CGP 43371 paradoxically inhibits development of rabbit atherosclerotic lesions while inducing extra-arterial foam cell formation.

Ansamycins are hypolipidemic compounds which, when administered to various animal species, dramatically lower high density lipoprotein (HDL) cholesterol levels, in addition to reducing the levels of other lipoprotein classes. The current study tested one of these ansamycins (CGP 43371) for its hypolipidemic and anti-atherosclerotic activity in cholesterol-fed rabbits. Rabbits were fed a 0.25% cholesterol-enriched diet with or without admixed CGP 43371, equivalent to 30 mg/kg per day for 16 weeks. Compared with control rabbits, CGP 43371 treatment lowered total cholesterol levels (46%, P<0.05) and lipoprotein cholesterol levels (HDL, 58%; VLDL, 49% [both P<0.05]; LDL, 28% [not significant]). Despite the dramatic lowering of HDL cholesterol levels, aortic atherosclerosis, assessed by grossly visible sudanophilia, was significantly inhibited versus controls (total aorta=38%; aortic arch=32%; thoracic aorta=60%). Of particular note in CGP 43371-treated rabbits was a striking splenomegaly, which correlated with the presence of massive accumulations of macrophage foam cells in the splenic red pulp. We speculate that CGP 43371 inhibits the development of atheroselerotic lesions in rabbits by both a hypolipidemic mechanism, and by a mechanism(s) in which macrophage foam cells accumulate in the spleen.

Enhanced expression of renal endothelin-converting enzyme-1 and endothelin-A-receptor mRNA in rats with interstitial fibrosis following ureter ligation.

Endothelin-1 (ET-1) has been implicated in many chronic renal glomerular diseases. The purpose of this study was to investigate whether the levels of mRNA expression of endothelin-converting enzyme-1 (ECE-1) and endothelin-A- and -B- (ET(A) and ET(B)) receptors are altered during the progression of interstitial fibrosis following ureter ligation. Rats were subjected to left ureter ligation or a sham operation and euthanized 5 days afterward. Kidneys were fixed in Carnoy's fixative, embedded in paraffin, and sectioned for assessment of interstitial fibrosis by staining for collagen III using immunofluorescence techniques. The area occupied by collagen staining was quantified by image analysis. Kidneys from obstructed rats showed a 54% increase in the area occupied by collagen III staining compared to the contralateral kidney, and an 89% increase compared to sham-operated kidneys. The mRNA levels of ECE-1, as well as ET(A)- and ET(B)-receptors in the kidney were analyzed by Northern blots. It was found that the ECE-1 and ET(A)-receptor mRNA levels in kidneys subjected to ureter ligation increased by 92% and 71%, respectively, when compared with those obtained from the contralateral kidneys. In contrast, mRNA levels of ET(B)-receptors were not significantly different between the two groups. These results suggest that ET-1, through interaction with the ET(A)-receptors, may play a role in the progression of interstitial fibrosis following ureter ligation.

Attenuation of puromycin aminonucleoside-induced glomerular lesions in rats by CGS 26303, a dual neutral endopeptidase/endothelin-converting enzyme inhibitor.

Endothelin-1 (ET-1) has been implicated in the pathogenesis of various renal diseases. The purpose of this study was to investigate the effect of CGS 26303, an endothelin-converting enzyme (ECE) inhibitor, on puromycin aminonucleoside (PA)-induced nephrosis in rats. The animals (three groups; n = 8 per group) received 50 mg/kg PA or NaCl, intravenously. CGS 26303 (5 mg/kg/day, s.c. via osmotic minipumps) or vehicle was administered to the PA-treated animals for 4 weeks, starting within 5 min after PA injection. Uninephrectomy was performed 2 weeks after PA to accelerate the renal damage. Rats received no treatment between 4 and 8 weeks. At 8 weeks rats were euthanized and kidneys removed for histology and analysis for mRNA levels of endothelin-A- and -B- (ET(A) and ET(B)) receptors and ECE-1. Glomeruli (100 glomeruli/section; 800/group) were graded as normal (N), mild lesion (ML = few periodic acid-Schiff positive [PAS+] droplets and small adhesions to Bowman's capsule), and moderate to severe lesion (SL = many PAS+ droplets, adhesions to and thickening of Bowman's capsule, mesangial expansion, and cystic dilations of glomerular capillaries). In the PA + vehicle group N, ML and SL were 39.5%, 11.9% and 48.6%, respectively, while the respective values were 68.3%, 9.4%, and 22.3% in PA + CGS 26303-treated rats. However, the renal mRNA levels of ECE-1 and ET(A)- and ET(B)-receptors were not significantly different among the three groups. These results confirm the efficacy of ECE inhibition in this disease model. On the other hand, the mRNA data suggest that either there was no change in the expression of the genes examined or their levels had already returned to normal by the end of the experiment.

The in vitro and ex vivo antioxidant properties, and hypolipidemic activity of CGP 2881.

This report describes the in vitro and ex vivo antioxidant properties of a new antioxidant, CGP 2881. This compound is structurally similar to probucol, in that both compounds contain bis-tertiary butyl phenyl groups. However, CGP 2881 consistently inhibited CuSO4 (Cu2+)- and macrophage (MO)-induced oxidation of human low density lipoproteins (LDL) more potently than equimolar concentrations of probucol. CGP 2881 (1 mumol/l) prolonged the lag phase of diene formation during Cu(2+)-induced LDL oxidation by 3.4 versus 1.5-fold prolongation with 1 mumol/l probucol (P < 0.05 vs CGP 2881). The IC50 for inhibiting the formation of Cu(2+)-induced thiobarbituric acid-reactive substances (TBARS) was 0.15 mumol/l for CGP 2881, versus approximately 10 mumol/l for probucol. The IC50 for MO-induced oxidation of LDL (TBARS) was 0.64 mumol/l. In contrast, 1 mumol/l probucol failed to inhibit MO-induced oxidation of LDL. Treatment of cholic acid/cholesterol-fed rats with CGP 2881 (50 mg/kg per day, orally for 5 days) inhibited ex vivo Cu(2+)-induced oxidation (TBARS) of the very low density lipoproteins (VLDL) + LDL lipoprotein fraction by 93% versus vehicle controls (P < 0.0001), and prolonged the lag phase for Cu(2+)-induced diene formation by 3.4-fold over vehicle-treated controls. Five days of orally administered CGP 2881 reduced plasma total cholesterol and LDL cholesterol levels to 55 and 54% of vehicle-treated controls, respectively (P < 0.05). In contrast, probucol had no appreciable effect on plasma total cholesterol or LDL cholesterol levels, unless administered for longer than 5 days. Treatment of hypercholesterolemic rabbits with 50 mg/kg per day orally for 5-12 days delayed the lag phase of diene formation during LDL oxidation by 4.3-fold over controls. However, the relative antioxidant potencies of CGP 2881 and probucol seen with oral administration to hypercholesterolemic rabbits were reversed when the compounds were given intravenously. In addition, the effects of these antioxidants were potentiated when given to normocholesterolemic rabbits compared to hypercholesterolemic animals. These data establish that CGP 2881 demonstrates hypolipidemic activity and is a substantially more potent antioxidant than probucol (in vitro and ex vivo). CGP 2881 may be useful as a new antioxidant tool in the effort to better understand the atherogenicity of oxidized LDL (oxLDL).

Investigation of the bottleneck leading to the domestication of maize.

Maize (Zea mays ssp. mays) is genetically diverse, yet it is also morphologically distinct from its wild relatives. These two observations are somewhat contradictory: the first observation is consistent with a large historical population size for maize, but the latter observation is consistent with strong, diversity-limiting selection during maize domestication. In this study, we sampled sequence diversity, coupled with simulations of the coalescent process, to study the dynamics of a population bottleneck during the domestication of maize. To do this, we determined the DNA sequence of a 1,400-bp region of the Adh1 locus from 19 individuals representing maize, its presumed progenitor (Z. mays ssp. parviglumis), and a more distant relative (Zea luxurians). The sequence data were used to guide coalescent simulations of population bottlenecks associated with domestication. Our study confirms high genetic diversity in maize-maize contains 75% of the variation found in its progenitor and is more diverse than its wild relative, Z. luxurians-but it also suggests that sequence diversity in maize can be explained by a bottleneck of short duration and very small size. For example, the breadth of genetic diversity in maize is consistent with a founding population of only 20 individuals when the domestication event is 10 generations in length.

Aortic antioxidant defense and lipid peroxidation in rabbits fed diets supplemented with different animal and plant fats.

OBJECTIVE: To test the hypothesis that dietary fats, depending on the fat source, may modulate aortic lipid peroxidation and antioxidant protection. METHODS: Rabbits were fed a low fat (LF, 2 g/100 g corn oil) diet or LF enriched with 16 g/100 g (w/w) of corn oil (CO), corn oil plus cholesterol (23.5 mg/100 g diet, CO + C), bovine milk fat (MF), chicken fat (CF), beef tallow (BT) or lard (L). After a 30-day feeding period, aortic lipid peroxidation, as well as antioxidant enzymes and vitamin E were measured. RESULTS: In rabbits fed CO or L, aortic TBARS (a marker of lipid peroxidation) and total glutathione concentrations were greater but vitamin E levels were lower compared with the LF treatment. Moreover, in rabbits fed CO, elevated activities of glutathione peroxidase and glutathione reductase but lowered activity of superoxide dismutase were observed. In rabbits fed the remaining high fat diets, including the CO + C diet, aortic lipid peroxidation and antioxidant activities/levels did not differ from those fed LF. Feeding rabbits high-fat diets for 30 days did not induce aortic lipid deposition. CONCLUSIONS: The present results indicate CO, and possibly L, as the fat sources which significantly increase aortic oxidative stress. Because long-term disturbances in redox status may be implicated in atherogenesis, excessive dietary intake of CO or L may significantly contribute to the injury of the vessel wall.

Public perceptions of a radioactively contaminated site: concerns, remediation preferences, and desired involvement.

A public attitudes survey was conducted in neighborhoods adjacent to a radioactively contaminated site whose remediation is now under the auspices of the U.S. Department of Energy's Formerly Utilized Sites Remedial Action Program (FUSRAP). The survey's purpose was to ascertain levels of actual and desired public involvement in the remediation process; to identify health, environmental, economic, and future land-use concerns associated with the site; and to solicit remediation strategy preferences. Surface water and groundwater contamination, desire for public involvement, and potential health risks were found to be the most highly ranked site concerns. Preferred remediation strategies included treatment of contaminated soil and excavation with off-site disposal. Among on-site remediation strategies, only institutional controls that leave the site undisturbed and do not require additional excavation of materials were viewed favorably. Cost of remediation appeared to influence remediation strategy preference; however, no strategy was viewed as a panacea. Respondents were also concerned with protecting future generations, better assessment of risks to health and the environment, and avoiding generation of additional contaminated materials.

Nosocomial phaeomycotic cyst of the hand.

We present the case of an elderly man with chronic obstructive pulmonary disease who had a 4-month history of multiple fluctuant masses of the dorsum of the right hand, which began at the site of an intravenous catheter. Medications included inhaled and oral steroids. Fungal cultures of the fluid obtained grew a pigmented mold identified as Exophiala species after several routine cultures were reported as negative. The patient underwent radical excision of the masses and received a perioperative course of oral itraconazole. This is one of the first known cases of a possible nosocomially acquired phaeomycotic cyst. Unusual fungi should be considered in the differential diagnosis of skin lesions in immunocompromised patients.

Tourniquet-related hypotension in venous stasis ulcer excision.

Extremity tourniquets are widely used to achieve bloodless dissection in the surgical field. Excision of venous stasis ulcers (VSU) is aided by tourniquet use because of large dilated veins associated with venous stasis disease. We present 3 patients with hypotensive shock occurring 10 to 15 minutes after tourniquet release after excision of venous stasis ulcers. All patients had long histories of venous stasis changes and two-thirds had prior histories of deep vein thromboses and pulmonary embolism. Mean tourniquet inflation time was 34 minutes and there were electrocardiographic changes in two-third of the patients. All patients responded rapidly to standard resuscitation measures and in all 3 postoperative testing for pulmonary embolus and myocardial infarction was negative. Wound cultures revealed no organisms in 1 patient, mixed Gram-positive cocci in another, and greater than 10(5) Serratia marcescens in the third patient. Although small decreases in blood pressure and blood pH, and increases in blood lactate, PcO2, and creatinine phosphokinase, are normally associated with the use of extremity tourniquets, hypotensive shock has not been reported. The combined effect of tourniquet ischemia and venous stasis changes may cause hypotensive shock by (1) an endotoxic bolus upon tourniquet release, (2) pulmonary microembolization of platelet, fibrin, and leukocyte aggregates causing vasoactive substance release, and (3) synergistic effects of platelet-activating factor, a known mediator of endotoxic shock. The untoward events noted in these patients may be prevented by (1) proximal to distal dissection of the ulcer with initial ligation of large veins, (2) pretreatment with steroids and/or platelet-activating factor antagonists, and/or (3) slow release of the tourniquet.

Tissue oxygenation and blood flow on specialized and conventional hospital beds.

Despite the widespread use of specialty bed products, the physiological mechanism of their benefit has not been evaluated. In this study, healthy subjects were used to study transcutaneous oxygen tension (TcPo2) and laser Doppler blood flow in pressure sore-prone areas on air-fluidized, low-air-loss, and adjustable air-mattress beds relative to a standard hospital mattress with and without an egg-crate mattress overlay. Measurements were obtained over the sacrum with the subject in the prone and supine positions, and over a greater trochanter with the subject in the prone and 90-degree lateral positions. Our results on healthy volunteers suggest that the specialty bed products maintain TcPo2 better than a standard bed when tissue is weighted. Further, the Clinitron had significantly higher TcPo2 when weighted than each of the other beds. Laser Doppler blood flow was much more variable. The weighted trochanter on the standard bed had the lowest blood flow, which is consistent with the TcPo2 readings. However, the variability made the laser Doppler flow data less valuable than the TcPo2. In conclusion, these data indicate that several products, particularly the Clinitron, maintain TcPo2 of weight-bearing tissue, which may be an important mechanism in protecting against pressure sores.

Which dressing for split-thickness skin graft donor sites?

There is currently little agreement among surgeons regarding the dressing of choice for split-thickness skin graft donor sites, though many are available. In this article, I review the five major groups of dressings, open, semiopen, occlusive, semiocclusive, and biological. The different dressings in each group are described in terms of physiological basis for use, advantages, disadvantages, and practical application. Conclusions are reached regarding which donor site dressings might come closest to optimal for common clinical situations.

A prospective trial comparing Biobrane, Duoderm and xeroform for skin graft donor sites.

Many new dressings have been introduced for use on split-thickness skin graft donor sites in an effort to reduce pain at the donor site and decrease healing time, while maintaining a low infection rate and cost. To assess these factors in two such dressings, Biobrane (temporary wound dressing) (Winthrop) and Duoderm (hydrocolloid dressing) (Convatec), we compared them with a conventional fine mesh gauze dressing, xeroform, in a prospective, randomized study of 30 donor sites in the same number of patients. Wounds were considered healed when they were 100 per cent re-epithelialized and required no further dressings. Patient self-assessment of pain was quantified on a scale of zero to ten, with ten being the most severe pain. Donor sites dressed with xeroform had a healing time of 10.5 days, which was significantly better (p less than 0.05) than Duoderm (15.3 days) or Biobrane (19.0 days), although the protocol for Duoderm use (wound visualization at seven day intervals) extended the apparent healing times in this group. Duoderm was the most comfortable dressing (0.53 grade) when compared with Biobrane (1.44) and xeroform (2.41, p less than 0.05). No infections occurred in donor sites dressed with xeroform, but two developed in patients using Biobrane. One patient with a Duoderm dressing had a donor site infection during a drug-related neutropenic reaction. Xeroform was the least expensive dressing to use ($1.16 per patient), followed by Duoderm ($54.88 per patient) and Biobrane ($102.57 per patient). The results of our study confirm the usefulness of xeroform as a donor site dressing as it promotes relatively rapid healing, is easy to use and is inexpensive. We found Duoderm to be ideal for smaller donor sites when pain could be significantly reduced with minimal increase in cost. Biobrane is too costly and the infection rate too high for it to be used routinely as a skin graft donor site dressing.

Leukocytosis in rabbits with diet-induced atherosclerosis.

In cholesterol-fed rabbits the extent of monocyte involvement in atherogenesis may be influenced by the level of circulating leukocytes during hypercholesterolemia. We characterized the leukocytosis in rabbits fed either a 0.25% or a 0.1% cholesterol-enriched diet (0.25% or 0.1% rabbits, respectively). Circulating leukocytes were elevated by 1 week of feeding, and the elevation was sustained for at least 30 weeks. Differential counts were unchanged. Immature leukocytes were not seen, indicating that the leukocytosis was not due to premature release of bone marrow cells. Animals were free of bacterial or parasitic disease; selected rabbits with leukocytosis had normal body temperatures. Spleen weights averaged at least 100% higher in 0.25% rabbits but did not show histological evidence for hematopoiesis that could account for the leukocytosis. At approximately 22 weeks there was a second rise in leukocytosis in bilirubinemic 0.25% rabbits, suggesting that in the late stages of hypercholesterolemia, leukocytosis is related to liver failure. Cholesterol-fed rabbits also showed thrombocytosis. Existing leukocytosis and hypercholesterolemia were reversed to pretreatment levels by switching the rabbits to chow diets. In bone marrow from 0.25% rabbits, the mean number of cells per gram was greater (p less than 0.05) than that from normocholesterolemic rabbits. In 0.25% rabbits, the fraction of blood mononuclear cells showing phagocytosis of immunoglobulin G-coated red blood cells did not differ from that of controls, suggesting an unchanged population of these cells with regard to Fc and phagocytic function during hypercholesterolemia. These data suggest an effect (direct or indirect) of hypercholesterolemia on the production of leukocytes in the bone marrow and/or on the circulation kinetics of leukocytes in the blood.

Use of Histopaque for isolating mononuclear cells from rabbit blood.

This paper describes the use of Histopaque (Hp) density gradient medium and its advantage for separating mononuclear cells (mnc) from rabbit blood. Hp solutions of density (d) = 1.083 g/ml, 1.119 g/ml and 1:1 mixture of these solutions (final d = 1.103 g/ml) were compared to Ficoll-Paque (Fp, d = 1.077 g/ml) and Lymphopaque (d = 1.086 g/ml). The average leukocyte recovery was: Fp = 26% and Lp = 17%, while that with Hp was: Hp d = 1.083: 41%; Hp d = 1.119: 43%; Hp d = 1.103: 57%. Optimum mnc recovery (76%) was obtained with Hp d = 1.103. Average mnc purity for the various media was: Fp = 88% mnc; Lp = 91%mnc; Hp d = 1.083: 94% mnc; Hp d = 1.119: 93%; Hp d = 1.103: 94% mnc. Contamination was mainly from basophils. Viability was greater than 95% in all cases. Thus, Hp density gradient media provide increased recoveries of mnc from rabbit blood compared to Fp and Lp, while purity is not affected. Rabbit mnc appear to be denser than human mnc, which are recovered in greater numbers using Fp.

Immunohistochemical localization of apoprotein B in aortas from hyperlipemic swine. Preferential accumulation in lesion-prone areas.

In hyperlipemic swine, areas of the aortic arch that accumulate intravenously injected Evans blue dye (blue areas) appear to be more susceptible to early atherogenesis than adjacent areas that are devoid of dye uptake (white areas). We used immunofluorescence microscopy to determine the localization of apoprotein-B (apoB) in these blue and white areas, and in intimal cell masses (ICMs) of the abdominal aortas obtained from hyperlipemic and normolipemic swine. The results showed that before aortic lesions were visible grossly or microscopically, extracellular accumulations of apoB occurred preferentially in the thickened intima of blue areas and in ICMs of the abdominal aorta. Normal white areas in the aortic arch and abdominal aortas, and in the aortas obtained from control swine showed negligible immunoreactivity. Thus, the accumulation of apoB at anatomic sites predilected to early atherogenesis lends further evidence linking these lipoproteins with atherogenesis.

An ACTH-induced renal glomerular lesion in the mouse: immunofluorescence microscopy.

Mice were injected with adrenocorticotropic hormone (ACTH) and the glomerular lesion that was induced was studied by light and immunofluorescence microscopy. By light microscopy, kidneys from ACTH-treated mice showed typical ACTH-induced glomerular lesions. Immunofluorescence of kidneys from ACTH-treated mice revealed intense staining for IgG and IgM in the extraglomerular mesangium (EGM), in Bowman's space, and in the ascending thick limb of Henle near the macula densa. Staining for immunoglobulins was unchanged after treatment with acid buffer. Immunoreactivity for complement (C3) was confined largely to the EGM and Bowman's space. Staining for albumin was almost exclusively in Bowman's space or the peripheral glomerular tuft in discrete aggregates. The above patterns of IgG, IgM, C3 and albumin were seen in control mice, although much less frequently. The results show that in mice, treatment with ACTH results in the increased accumulation of plasma proteins in the juxtaglomerular apparatus (JGA). This effect may reflect a role for the JGA in the normal clearing of plasma proteins from the glomerulus and/or directly from the blood.

Localization of LDL in arteries: improvements in immunofluorescence procedures.

We have described the development of procedures used to localize LDL in arteries with atherosclerotic lesions from humans and experimental animal models. We have first illustrated data obtained from earlier cryostat studies, described the procedures, given examples of results of LDL localization in sections of paraffin-embedded blocks, and finally outlined the procedures used and examples for LDL localization in epoxy-embedded blocks. Future improvements in resolution of LDL localization will probably require performing electron microscopy on ultrathin sections of epoxy-embedded arteries followed by immunocytochemistry.

The development of an acth-induced renal glomerular lesion in Mus musculus. An ultrastructural study.

Male house mice (Mus musculus) were injected with 4 international units of ACTH daily for 1, 2, 3 and 4 weeks and with four units daily for four weeks followed by 8 units for 8 days. Light microscopy of kidneys showed a glomerular lesion characterised by the expansion of the mesangium, deposition of PAS positive material in the glomerular mesangium and extraglomerular mesangium hypertrophy of juxtaglomerular cells and a successive increase in oil red-O staining material in the glomerulus. Electron microscopy revealed the progressive accumulation in the mesangial matrix of three morphologically distinct forms of deposits: amorphous, globular and particulate. The accumulation of amorphous deposit apparently is partially responsible for the increased PAS positive staining of the mesangium. Globular (and possibly particulate) deposit probably corresponds to the oil red-O positive material. The evidence suggests that the deposits are extraglomerular in origin, but their chemical nature is unknown.

Hyperthyroidism with periodic paralysis.

Hyperthyroidism may be associated with hypokalemic periodic paralysis. Two cases are presented demonstrating intermittent attacks of flaccid paralysis associated with clinical symptoms, signs and laboratory findings of hyperthyroidism. During an attack, one patient had a serum potassium of 2.1 mEq. per litre.Various factors such as trauma, exposure to cold, excessive carbohydrate ingestion and certain medications have been stated to precipitate an episode of paralysis. Attacks may range from mild weakness to generalized flaccid paralysis with loss of deep tendon reflexes. Several reported patients have died owing to cardiac arrest or respiratory paralysis.During attacks, the serum potassium is usually in the range of 2.2 to 3.2 mEq. per litre. It is postulated that a metabolic abnormality affecting the muscle-cell membrane can occur in the hyperthyroid state resulting in a shift of potassium to the intracellular position, thus producing a situation of hyperpolarization of the muscle-cell membrane which in turn alters the muscle contractibility.The importance of recognizing the unusual association of hypokalemic periodic paralysis with hyperthyroidism is stressed because, with successful treatment of the hyperthyroidism, the episodes of paralysis disappear.