Dietary fish oil modulates macrophage fatty acids and decreases arthritis susceptibility in mice.

B10.RIII and B10.G mice were transferred from a diet of laboratory rodent chow to a standard diet in which all the fat (5% by weight) was supplied as either fish oil (17% eicosapentaenoic acid [EPA], 12% docosahexaenoic acid [DHA], 0% arachidonic acid [AA], and 2% linoleic acid) or corn oil (0% EPA, 0% DHA, 0% AA, and 65% linoleic acid). The fatty acid composition of the macrophage phospholipids from mice on the chow diet was similar to that of mice on a corn oil diet. Mice fed the fish oil diet for only 1 wk showed substantial increases in macrophage phospholipid levels of the omega-3 fatty acids (of total fatty acid 4% was EPA, 10% docosapentaenoic acid [DPA], and 10% DHA), and decreases in omega-6 fatty acids (12% was AA, 2% docosatetraenoic acid [DTA], and 4% linoleic acid) compared to corn oil-fed mice (0% EPA, 0% DPA, 6% DHA, 20% AA, 9% DTA, and 8% linoleic acid). After 5 wk this difference between the fish oil-fed and corn oil-fed mice was even more pronounced. Further small changes occurred at 5-9 wk. We studied the prostaglandin (PG) and thromboxane (TX) profile of macrophages prepared from mice fed the two diets just before being immunized with collagen. Irrespective of diet, macrophages prepared from female mice and incubated for 24 h had significantly more PG and TX in the medium than similarly prepared macrophages from male mice. The increased percentage of EPA and decreased percentage of AA in the phospholipids of the macrophages prepared from the fish oil-fed mice was reflected in a reduction in the amount of PGE2 and PGI2 in the medium relative to identically incubated macrophages prepared from corn oil-fed mice. When this same fish oil diet was fed to B10.RIII mice for 26 d before immunization with type II collagen, the time of onset of arthritis was increased, and the incidence and severity of arthritis was reduced compared to arthritis induced in corn oil-fed mice. The females, especially those on the fish oil diet, tended to have less arthritis than the males. These alterations in the fatty acid pool available for PG and leukotriene synthesis suggest a pivotal role for the macrophage and PG in the immune and/or inflammatory response to type II collagen.

Randomized controlled trial of topical hyperbaric oxygen for treatment of diabetic foot ulcers.

The effect of 2 wk of topical hyperbaric oxygen (THO) treatment on the healing of diabetic foot ulcers without associated gangrene was evaluated in a prospective, controlled, and randomized manner in 28 patients. There were 12 patients in the THO group (group 1) and 16 in the control group (group 2). Clinical management of the two patient groups was similar except for THO treatment in the group 1 patients. Clinical parameters, including age, sex, baseline fasting serum glucose levels, duration of diabetes mellitus, duration of foot ulcers, presence of peripheral neuropathy or arterial insufficiency, and evidence of osteomyelitis as determined by radiographs and/or radionuclide scans, were comparable in both groups of patients. No statistical differences (Student's t test) were seen in the number of microorganisms isolated from curettage cultures of the base of the ulcer at days 0, 7, and 14 of the study between groups 1 and 2. In contrast to previous studies, there was a paucity of anaerobic microorganisms isolated from these foot ulcers without associated gangrenous changes. Ulcer areas were estimated by multiplying the maximum width by the maximum length in millimeters at days 0, 7, and 14. Analysis of variance and Student's t test revealed progressive significant reductions in the ulcer areas in both groups when days 0, 7, and 14 were compared and in ulcer depths in both groups when days 0 and 14 were compared. However, such ulcer size changes did not differ statistically between the control and THO groups. A trend toward slower healing was observed in the THO group. Healing of diabetic foot ulcers was not accelerated by THO in this study.

Potentiation of D2-dopamine receptor-mediated suppression of zif 268 by non-competitive NMDA receptor antagonists in reserpinized rats.

Striatopallidal output neurons, which coexpress D2-dopamine receptors and NMDA receptors, are logically a potential site of interaction between corticostriatal glutamatergic input and dopaminergic systems. Recent hypotheses about the etiology of schizophrenia have implicated both excitatory amino acid and dopamine systems. The present study was designed to examine, in vivo, the interaction between D2-dopamine receptors and NMDA receptors in the regulation of the expression of the early immediate genes (IEGs), zif 268 and jun B, in striatopallidal neurons. We tested whether coadministration of NMDA antagonists interacted with the actions of the D2 agonist, quinpirole, on IEG expression following dopamine depletion with reserpine. When rats were pretreated with the non-competitive NMDA receptor antagonists, MK 801 (1 mg/kg) or PCP (20 mg/kg), together with quinpirole, the quinpirole reversal of reserpine induction of zif 268 mRNA was potentiated in all regions examined. MK 801 alone had no significant effect on reserpine induction of zif 268 mRNA. Pretreatment with the competitive NMDA receptor antagonist, CPP (5 mg/kg), did not significantly alter the dose response of zif 268 mRNA expression to quinpirole in any region. There was no significant effect of MK 801 on jun B mRNA expression, either on the response to quinpirole or when administered alone with reserpine. Our findings provide evidence of an interaction between the NMDA receptor channel system and the D2-dopamine system on a molecular level in striatopallidal neurons carrying output from the basal ganglia.

[3H]spiperone binds selectively to rat striatal D2 dopamine receptors in vivo: a kinetic and pharmacological analysis.

We have determined the kinetic, equilibrium saturation, and pharmacological characteristics of [3H]spiperone ([3H]SPIP) binding to rat brain regional particulate fractions following i.v. injections of [3H]SPIP and compared these parameters to those determined in vitro with traditional ligand-homogenate binding assays. [3H]SPIP binding to rat striatum in vivo and in vitro occurs to a single class of non-interacting binding sites which possess the pharmacological properties of a D2 dopamine (DA) receptor. The potencies of neuroleptic drugs in inhibiting DA receptor-mediated behaviors correlate with their potencies at displacing striatal [3H]SPIP binding in vivo. While striatum possesses a similar density of [3H]SPIP binding sites in vivo (34 pmol/g) and in vitro (31 pmol/g), binding affinity in vivo is about 200 times lower than in vitro. This difference in binding affinities appears to arise from alterations of [3H]SPIP association and dissociation rate constants brought about by tissue homogenization. The implications of our findings for external imaging of DA receptors and studies of DA receptor function in human brain homogenates are discussed.

Striatal D1- and D2-dopamine receptor sites are separately detectable in vivo.

We have characterized in particulate fractions of normal rat striatum the in vivo binding kinetics, binding affinity, and pharmacological profiles of [3H]SCH 23390, a ligand selective for the D1-subtype of dopamine (DA) receptor, and compared these to [3H]spiperone, a ligand classically associated with the D2 DA receptor subtype. The pharmacological specificity of each ligand's in vivo binding is very similar to binding to striatal homogenates in vitro. While similar maximum numbers (Bmax) of striatal binding sites exist in vivo compared to in vitro for both ligands, binding affinities in vivo for both ligands are reduced 125- to 200-fold compared to in vitro. In vivo binding of [3H]SCH 23390 to striatum is not increased by dopamine denervation produced by 6-hydroxydopamine lesions of the nigrostriatal pathway. In vivo binding of [3H]SCH 23390 and [3H]spiperone to striatum is not significantly reduced by increased synaptic concentration of dopamine following D-amphetamine administration. 125I-SCH 23982, the iodinated analogue of SCH 23390, localizes very highly to dopaminergic forebrain areas following i.v. administration. External imaging of mammalian and human brain D1-receptors is potentially feasible with this ligand.

Apparent synaptic dopamine deficiency induced by withdrawal from chronic cocaine treatment.

The effects on motor behavior and forebrain dopamine (DA) synaptic function of withdrawal from chronic cocaine treatment were examined with simultaneous activity monitoring and microdialysis in nucleus accumbens. Rats exhibited behavioral sensitization to daily 30 mg/kg i.p. cocaine. After 18 days of daily cocaine and 7 days of withdrawal, dialysate DA and homovanillic acid (HVA) levels were reduced 36-38%, consistent with a synaptic DA deficiency.

Postnatal development of D1 dopamine receptors in the medial prefrontal cortex, striatum and nucleus accumbens of normal and neonatal 6-hydroxydopamine treated rats: a quantitative autoradiographic analysis.

The postnatal development of dopamine (DA) D1 receptors in the medial prefrontal cortex (mPFC), striatum (STR) and nucleus accumbens (NAC) of control and perinatally 6-hydroxydopamine (6-OHDA) lesioned rats was examined using quantitative autoradiography of 3H-SCH 23390 binding. D1 receptors are present at one week and increase only slightly to a stable level by 2 weeks in the STR and NAC. Their ontogeny is not altered by intracisternal injection of 6-OHDA 5 days after birth. A biphasic pattern of appearance of D1 receptors was found in the mPFC. D1 receptors are present in the mPFC at 1 week, increase 3-fold by 2-3 weeks, and then decline at 4 and 6 weeks. 6-OHDA lesions do not significantly alter this pattern. At all postnatal ages. D1 receptor binding in the mPFC exhibits a laminar distribution with increased receptor density in deep cortical layers (V, VI) compared to more superficial cortical layers (I, II). Both superficial and deep layers of D1 receptors in the mPFC show similar postnatal developmental patterns. DA turnover rates are consistently about 10-fold higher in frontal pole compared to remainder of forebrain at all postnatal ages. Early 6-OHDA lesions increase DA turnover in forebrain, but lead to a persistent reduction in DA turnover in frontal pole by 2 weeks of age.

New insulin replacement technologies: overcoming barriers to tight glycemic control.

New insulin analogues act more quickly, allowing better postprandial glycemic control and making intensive control easier. New methods of delivering insulin, notably inhaled insulin, will soon provide alternatives to painful injections. Improved glucose sensors may eventually make an artificial pancreas possible.

Infections in the diabetic host.

The presence of the diabetic state seems to predispose patients to more severe and unusual types of infections. Awareness and early recognition of these sometimes devastating problems, coupled with appropriate medical and surgical treatment and aggressive metabolic control of diabetes, provide the maximum opportunity for healing and recovery.

Prostaglandin biosynthesis and metabolism in rat brain slices.

Prostaglandin F2alpha and E were measured in the slices and in the media after incubation of rat brain slices. About 5 to 10 times more prostaglandin F2alpha than prostaglandin E was found, most of which was secreted into the media. In the absence of oxygen or in the presence of indomethacin, prostaglandin levels in both the slices and media were reduced. Serotonin, norepinephrine, epinephrine, and DOPA, at 10(-3) M concentrations, increased the prostaglandin F2alpha/E ratio in both the media and slices. The levels of prostaglandins F2alpha found in the slices and media when the slices were incubated with prostaglandin E2 increased significantly, this increase being independent of the presence of indomethacin. This suggests that prostaglandin E2 was being converted to F2alpha by a prostaglandin E2 9-ketoreductase in the rat brain slices.

Inhibition of ethylene biosynthesis by salicylic Acid.

Salicylic acid inhibited ethylene formation from ACC in self-buffered (pH 3.8) pear (Pyrus communis) cell suspension cultures with a K(1) (app) of about 10 micromolar after 1 to 3 hours incubation. Inhibition appeared noncompetitive. Among 22 related phenolic compounds tested, only acetylsalicylic acid showed similar levels of inhibition. Inhibition by salicylic acid was inversely dependent on the pH of the culture medium and did not require a continuous external supply of salicylate. When compared to known inhibitors of the ethylene forming enzyme, cobalt, n-propyl gallate, and dinitrophenol, inhibition by salicylic acid most closely resembled that by dinitrophenol but salicylic acid did not produce the same degree of respiratory stimulation. Results are discussed in terms of other known effects of salicylic acid on plants, pH-dependency, and the possible influence of salicylic acid on electron transport.

Modification of guinea pig lung anaphylaxis by central nervous system (CNS) perturbations.

Since several studies indicate that protection from lethal anaphylaxis is mediated by anterior hypothalamic (AH) lesions, we investigated the hypothesis that central nervous system perturbations can modify release of mediators from antigen-challenged sensitized lungs. Three types of perturbations were made in guinea pigs: AH perturbation (electrodes inserted and the current was applied), anterior hypothalamic sham (AS) (electrodes placed as in the AH group but no current was passed), and posterior hypothalamic (PH) perturbation (electrodes placed and the current was applied). A control group was sham operated (electrodes not inserted). Eleven days after the operation, guinea pigs receiving brain perturbations and half the control group were sensitized to the antigen ovalbumin. The other half of the control group received vehicle only (nonsensitized). Twenty-five days after this procedure, lungs were perfused in situ, and the outflows were collected before and after injection of antigen. The perfusates were assayed for immunoreactive prostaglandin and histamine, and the lungs were assayed for cAMP, guanosine monophosphate, and histamine. Release of mediators and changes in lung cyclic nucleotides after perfusion with antigen were significantly greater in all the antigen-sensitized compared to the nonsensitized animals. Within the anaphylactic groups, significant reductions in mediators and in cyclic nucleotides were found in the animals with perturbations of the AH region compared to the CO animals. The time course of mediator release was not altered. The results extend to the biochemical level, the observation that the perturbation of the AH region can markedly modify the anaphylactic response, and indicate that this effect may be due to altered release of mediators.

Salicylic acid: A new inhibitor of ethylene biosynthesis.

Salicylic acid and acetylsalicylic acid at concentrations of 10(-6)M to 10(-4)M effectively inhibit ethylene production by pear cell suspension cultures. Results suggest these acids act by blocking the conversion of 1-aminocyclopropane-1-carboxylic acid to ethylene.

Increased PGE2 from human monocytes isolated in the luteal phase of the menstrual cycle. Implications for immunity?

The reproductive hormones are implicated in the well documented sexual dimorphism in cellular and immune responses. Prostaglandins (PGs) are mediators of the immune response with their concentration and relative amounts being pivotal to their impact. In resident peritoneal macrophages isolated from mice we had previously noted that the cells from females synthesized significantly more PG than males. In these experiments we investigated whether PG metabolism in the human monocyte was influenced by gender and by stage of the menstrual cycle. Monocytes isolated from the female and activated in vitro with LPS produced on average significantly more PG into the medium than the males. Among females, significantly more PG was found in the medium from cells isolated during the luteal phase of the cycle than during the early follicular phase. It was also in this luteal phase in which the female differed substantially from males. We suggest that the in vivo hormonal changes associated with the menstrual cycle modulate monocyte synthesis of PG and other immune modulators such as IL-1. This could be a key to understanding differences in vulnerability between males and females as well as within phases of the cycle, to immune and inflammatory insult.

Gender differences in eicosanoid production from macrophages of arthritis-susceptible mice.

Collagen-induced arthritis (CIA) in rodents is an experimental animal model that shares many clinical and pathologic findings with rheumatoid arthritis in man. Our previous findings suggested that the amelioration of CIA in mice by a fish oil diet was associated with macrophage accumulation and metabolism of eicosapentaenoic acid and a subsequently altered prostaglandin (PG) profile. In these experiments, we examined the role of gender and found that macrophages from female arthritis-susceptible B10.RIII or B10.G mice synthesized more PG and thromboxane than macrophages isolated from the males. Compared with males, female mice had higher circulating anti-type II collagen antibodies but were less likely to develop CIA. Females, especially those on a fish oil diet, developed a much less severe disease than the males. This supports our hypothesis that the type and/or amount of eicosanoid produced from the macrophage may alter the course of experimentally induced arthritis.

Homozygosity in the major histocompatibility complex region influences natural killer cell activity in man.

The effect of homozygosity at HLA loci on natural killer (NK) cell activity has been examined. Lymphocytes obtained from heterozygous and homozygous individuals were incubated with 51Cr-labeled, NK-sensitive K562 cells at different effector/target ratios, and lytic activity was determined. Homozygous cells, obtained from individuals who are known HLA homozygotes (homozygous typing cells) and from selected families, had low NK activity compared to those heterozygous donors. This low cytotoxic activity had no correlation with sex, but did correlate with homozygosity at the HLA-A, B and/or DR loci. A significantly lower number of cells, which bind to anti-Leu 7 antibody, was found in homozygous donors. However, this reduced number of Leu 7+ cells could only partially account for the decrease in NK activity. These studies suggest that in some individuals homozygosity at HLA may be linked to genes that control NK activity.

A fish oil diet reduces the severity of collagen induced arthritis after onset of the disease.

We have previously reported that compared to a corn oil diet a fish oil diet (5% by weight) fed to B10R.III mice before the induction of collagen induced arthritis markedly reduced disease severity. In this study we determine whether a fish oil diet could reduce the severity of collagen induced arthritis if begun after the arthritis was clinically apparent. Mice were initially fed either a fish oil or corn oil diet and immunized with bovine type II collagen 4 weeks later. At the onset of collagen-induced arthritis, half of the corn oil fed mice were switched to fish oil and arthritis assessed on a weekly basis. Four weeks after the diet change until killing 5 weeks later, the mice switched to fish oil developed much less severe arthritis than the corn oil fed controls. Thus the severity index of corn oil fed mice ranged between 9.4 and 7.1; the severity index of fish oil fed mice was between 6.8 and 4.3 while the mice switched to fish oil ranged between 7.2 and 5.6. Analysis of peritoneal macrophages 13 weeks after immunization showed that macrophages from fish oil fed mice incorporated eicosapentaenoic acid into phospholipids and produced less arachidonate products than corn oil fed mice. There was no difference between macrophages obtained from mice switched from corn oil to fish oil and those maintained on fish oil with respect to fatty acid composition of membrane phospholipids or prostaglandin profile. These results suggest that arthritis severity may be modulated after the onset of CIA by altering the PG profile of macrophages present at inflammatory sites.