External ear reconstruction. Use of a pivoting helix, porous polyethylene implant

We have used the porous polyethylene, pivoting helix framework for ear reconstruction at RLAMC since 1989 with no major complications. Postoperatively, patients have an external ear that resembles a normal ear and is sturdy enough to support eye wear. The aesthetic results have been well received by the patients and their families (Fig 8). Most children are reluctant to undergo surgery; however, those patients with ear deformities often are eager for external ear reconstruction surgery, and the majority of our pediatric patients have been pleased with the postoperative results (Fig 9). The success of this procedure depends on a number of factors, including proper patient selection, suitable selection of materials for the reconstruction, the technical skills of the surgeon, and the surgical team's attention to detail in the intraoperative period. The perioperative nurse, functioning as the patient advocate, plays an integral role in the success or failure of this procedure.

The comparative toxicity of operational Air Force hydraulic fluids

The subchronic (26 day) oral toxicities of two AF hydraulic fluids (MIL-H-5606 [H5], MIL-H-83282 [H8]), a commercial phosphate ester (PE), and two candidate hydraulic fluids (low temperature version of MIL-H-83282 [LT] and chlorotrifluorethylene oligomers [polyCTFE]) were compared in male F-344 rats. Oral dosing was used in order to quickly compare these fluids to PolyCTFE, the only fluid at the time to have been tested in a 90-day inhalation study. Rats were initially dosed with 1.0 g/kg/day of each fluid. H8 increased alkaline phosphatase (ALKP) while LT produced an anemia and leukocytosis. Exposure to H5 fluid resulted in lymphocytopenia and persistent diuresis. Due to their greater toxicity, resulting in lethality in the first dosing study, only 0.5 g/kg/day of PE and PolyCTFE were administered in the second study. Exposure to PE (0.5 g/kg) resulted in an anemia and decreases in BW (day 10 until day 25), spleen/BW ratio, blood urea nitrogen (BUN), and creatinine (CREAT). PolyCREAT (0.5 g/kg) decreased BW (day 11 to the end of the study) and testicular weight. PolyCTFE (0.5 g/kg) increased relative spleen weights, various clinical chemistry parameters, and triggered a reversible diuresis. PolyCTFE (0.5 g/kg), PE (0.5 g/kg), and H5 produced an increase in absolute and relative liver weights compared to control livers. Peroxisomal beta oxidation, an indicator of peroxisomal proliferation, was significantly increased above control levels in the livers of all rats except the PE (0.5 g/kg) group, where the increase was not significant. Hydrocarbon nephropathy, indicated by increased levels of hyaline droplets in kidney tubules, was severe in H5, mild in H8, LT, and PolyCTFE (0.5 g/kg), and minimal in PE (0.5 g/kg). The MIL-H-83282 fluids (H8 and LT) were the least toxic hydraulic fluids. PolyCTFE and PE were the most toxic, with H5 intermediate.

Tetracycline-resistant propionibacteria from acne patients are cross-resistant to doxycycline, but sensitive to minocycline

Antibiotic-resistant propionibacteria are being isolated with increasing frequency from antibiotic-treated acne patients. Minimum inhibitory concentrations (MICs) of three tetracyclines, extensively used in acne therapy, were determined for 46 resistant and 19 sensitive propionibacteria isolates. Sensitive strains were inhibited by < or = 1 microgram/ml of all three tetracyclines. For every resistant strain tested, the MIC of tetracycline exceeded that of doxycycline which, in turn, exceeded that of minocycline. The mean MIC for resistant strains was 20.61 +/- 4.56 micrograms/ml of tetracycline, 9.70 +/- 2.03 micrograms/ml of doxycycline and 1.95 +/- 0.35 micrograms/ml of minocycline. In order to determine whether these strains could be inhibited by concentrations of minocycline achievable in vivo, serum levels of minocycline were determined in acne patients receiving either the recommended dose of 50 mg b.d. (20 males, 14 females), or twice this dose (21 males, 12 females). Serum levels were significantly higher (P < 0.001, Student's t-test) in patients receiving 100 mg b.d. Males on 50 mg b.d. had significantly lower serum levels than females on the same dose (P < 0.05. Student's t-test). For all patients, the mean serum level on high-dose minocycline was 2.46 +/- 0.45 micrograms/ml, compared with 1.38 +/- 0.30 micrograms/ml on the smaller dose. These results indicate that tetracycline-resistant propionibacteria should be considered clinically minocycline sensitive, if patients who harbour such strains are prescribed 100 mg b.d. The recommended dose of minocycline for treating acne, especially in male patients, should be re-assessed.

Oestrogen and progesterone receptors in colorectal cancer and human colonic cancer cell lines

Receptors for oestrogen (ER) and progesterone (PR) were assayed in tissue from 17 patients with colorectal cancer and five colonic cancer cell lines using enzyme immunoassays. ERs and PRs were detected in 15 and 17 cancers respectively, although the levels detected were low: median (range) ER 1.3 (0-11.3) and PR 3.9 (0.3-10.2) fmol per mg protein. These values were not significantly different from median (range) levels of ER (1.1 (0.6-3.0) fmol/mg) and PR (1.9 (0.5-3.2) fmol/mg) detected in normal mucosa. There were significant positive correlations between the levels of ER and PR for cancer tissue (tau = 0.56, P < 0.005; r(log transform) = 0.68, P < 0.003; n = 17) but not for mucosa, and between levels of ER in cancer tissue and mucosa (tau = 0.55, P < 0.05; r(log transform) = 0.70, P < 0.025; n = 10) but not between the corresponding PR values. In maintenance media, which contained phenol red and unstripped fetal calf serum, the median (range) concentration of ER was 1.9 (1.2-10.4) fmol/mg and that for PR 24.3 (9.1-63.2) fmol/mg in the five cell lines studied (HT-29, LS174T, SW620, LoVo, COLO 320DM). The addition of oestradiol (10 nmol/l) to phenol red-free medium containing 5 per cent dextran-coated charcoal-treated fetal calf serum had little effect on the concentration of ERs or PRs in SW620, LoVo and COLO 320DM cells after 7 days' culture. It is concluded that ERs and PRs are expressed in malignant and normal colonic mucosa. ERs appear to be a feature of the colonic mucosa rather than the malignant process, but in carcinoma may regulate synthesis of PRs, suggesting a degree of oestrogen responsiveness.

Cloning and sequencing of the Escherichia coli panB gene, which encodes ketopantoate hydroxymethyltransferase, and overexpression of the enzyme

The panB gene from Escherichia coli, encoding the first enzyme of the pantothenate biosynthesis pathway, ketopantoate hydroxymethyltransferase (KPHMT), has been isolated by functional complementation of a panB mutant strain with an E. coli genomic library. The gene is 792 bp long, encoding a protein of 264 amino acids with a predicted M(r) of 28,179. The identity of the gene product as ketopantoate hydroxymethyltransferase was confirmed by purification of the enzyme protein, which was overexpressed approximately 50-fold in the mutant harboring the gene on a high-copy-number plasmid. The N-terminal amino acid sequence of the purified protein was found to be identical to that predicted from the gene sequence, as was its mass, determined by electrospray mass spectrometry. Upstream of the panB gene is an incomplete open reading frame encoding a protein of 220 amino acids, which shares sequence similarity to fimbrial precursor proteins from other bacteria. Northern (RNA) analysis showed that the panB gene is likely to be cotranscribed with at least one other gene but that this is not the putative fimbrial protein, since no transcripts for this gene could be detected.

Groin lymphorrhea complicating revascularization involving the femoral vessels

Seven (4%) of 193 patients developed lymphoceles in 8 (2%) of 316 groin wounds after 211 arterial reconstructive procedures. Included were 91 aortic, 15 extra-anatomic, and 105 infrainguinal revascularizations. Lymphoceles developed in otherwise uncomplicated wounds in 6 (8%) of 73 patients with oblique incisions and bilaterally in 1 (1%) of 120 patients with vertical incisions (p = 0.01). This difference may be related to the surgical technique, with increased lymphatic damage and inadequate wound closure in the oblique approach. No increased incidence of lymphorrhea was noted in those patients undergoing aortic reconstruction regardless of the type of incision used (p = 0.15), or when compared with patients who had undergone extra-anatomic or infrainguinal bypass (p = 0.14). Each lymphocele was persistent, and external fistulas spontaneously occurred in three. Diagnosis was based upon clinical awareness and the appearance of the groin mass. Conservative management was uniformly unsuccessful, and operative ablation of the lymph fistula and lymphocele proved to be definitive therapy.

Immunoglobulins from normal sera bind platelet vinculin and talin and their proteolytic fragments

Our previous finding that normal serum immunoglobulins bind to internal platelet proteins on Western blots led us to further identify these proteins and determine the possible significance of autoantibodies against them. A 95-Kd protein reactive with immunoglobulins in most normal sera and easily confused with gpIIIa was shown to be a fragment of vinculin generated by calpain proteolysis. Identity was established by peptide sequencing of the protein purified from platelets stored without specific protease inhibitors. Normal immunoglobulins bound intact vinculin (117 Kd) and metavinculin (152 Kd), and their 105-, 95-, and 80- to 85-Kd proteolytic fragments. IgG in 89%, and IgA and IgM in 100% of normal sera reacted in titers of 10 to 1,000 with purified vinculin. In addition, IgG in 79%, and IgA and IgM in 93% of normal sera reacted in titers of 10 to 5,000 with talin (235 Kd), another cytoskeletal protein, and its 200-Kd proteolytic fragment. IgGs in sera from animals of several different phylogenetic classes also reacted with human vinculin and talin on Western blots. Frequency of occurrence, titers, and classes of antivinculin and antitalin autoantibodies in patients with thrombocytopenia did not differ discernibly from those of normal individuals. These antibodies had no effect on platelet aggregation or clot retraction, and no apparent pathogenic significance, but their widespread presence and the variability in extent of proteolysis of platelet preparations used for Western blots can complicate interpretation of patterns obtained with sera from patients with presumed immune-mediated thrombocytopenias.

Augmented coronary blood flow response to intracoronary norepinephrine after ventricular sympathectomy

BACKGROUND

Ventricular sympathetic denervation may occur as a result of myocardial infarction or heart transplantation. The present study examined the time-dependent effects of surgical ventricular sympathectomy on coronary flow and myocardial contractile responses to intracoronary norepinephrine administration in conscious dogs.

METHODS

Adult mongrel dogs (18-26 kg), were either ventricular sympathectomized or served as a sham-operated control. Animals were studied 2, 4, and 8 weeks after surgery. Measurements of left ventricular systolic pressure (LVSP), maximum rate of left ventricular pressure generation (dP/dtmax), maximum negative rate of segmental shortening (-dL/dtmax), heart rate, and mean circumflex flow velocity (CFV) were obtained before and after bolus administration of norepinephrine into the circumflex artery in doses ranging from 0.01 to 0.50 microgram.

RESULTS

Intracoronary norepinephrine administration caused significant increases in LVSP, dP/dtmax, -dL/dtmax, heart rate, and CFV. After reaching a peak or maximum response, these variables returned to their respective preinjection values, except for CFV, which exhibited a biphasic response. CFV continued to decline below control levels, indicating a vasoconstrictor response to norepinephrine, before returning back to preinjection levels. With the 0.5-microgram dose of intracoronary norepinephrine, the percent increases in CFV were 124% +/- 25% and 105% +/- 15% (P < 0.05) at 2 and 4 weeks respectively, compared with the sham-operated controls, which only increased 56% +/- 15%. The response to the 0.5-microgram dose of norepinephrine at 8 weeks (61% +/- 6%) was not significantly different from control. Elevated myocardial contractile responses in the sympathectomized hearts were also evident at 2 and 4 weeks, but not at 8 weeks. The vasoconstrictor response to norepinephrine administration was not significantly different between sympathectomized and sham-operated hearts. Finally, there was no difference in the change in LVSP, dP/dtmax, or heart rate between any of the groups at any of the doses.

CONCLUSIONS

These results suggest that a supersensitivity to the coronary functional hyperemic response after intracoronary norepinephrine is present in ventricular sympathectomized hearts, but a coronary constrictor supersensitivity does not exist.

Fluoride treatment of osteoporosis: cyclical non-blinded or continuous blinded studies?

The future of sodium fluoride (NaF), the most potent osteoblast stimulator known to man, is in the balance. Of three recent randomized trials of continuous NaF only one found a significant in vertebral fractures in the NaF group. When data from the first year were excluded, two of the studies (those with the largest numbers) showed a significantly reduced risk of vertebral fracture on NaF. The effect of NaF on cortical bone is poorly documented. Two studies have shown reduced forearm cortical bone density with continuous NaF. A further two (histomorphometric) studies have shown the development of increased cortical porosity on continuous NaF treatment. In one, this was selectively at the external cortex and was linearly correlated with cancellous volume increase. Our pilot study using NaF administered cyclically has shown an encouraging (though non-significant) reduction in vertebral fracture rates (excluding year 1) and no fall in forearm cortical density. Another (US) cyclical study has shown no increase in cortical porosity. A current W. Australian randomized study of 50 patients is described where NaF dosage is varied proportional to the osteoblast response, and duration is dependent on densitometric and radiographic response. The future of NaF should involve cyclical administration, in cautious initial dosage (50-60 mg/day) of enteric-coated NaF, in conjunction with a potent inhibitor of resorption such as hormone replacement, bisphosphonates or calcitonin.

Efficacy of the supraclavicular route for temporary hemodialysis access

The percutaneous supraclavicular approach for temporary central venous hemodialysis access was successfully used in 27 of 34 cases (79%) without significant complications and was found to be a durable technique acceptable to every patient. The supraclavicular site was used from 3 to 156 days (mean, 40 days). The average catheter life was 25 days, and 13 guidewire catheter changes among eight patients were required for catheter limb thrombosis or suspected infection. Preventable kinks resulting from technical error occurred in two catheters (5%), necessitating guidewire replacement in one. A total of 41 catheters were used, and infection was documented in one (2%). Catheters were intentionally removed in 21 patients and were removed for proved infection (1) or suspected infection (5) in the remaining six patients. No new clinical evidence of central venous stenosis or thrombosis, such as arm swelling, prominent cutaneous collateral veins, or increased venous pressure at dialysis, was observed. We suggest the supraclavicular approach as the primary route for temporary central venous hemodialysis access. Continued follow-up is necessary to substantiate the initial favorable experience with the supraclavicular technique.

Do graduated compression stockings and pneumatic boots have an additive effect on the peak velocity of venous blood flow?

Graduated compression stockings and intermittent pneumatic compression boots reduce the incidence of deep vein thrombosis. Recent studies suggest that the simultaneous use of these devices may have a synergistic prophylactic effect; however, conflicting reports also exist. Using duplex imaging, we analyzed the effect on peak venous velocity in the superficial femoral vein produced by the individual and simultaneous use of graduated compression stockings and intermittent pneumatic compression boots. Normal volunteers and postoperative patients were examined. The use of intermittent pneumatic compression boots significantly increased the peak venous velocity relative to rest, whereas the use of graduated compression stockings did not alter the peak venous velocity. Also, the addition of graduated compression stockings to legs already being treated with intermittent pneumatic compression boots did not produce a further augmentation of peak venous velocity. This study demonstrates that the simultaneous use of graduated compression stockings and intermittent pneumatic compression boots does not produce a synergistic augmentation of peak venous velocity in the superficial femoral vein.

Effects of a coronary alpha 1-constriction on transmural left ventricular flow and contractile function

Modulation of myocardial contractile function and perfusion by alpha 1-adrenergic receptors were examined in anesthetized dogs during left stellate ganglion stimulation. In 11 dogs, stellate stimulation significantly increased heart rate, mean arterial pressure, left ventricular systolic pressure, maximal rate of left ventricular pressure generation, segmental shortening and rate of shortening in anterior and posterior ventricular regions, and myocardial oxygen extraction. Myocardial lactate extraction decreased. The selective alpha 1-adrenergic antagonist prazosin (0.5 mg) injected into the circumflex artery during stellate stimulation caused significant additional increases in maximal rate of left ventricular pressure generation by 19 +/- 5% and in rate of shortening in posterior subendocardium by 20 +/- 6%. No changes were observed in posterior subepicardial or anterior subendocardial segmental contractile function. Myocardial oxygen and lactate extractions returned to their control values following prazosin injection. Regional left ventricular perfusion was measured using tracer microspheres in five additional dogs. Stellate stimulation increased subepicardial and subendocardial perfusion by 30%. Prazosin increased both subepicardial and subendocardial perfusion by an additional 36%. Stellate stimulation increased norepinephrine concentration in the coronary sinus, but no further increase was noted after blockage of alpha 1-receptors by prazosin. Thus, during sympathetic stimulation, an alpha 1-vasoconstriction existed uniformly across the left ventricular wall. However, blockade of this vasoconstriction was associated with an increase in contractile function only in the deeper muscle layers.

Bile acids influence the growth, oestrogen receptor and oestrogen-regulated proteins of MCF-7 human breast cancer cells

The effects of the major human serum bile acid, glycochenodeoxycholic acid (GCDC), as well as unconjugated chenodeoxycholic acid (CDC), on the MCF-7 human breast cancer cell line have been studied in vitro under oestrogen and bile acid deprived culture conditions. GCDC increased the growth of the breast cancer cells over the range 10-300 microM. At concentrations in excess of the bile acid binding capacity of the medium cell growth was prevented. In contrast 10 microM CDC tended to reduce cell growth. Oestrogen (ER) and progesterone (PgR) receptors, pS2 and total cathepsin D were quantified by monoclonal antibody based immunoassays. Ten to 100 microM GCDC and 10 microM CDC down-regulated ER protein and this was accompanied by induction of the oestrogen-regulated proteins PgR, pS2 and possibly cathepsin D, including increased secretion of the latter two proteins into the culture medium. All these changes were quantitatively similar to those observed with 10 nM oestradiol. The bile acid effects on ER and PgR were not due to interference with the assay procedures. Cells incubated with 50 microM GCDC or 10 microM CDC had higher pmolar concentrations of the bile acids than controls. This study suggests that naturally occurring bile acids influence the growth and steroid receptor function of human breast cancer cells.

Systemic hypoxia activates a coronary vasoconstrictor reflex response that is blocked by prazosin

We assessed the presence of an alpha 1-adrenoceptor-mediated coronary vasoconstrictor reflex response during acute systemic hypoxia in eight chloralose-anesthetized dogs. We avoided local vasodilator responses to myocardial and coronary hypoxia and to circulating factors by perfusing the left common coronary artery at constant pressure with normoxic blood while the dogs were ventilated with 5% O2-95% N2. Left ventricular afterload was held constant by withdrawing arterial blood during hypoxia-induced peripheral vasoconstriction. Left ventricular (LV) preload, as indicated by left atrial pressure, was unchanged. beta-adrenoceptor-mediated coronary dilation and positive chronotropic and inotropic responses to hypoxia were blocked by propranolol. Para-sympathetic-mediated coronary dilation and bradycardia were blocked by atropine. Under these conditions, systemic hypoxia caused a 19.7 +/- 2.1% decrease in left common coronary blood flow. Blockade of left coronary alpha 1-adrenoceptors with prazosin prevented coronary vasoconstriction during repeated systemic hypoxia. In four other similarly prepared dogs, repeated systemic hypoxia without alpha 1-adrenoceptor blockade reproducibly reduced left coronary blood flow 16.3 +/- 3.5 and 15.7 +/- 3.1%, respectively. The results of this investigation provide the first evidence of a coronary vasoconstrictor reflex response to systemic hypoxia. This response is mediated by alpha 1-adrenoceptors.

Comparative hepatotoxicity of two polychlorotrifluoroethylenes (3.1 oils) and two chlorotrifluoroethylene (CTFE) oligomers in male Fischer 344 rats

Polychlorotrifluoroethylene (3.1 oil) is a nonflammable hydraulic fluid composed of chlorotrifluoroethylene (CTFE) oligomers of different carbon chain lengths (C5 to C9), primarily six (trimer) and eight (tetramer) carbons. Four test groups of Fischer 344 rats (16 rats/group) were orally gavaged daily over a 2-week period at doses of 1.25 g/kg with 3.1 oil containing a 55:45 ratio of trimer and tetramer (3.1 oil-C6:C8), 3.1 oil composed of 95% trimer (3.1 oil-C6), pure tetramer, and pure trimer. Four rats per treatment group were terminated after 1, 3, 7, and 14 doses. Rats dosed with either 3.1 oil-C6:C8 or pure tetramer demonstrated significant weight losses, increased liver weights, increased rates of liver fatty acid beta-oxidation, pronounced hepatomegaly and altered hepatocellular architecture, and elevated serum liver-associated enzymes. Rats dosed with either 3.1 oil-C6 or only pure trimer demonstrated significant increase in liver weight and moderate liver histopathologic changes. Compositional analyses of the ratio percentage of trimer to tetramer present in 3.1 oil-C6:C8 (55:45) were found to be altered when measured in the liver (32:68). Differential CTFE oligomer toxicity was indicated by effects on liver, body weight, and peroxisomal beta-oxidation and may allow for less toxic formulations of 3.1 oil to be generated by reducing or eliminating the tetramer component.

An alpha-adrenergic coronary constriction during esophageal distention in the dog

Previous work has shown an increase in sympathetic stimulation of the heart during chemical or mechanical irritation of visceral organs, but the involvement of the coronary circulation in such reflexes is not clear. In five preliminary experiments in anesthetized dogs, esophageal distention produced a sympathetic stimulation of the heart, as evidenced by an increase in heart rate, which was abolished by non-selective beta-adrenergic and muscarinic blockades. On the basis of these preliminary data, we further examined a sympathetic coronary constriction during acute esophageal distension in which any direct adrenergic coronary constriction was unmasked by muscarinic blockade with atropine (100 micrograms/kg, i.v.), and non-selective beta-adrenergic blockade with propranolol (1 mg/kg, i.v.). In seven dogs anesthetized with alpha-chloralose in an open-chest procedure, the esophagus was rapidly distended to a pressure of 36 +/- 2 mm Hg, which was not significantly different from the distending pressure used in the preliminary experiments. During esophageal distention, the mean circumflex blood flow decreased to 77 +/- 10% (SEM) of the predistention value. This decrease was statistically significant (p less than 0.05). There was no change in left ventricular pressure, mean arterial pressure dP/dtmax, or heart rate. Intracoronary administration of the nonselective alpha-adrenergic antagonist phentolamine completely abolished the reduction in mean circumflex coronary blood flow caused by esophageal distention in the presence of beta-adrenergic and muscarinic blockades. These results demonstrate a direct sympathetic coronary vasoconstriction elicited by esophageal distention. This vasoconstriction was due to activation of coronary alpha-adrenergic receptors.