rates, underlining the relative insensitivity of the endometrium to extreme hormonal conditions. In addition, it has been clarified that the endometrium is tolerant of some manipulations during the follicular phase. Contrary to morphological studies that demonstrated preservation of endometrial preparation after luteal E depletion, preliminary evidence suggests that the functional capacity of the endometrium could be affected adversely. CONCLUSION: In contrast to early oocyte donation studies, which indicated a correlation between morphologic integrity and functional capacity of the endometrium, some evidence presented in this review demonstrates that adequate endometrial morphology does not always imply normal endometrial receptivity.

Endometrium↗
PubMed1996

Cholesterol lowering therapy inhibits the low-flow mediated vasoconstriction of the brachial artery in hypercholesterolaemic subjects.

1. We tested whether lipid lowering treatment with HMG CoA reductase inhibitor modified the flow mediated large artery reactivity in primary pure hypercholesterolaemia. 2. Abnormalities in arterial reactivity have been described in the presence of high blood cholesterol, in particular an enhanced constriction of the brachial artery in response to acute induction of a low flow state. 3. Using pulsed-Doppler, we measured brachial artery diameter and flow velocity at rest and their changes induced by wrist occlusion before and after 3 months of double-blind treatment by pravastatin (40 mg orally) in 13 subjects and placebo in 15 others. 4. The significant decrease (P < 0.01) in diameter induced by wrist occlusion before (0.34 +/- 0.08 mm) placebo and pravastatin (0.39 +/- 0.10 mm) persisted after placebo (0.26 +/- 0.07 mm) but was abolished after pravastatin (0.07 +/- 0.05 mm). The absolute change in diameter induced by wrist occlusion was lower after than before pravastatin (P < 0.01) and lower after pravastin than after placebo (P < 0.05). Diameter during the wrist occlusion was higher after pravastatin than after placebo (4.35 +/- 0.16 vs 3.89 +/- 0.09 mm); P < 0.01). 5. These findings indicate that the lipid changes induced by pravastatin and/or some unknown but direct mechanism of the drug itself inhibit low-flow-mediated vasoconstriction associated with hypercholesterolaemia. Such effects may have important implications for the treatment of vasospasm often seen in the presence of high blood cholesterol.

Adult↗
PubMed1996

Dopamine inhibits melatonin synthesis in photoreceptor cells through a D2-like receptor subtype in the rat retina: biochemical and histochemical evidence.

An intrinsic oscillator, using dopamine and melatonin as antagonist signals, controls rhythmic events in the retina of nonmammals. The purpose of the present work was to localize and characterize a dopamine receptor responsible for the nocturnal inhibition of melatonin synthesis in photoreceptor cells in a mammalian retina. An antibody against the D2 receptor stained photoreceptor cell inner segments of the rat retina. alpha-Methyl-p-tyrosine, a competitive inhibitor of tyrosine hydroxylase, enhanced the nocturnal content of melatonin, suggesting the dopamine control of melatonin synthesis as in non-mammals. Clozapine, a D2c/D4 antagonist, also enhanced the nocturnal level of melatonin, whereas raclopride, a D2A antagonist, did not. Taken together, these results support the control of melatonin levels by dopamine through a D2C/D4 receptor in photoreceptor cells of the rat retina. The presence of D4 receptors in the rat retina was confirmed by reverse transcription-PCR.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1996

[Glycerol as a feed ingredient for broiler chickens].

In a first trial glycerol was tested as a feed ingredient for broiler chickens. The influence of glycerol supplementation on weight gain, feed intake, feed conversion ratio and N-balance was proved. 90 Broiler chickens (Lohmann Meat) were fed ad libitum in 6 groups with nearly isoenergetic diets based on corn and soybean meal with 23% crude protein and 0; 5; 10; 15; 20 or 25% pure glycerol in the DM. During a feeding period of 31 days animals had have a very good intake of all experimental diets. The highest weight gains were observed in the groups with 5 and 10% glycerol (34.9 and 35.3 g/animal.d, resp.). However, this effect was not significant compared to the control group (34.3 g/animal.d), but was significant superior to the gain of groups with 20 and 25% glycerol in the diet (30.2 and 26.6 g/animal.d, resp.). The feed conversion ratio was unchanged up to 10% glycerol (1.65 kg/kg gain) and rose to 2.08 kg/kg gain with 25% glycerol. Up to 20% glycerol the N-balance (1.6 to 1.8 g N/animal.d) was positively correlated with the glycerol content in the diet (r = 0.98). The estimation of the plasma glycerol level 2 hours after feeding indicated a remarkable increase already with a 5% supplementation of glycerol from 0.65 (control) to 4.36 mmol/l. Further supplementation caused on average 11 to 54 mmol glycerol/l varying considerably between the individual animals. In general 25% glycerol in the diet caused the lowest performance and pathological changes in the crop epithelium, liver and kidneys. From the point of view of weight gain, feed intake, and feed conversion ratio as well as N-balance a supplementation of 5 to 10% glycerol seems to be beneficial.

Animal Feed↗
PubMed1996

In vitro susceptibilities of 180 clinical isolates of Haemophilus influenzae to ampicillin, amoxycillin/clavulanate, cefaclor, cefuroxime, cefotaxime, clarithromycin, and azithromycin.

One hundred eighty consecutive, unduplicate isolates of Haemophilus influenzae from clinical specimens collected from November 1994 through February 1995 in nine general hospitals throughout Belgium were examined for beta-lactamase production using a nitrocefin-based test, and for their in vitro susceptibilities to ampicillin, amoxycillin/clavulanate, cefaclor, cefuroxime, cefotaxime, clarithromycin and azithromycin by means of the NCCLS agar dilution test. The isolates were all from respiratory tract specimens. The prevalence of capsular type b was 1.1%, and the overall rate of beta-lactamase production 16.7%. Rates of beta-lactamase production were higher in isolates from children (22.0%) than in those from adults (15.3%), and in isolates from upper respiratory tract specimens (22.0%) than in those from the lower respiratory tract (15.1%). Beta-lactamase-negative ampicillin resistance amounted to 1.1%. Cefotaxime had the highest activity on a weight basis [MIC (minimal inhibitory concentration) for 50% of the isolates tested (MIC50) < or = 0.06 microgram/ml], followed by ampicillin (MIC50 of 0.25 microgram/ml), amoxycillin/clavulanate and cefuroxime (MIC50 of 0.5 microgram/ml), azithromycin (MIC50 of 2 micrograms/ml), cefaclor (MIC50 of 4 micrograms/ml), and clarithromycin (MIC50 of 8 micrograms/ml). Cefotaxime was also the most active drug in terms of susceptibility rates of the isolates (100.0%), followed by amoxycillin/clavulanate and azithromycin (98.9%), cefuroxime (97.2%), cefaclor (89.4%), clarithromycin (82.8%), and ampicillin (82.2%). In conclusion, amoxycillin/clavulanate and cefuroxime retain an excellent activity against H. influenzae, while cefaclor lost some of its activity. The rate of susceptibility to azithromycin was markedly higher than that to clarithromycin; however, its ability to accumulate intracellularly while concentrations in serum and interstitial fluid remain low, should be considered, as it may represent a major drawback to its use in H. influenzae infections.

Adolescent↗
PubMed1996

In vitro susceptibilities of 176 clinical isolates of Streptococcus pneumoniae to 11 beta-lactams, erythromycin, and tetracycline.

One hundred seventy six consecutive, non-duplicate pneumococcal isolates from clinical specimens collected from November 1994 through February 1995 in nine general hospitals throughout Belgium were tested for their in vitro susceptibilities to penicillin, ampicillin, amoxycillin with and without clavulanate, cefaclor, cefuroxime, cefonicid, cefprozil, cefpodoxime, cefotaxime, imipenem, tetracycline, and erythromycin by means of the NCCLS microdilution test. The overall rate of decreased susceptibility to penicillin was 12.5%, including 6.3% of intermediately and 6.3% of fully resistant isolates. Penicillin, ampicillin amoxycillin, amoxycillin/clavulanate, cefuroxime, cefotaxime and imipenem had the highest activity on a weight basis (MIC50 < or = 0.008 microgram/ml), followed by cefpodoxime and erythromycin (MIC50 of 0.015 microgram/ml), cefprozil and tetracycline (MIC50 of 0.12 microgram/ml), and eventually, cefaclor and cefonicid (MIC50 of 0.5 microgram/ml). Aggregate rates of susceptible plus intermediately resistant isolates at NCCLS-recommended breakpoints, i.e. overall percentages of isolates likely to respond to increased antibiotic doses in vivo (except for meningitis), were 100.0% for imipenem and cefotaxime, 98.9% for amoxycillin with and without clavulanate, 93.8% for penicillin, and 90.9% for cefuroxime. Overall rates of susceptibility to erythromycin and tetracycline amounted to 78.4% and 72.7%, respectively. MIC values of all beta-lactams increased with those of penicillin. Ampicillin was equally active as penicillin against isolates with reduced susceptibility to the latter (MIC90 of 2 micrograms/ml); imipenem, cefotaxime, and amoxycillin with and without clavulanate however, were more active (MIC90 3, 1, and 1 doubling dilution, respectively, below that of penicillin), while cefpodoxime, cefuroxime, cefprozil, cefonicid, and cefaclor on the other hand, were less active (MIC90, 1, 1, 2, 5, and 5 doubling dilutions, respectively, above that of penicillin). In conclusion, the present data confirm that pneumococcal resistance to penicillin has increased in Belgium, suggest that resistance to erythromycin may have stabilised, and reveal an unexpectedly high rate of resistance to tetracycline. Imipenem was the most active antibiotic tested overall, and amoxycillin with or without clavulanate the most active oral antibiotic, with activity almost similar to that of cefotaxime.

Anti-Bacterial Agents↗
PubMed1996

Management of rhesus isoimmunization by preimplantation genetic diagnosis.

A genetic assay by single blastomere analysis was developed for rhesus (RhD) blood group typing of early cleavage stage embryos. The method, which is based on the simultaneous amplification of an RhD-specific sequence and an internal control in single cells, was applied for the selective transfer of RhD-negative embryos in a family of an RhD sensitized woman and a heterozygote partner. The RhD status of two out of three biopsied embryos was determined. According to their amplified products, both were typed as RhD-negative and transferred to the uterus. Pregnancy was not achieved.

Adult↗
PubMed1996

Human follicular nitric oxide pathway: relationship to follicular size, oestradiol concentrations and ovarian blood flow.

Nitric oxide (NO) has been suggested to be involved in ovarian physiology. Our aim was to study follicular nitrite and nitrate (NO3/NO2) levels in women undergoing in-vitro fertilization (IVF), and to examine their relationship to follicular size, oestradiol concentrations, and ovarian artery and intra-ovarian blood flow as measured by Doppler ultrasound. A total of 15 patients from the IVF programme of Hadassah University Hospital, Mt Scopus, Israel, participated in the study. Detailed transvaginal ultrasonographic examination was performed before ovum collection, and ovarian artery and intra-ovarian blood flow were measured. While aspirating the follicles, the content of two to four of the follicles in each ovary was collected individually, the volume of follicular fluid measured, and NO3/NO2 concentrations were determined. A statistically significant positive correlation was found between follicular fluid NO3/NO2 concentrations and follicular volume (r = 0.76), as well as between NO3/NO2 concentrations and oestradiol concentrations (r = 0.63). A statistically significant negative correlation was found between follicular fluid NO3/NO2 concentrations and ovarian flow parameters as well as between NO3/NO2 concentrations in follicles containing 4-5 ml and ovarian artery pulsatility index.

Adult↗
PubMed1996

Hypertension promotes coronary calcium deposit in asymptomatic men.

Despite its important role in coronary disease, coronary atherosclerosis has been poorly investigated in uncomplicated hypertension. Therefore, we evaluated the presence and amount (score) of coronary calcium with ultrafast computed tomography in 73 pairs of age-matched asymptomatic hypertensive or normotensive men. We also estimated the extent of peripheral atherosclerosis as the number of arterial sites (carotid, aortic, femoral) with echographic plaque. Compared with normotensive men, hypertensive men had more frequent coronary calcium (63% versus 47%), a higher calcium score (57 +/- 111 versus 18 +/- 38), and an odds ratio of calcium deposit of 1.95 (with confidence intervals [CI] 95%, 1.01 to 3.79) for any score and of 2.38 (95% CI, 1.02 to 5.52) or 4.84 (95% CI, 1.53 to 15.3) for scores above 50 or 100, respectively. Hypertensive men showed correlations of calcium score with age and hypertension duration but not with the height of blood pressure, and the odds ratio of calcium deposit between extensive and minor peripheral atherosclerosis was 4.67 (95% CI, 1.41 to 15.45) for any score and 8.63 (95% CI, 2.10 to 35.5) or 8.13 (95% CI, 1.64 to 40.3) for scores above 50 or 100. Thus, high blood pressure and in particular its duration rather than its value promotes the presence and overall extent of coronary calcium, a potential predictor of sudden coronary death, in parallel with the extent of peripheral atherosclerosis. The mechanisms of the interaction of hypertension and coronary calcification may be multifactorial and not specific to hypertension.

Adult↗
PubMed1996

Inhibition of hypertension by peripheral administration of antisense oligodeoxynucleotides.

We administered liposome-encapsulated antisense oligodeoxynucleotide targeted to angiotensinogen mRNA peripherally to spontaneously hypertensive rats to test whether peripheral angiotensinogen reduction would lower their hypertensive blood pressures and to determine the role of peripheral angiotensinogen in the modulation of hypertension. Using in vitro translation techniques, we tested the sequence specificity of the antisense sequence. The selected antisense sequence decreased angiotensinogen production in vitro, enabling us to distinguish between specific and nonspecific effects. To increase the efficiency of peripheral and hepatic antisense delivery, oligonucleotides were liposome encapsulated and intra-arterial administration. Confocal microscopy was used for determination of the hepatic distribution of fluorescently labeled antisense. Encapsulated antisense molecules were seen to be distributed within liver tissue 1 hour after injection; however, little or no uptake was observed with the unencapsulated oligonucleotides. We also determined the physiological effects of antisense oligodeoxynucleotide targeted to liver angiotensinogen mRNA. Administration of liposome-encapsulated antisense significantly decreased hypertensive blood pressures to normotensive levels compared with scrambled control oligonucleotides, unencapsulated antisense, and empty liposomes (P = .013). These data were supported by biochemical changes elicited by the antisense treatment. Rats receiving liposome-encapsulated antisense had significantly lowered peripheral angiotensinogen and angiotensin II levels compared with control groups (P < .05). No significant heart rate changes were observed in the antisense or control groups. These results suggest that peripheral angiotensinogen plays a role in the maintenance of hypertensive blood pressure in this model of hypertension and that peripheral administration of antisense molecules is possible with organ-targeted delivery mechanisms.

Angiotensin II↗
PubMed1996

Characterization of intraperitoneal cytokines and nitrites in women with severe ovarian hyperstimulation syndrome.

OBJECTIVE: To assess the potential involvement of cytokines and nitrites in the hyperpermeability characterizing the ovarian hyperstimulation syndrome (OHSS). DESIGN: A controlled clinical study comparing peritoneal fluid (PF) from patients with severe OHSS and from non-OHSS controls. SETTING: Women hospitalized with severe OHSS in three tertiary medical centers. PATIENTS: Twelve patients with severe OHSS necessitating paracentesis and 20 non-OHSS controls. INTERVENTIONS: The criteria for ultrasound-guided paracentesis were tense ascites, hydrothorax, hemoconcentration, or oliguria. MAIN OUTCOME MEASURES: Interleukin (IL) 1 beta IL-1 receptor agonist, IL-2, IL-6, IL-8, and tumor necrosis factor alpha (TNF alpha) levels in PF were assayed by ELISA; nitrites were measured by the "Griess" reaction. Estradiol and P were determined by RIA. RESULTS: Ovarian hyperstimulation syndrome patients had significantly higher PF IL-6 (3,523 versus 30 pg/mL), TNF alpha (14 versus 4.2 pg/mL), and IL-8 (1,695 versus 900 pg/mL). In the serum, only IL-6 levels were significantly higher (375 versus 11 pg/mL). Conversely, nitrite levels were significantly lower in PF of OHSS patients (0.5 versus 34 nmol/mL). Interleukin 1 levels were higher and IL-1 receptor antagonist levels were lower in OHSS patients, suggesting potentially increased biologic potency of IL-1. CONCLUSION: These findings suggest that these substances could be involved in mediating the capillary hyperpermeability characterizing this syndrome.

Ascitic Fluid↗
PubMed1996

[Dopamine slows phagocytosis of rods from bovine pigment epithelium in vitro trough D1 receptor].

Photoreceptor disc shedding and their phagocytosis by the retinal pigment epithelium undergo a daily rhythm entrained by an intrinsic oscillator involving melatonin and dopamine in non-mammals. Such a mechanism is not demonstrated in mammals, but the rhythm of photoreceptor renewal can be modulated by exogenous melatonin and dopamine. The present experiments were designed to show whether a direct action of DA occurs on pigment epithelial cells, and to identify the receptor mediating this action. Primary cultures of bovine retinal pigment epithelium were incubated with bovine rod outer segments in the presence of dopamine, D1 and D2 agonists, D1 antagonist and forskolin. Dopamine, D1 agonist and forskolin decreased phagocytosis, while D2 agonist was inactive. Thus dopamine slows pigment epithelium phagocytosis in vitro through a D1 receptor. Increased phagocytosis following blockade of the receptor by an antagonist suggests a more complex modulation of phagocytosis by dopamine.

Animals↗
PubMed1996

Influence of sialic acid on erythrocyte aggregation in hypercholesterolemia.

The respective role of adhesive forces induced by fibrinogen and repulsive forces induced by erythrocyte sialic acid content on erythrocyte aggregation, was investigated in hypercholesterolemic and control subjects. Aggregation index (AI) and disaggregation shear rate threshold (gamma t) were determined in the presence of either autologous plasma or dextran. Compared with controls, fibrinogen (p < 0.001) and aggregation parameters (AI p < 0.01; gamma t p < 0.01) were higher in hypercholesterolemics while erythrocyte sialic acid content (p < 0.001) was lower; in addition total serum sialic acid was increased (p < 0.01). The aggregation properties of erythrocytes, independent of plasma environment using dextran as a bridging macromolecule, showed an enhanced disaggregation shear rate threshold and an inverse relationship with erythrocyte sialic acid content. We conclude that decreased erythrocyte sialic acid content may intensify the effect of fibrinogen on aggregation and disaggregation of erythrocytes and participate in the development of atherothrombotic complications.

Erythrocyte Aggregation↗
PubMed1995

Extracoronary atherosclerotic plaque at multiple sites and total coronary calcification deposit in asymptomatic men. Association with coronary risk profile.

BACKGROUND: Recent studies have suggested that knowledge of the extent of subclinical atherosclerosis may improve prognostic information in subjects at risk of cardiovascular disease. Therefore, we tested the value of extracoronary plaque detected with echography at multiple sites and that of total coronary calcification deposit evaluated with ultrafast computed tomography for predicting the risk of coronary events estimated on the basis of traditional risk factors. METHODS AND RESULTS: We analyzed in 618 asymptomatic at-risk men the extent of extracoronary atherosclerosis, as assessed with ultrasound imaging of carotid, aortic, and femoral sites and coded as number of disease sites (none, one, two, or three) on the basis of the presence of plaque at each site, and the amount of total coronary calcification deposit, as evaluated with ultrafast computed tomography and coded as grade 0, 1, 2, or 3 on the basis of the determination of a total coronary calcium score. Concomitantly, age, systolic pressure, total and HDL cholesterol levels, current smoking, presence of diabetes, and presence of ECG left ventricular hypertrophy (ECG-LVH) were evaluated with the goal of estimating coronary risk with the use of the Framingham Study risk algorithm. The prevalence rates of at least one extracoronary disease site and coronary calcification (any grade) were high (72% and 63%). There was a strong association between the number of extracoronary disease sites and the grade of coronary calcification (P < .001). As the number of extracoronary disease sites increased, age, systolic pressure, smoking frequency, and number of risk factors increased (P < .001). As the grade of coronary calcification increased, age and systolic pressure increased (P < .001), as did the number of risk factors (P < .01). The estimated coronary risk increased with the number of extracoronary disease sites and the grade of coronary calcification (P < .001). The odds ratio of coronary risk between three and no extracoronary disease site was 2.37 (95% confidence interval [CI], 1.08 to 5.21), whereas that between grade 3 and grade 0 of coronary calcification was 1.79 (95% CI, 0.94 to 3.40). CONCLUSIONS: In an apparently healthy population, the extracoronary atherosclerotic burden as measured with multiple-site echography appears to be more powerful than the ultrafast computed tomography-detected coronary calcium burden in reflecting the multifactorial coronary risk profile. However, only men were included in the present study, and the present findings cannot be extrapolated to women.

Adult↗
PubMed1995

Mitochondrial beta-oxidation of 2-methyl fatty acids in rat liver.

The mitochondrial beta-oxidation of 2-methyl fatty acids was studied with coupled rat liver mitochondria and purified enzymes. Measurements of mitochondrial respiration supported by 2-methyl fatty acids, straight chain fatty acids, or their coenzyme A (CoA) thioesters revealed that free short-chain and medium-chain 2-methyl fatty acids are oxidized nearly or as efficiently as are their straight chain analogs. Long-chain 2-methyl hexadecanoyl-CoA is also oxidized, although more slowly than its unbranched counterpart. However, medium-chain 2-methyldecanoyl-CoA, in contrast to its unbranched analog, is not oxidized at all. Of all acyl-CoA dehydrogenases only long-chain acyl-CoA dehydrogenase acts on medium-chain and long-chain 2-methylacyl-CoA thioesters. The resultant 2-methyl-2-enoyl-CoA thioesters are substrates of the mitochondrial trifunctional beta-oxidation complex which catalyzes the sequential hydration, dehydrogenation, and thiolytic cleavage of 2-methyl-substituted substrates to yield chain-shortened acyl-CoA thioesters and propionyl-CoA. The matrix enzymes L-3-hydroxyacyl-CoA dehydrogenase and 3-ketoacyl-CoA thiolase, in contrast to enoyl-CoA hydratase, are inactive with medium-chain and long-chain 2-methyl-substituted chain substrates. The specificity of the beta-oxidation enzymes toward 2-methyl-branched substrates forms the basis for assays of long-chain acyl-CoA dehydrogenase and the trifunctional beta-oxidation complex in the presence of their mitochondrial isozymes. It is concluded that rat liver mitochondria can oxidize 2-methyl fatty acids, but does so most effectively with medium-chain and short-chain ones that can enter mitochondria directly in a carnitine-independent manner.

Acyl Coenzyme A↗
PubMed1995

Distribution and spatial geometry of dopamine interplexiform cells in the retina. II. External arborizations in the adult rat and monkey.

The morphology and distribution of dopaminergic interplexiform cells in adult rat and monkey retinas were analyzed to determine any correlation with the function of dopamine in the outer retinal layers. The retinas were processed as whole mounts for tyrosine hydroxylase immunohistochemistry. There was a network formed by the sclerally directed processes of interplexiform cells in the inner nuclear, outer plexiform, and outer nuclear layers running throughout the retina. Their density was higher in the superior retina than in the inferior retina of the rat and was especially high in the superior temporal quadrant. The external network in this quadrant was significantly less dense in the monkey than in the rat, as are the interplexiform cells. The somata of interplexiform and other dopaminergic cells were about the same size in both rats and monkeys. Computer-assisted reconstruction of external arborizations of individual cells showed that external processes lay very close to horizontal and photoreceptor cells and also to blood capillaries. Because they were long, thin, and highly varicose; branched at right angles; and often arose from an axon hillock, the external processes were identified as axons. Therefore, we define the dopaminergic interplexiform cells as multiaxonal neurons, with at least one outwardly directed axon that reaches the outer plexiform layer. The function of the network of external processes from the interplexiform dopaminergic cells is discussed in terms of modulating the release of dopamine to external layers.

Animals↗