The mechanics of heterotypic cell aggregates: insights from computer simulations

Finite element-based computer simulations are used to investigate a number of phenomena, including tissue engulfment, cell sorting, and checkerboard-pattern formation, exhibited by heterotypic cell aggregates. The simulations show that these phenomena can be driven by a single equivalent force, namely a surface (or interfacial) tension, that results from cytoskeletal components and cell-cell adhesions. They also reveal that tissue engulfment, cell sorting, and checkerboard-pattern formation involve several discernible mechanical features or stages. With the aid of analytical arguments, we identify the conditions necessary for each of these phenomena. These findings are consistent with previous experimental investigations and computer simulations, but pose significant challenges to current theories of cell sorting and tissue engulfment.

The Swedish Two-County Trial twenty years later. Updated mortality results and new insights from long-term follow-up

The benefit of invitation to mammographic screening observed in this trial is maintained as a highly significant 32% reduction in breast cancer mortality. Mammographic screening for breast cancer continues to save lives after up to 20 years. Screening derives this benefit by improving the distribution of tumors diagnosed with respect to prognostic categories based on node status, size, and histology of tumors. There is potential for modern screening programs with shorter interscreening intervals to achieve even greater improvements in prognostic category and greater reductions in breast cancer mortality. Mammography can discriminate a subpopulation of high-risk cases, those displaying casting-type calcifications on the mammogram, among very small tumors, with fundamental implications for diagnosis and treatment.

The mechanics of cell sorting and envelopment

Aggregates of embryonic cells undergo a variety of intriguing processes including sorting by histological type and envelopment of cell masses of one type by another. It has long been held that these processes were driven by differential adhesions, as embodied in the famous differential adhesion hypothesis (DAH). Here, we use analytical mechanics to investigate the forces that are generated by various sub-cellular structures including microfilaments, cell membranes and their associated proteins, and by sources of cell-cell adhesions. We consider how these forces cause the triple junctions between cells to move, and how these motions ultimately give rise to phenomena such as cell sorting and tissue envelopment. The analyses show that, contrary to the widely accepted DAH, differential adhesions alone are unable to drive sorting and envelopment. They show, instead, that these phenomena are driven by the combined effect of several force generators, as embodied in an equivalent surface or interfacial tension. These unconventional findings follow directly from the relevant surface physics and mechanics, and are consistent with well-known cell sorting and envelopment experiments, and with recent computer simulations.

Activation of phospholipase D activity in transforming growth factor-beta-induced cell growth inhibition

Cells regulate phospholipase D (PLD) activity in response to numerous extracellular signals. Here, we investigated the involvement of PLD activity in transforming growth factor-beta (TGF-beta1)-mediated growth inhibition of epithelial cells. TGF-beta1 inhibits the growth of MDCK, Mv1Lu, and A-549 cells. In the presence of 0.4% butanol, TGF-beta1 induces an increase in the formation of phosphatidylbutanol, a unique product catalyzed by PLD. TGF-beta1 also induces an increase in phosphatidic acid (PA) level in A-549 and MDCK cells. TGF-beta1 induces an increase in the levels of DAG labeled with [3H]-myristic acid in A-549 and MDCK cells but not in Mv1Lu cells. No increase of DAG was observed in cells prelabeled with [3H]-arachidonic acid. The data presented suggest that PLD activation is involved in the TGF-beta1-induced cell growth inhibition.

Markov chain models and estimation of absolute progression rates: application to cataract progression in diabetic adults

BACKGROUND

We present a case study in the use of Markov chain models of disease progression, with exponential regression to model the effects of covariates.

METHODS

An exponential regression model was developed for a three-state Markov chain to model progression of cataracts in diabetic patients, with a view to estimation of absolute progression rates. Two methods of estimation were applied, a non-linear least squares approximation, and Markov Chain Monte Carlo (MCMC).

RESULTS

Both methods gave estimated transition rates which can readily be transformed to absolute progression probabilities. Agreement was reasonable for most but not all of the parameters.

CONCLUSIONS

The MCMC estimates had more conservative variance estimates.

2H-Thieno[3,2-e]- and [2,3-e]-1,2-thiazine-6-sulfonamide 1,1-dioxides as ocular hypotensive agents: synthesis, carbonic anhydrase inhibition and evaluation in the rabbit

Novel non-chiral 2H-thieno[3,2-e]- and [2,3-e]-1,2-thiazine-6-sulfonamide 1,1-dioxides were synthesized for evaluation as potential candidates for the treatment of glaucoma. All of the compounds prepared were potent high affinity inhibitors of human carbonic anhydrase II, Ki < 0.5 nM. Additionally, inhibition of recombinant human carbonic anhydrase IV was determined for selected compounds; these were shown to be moderate to potent inhibitors of this isozyme with IC50 values ranging from 4.25 to 73.6 nM. Of the compounds evaluated for their ability to lower intraocular pressure in naturally hypertensive Dutch-belted rabbits, 5a, 17a3, 17b1, 17b2, 17h2 and 17i1 showed significant efficacy (> 20% decrease) in this model following topical ocular administration.

Natriuretic peptides in the pathophysiology of congestive heart failure

A hallmark of congestive heart failure (CHF) is the activation of the cardiac endocrine system, in particular atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). The natriuretic peptides are a group of structurally similar but genetically distinct peptides that have diverse actions in cardiovascular, renal, and endocrine homeostasis. ANP and BNP are of myocardial cell origin and C-type natriuretic peptide (CNP) is of endothelial origin. ANP and BNP bind to the natriuretic peptide-A receptor (NPR-A), which, via 3',5'-cyclic guanosine monophosphate (cGMP), mediates natriuresis, vasodilatation, renin inhibition, antimitogenesis, and lusitropic properties. CNP lacks natriuretic actions but possesses vasodilating and growth inhibiting actions via the guanylyl cyclase-linked natriuretic peptide-B receptor. All three peptides are cleared by the natriuretic peptide-C receptor and degraded by the ectoenzyme neutral endopeptidase 24.11, both of which are widely expressed in kidney, lung, and vascular wall. Recently, a fourth member of the natriuretic peptide, Dendroaspis natriuretic peptide (DNP) has been reported to be present in human plasma and atrial myocardium and is elevated in plasma of human CHF.

RGS7 complex formation and colocalization with the Gbeta5 subunit in the adult rat brain and influence on Gbeta5gamma2-mediated PLCbeta signaling

This study describes the colocalized distribution and dimeric complex formation between RGS7, a GTPase-activating protein for several heterotrimeric Galpha protein families, and the Gbeta5 subunit in the adult rat brain. Confocal dual immunofluorescence labeling studies indicated a broad regional specificity in the cellular coexpression between RGS7 and Gbeta5 within the cerebral cortical layers I and V-VI, hippocampal formation, caudate-putamen, medial habenula, most thalamic nuclei, and cerebellar molecular and granular layers. In all instances, Gbeta1-beta4 immunoreactivities exhibited no observable colocalization with RGS7, despite their widespread codistribution throughout similar neuronal networks. Coimmunoprecipitation studies confirmed the selective protein-protein interaction between RGS7 and Gbeta5 within brain regions that displayed immunohistochemical colocalization. The influence of RGS7 to modulate Gbeta5gamma2-mediated phosphatidyl inositol (PI) production was examined in COS-7-cotransfected cells. In the presence of Gbeta5gamma2 only, intracellular PI accumulation was increased by 25% above basal levels; addition of RGS7 produced no significant alteration in Gbeta5gamma2-mediated PI accumulation. A similar trend was exhibited when full-length RGS7 was substituted with an RGS7 construct lacking the Gbeta5-interacting region (G protein gamma-like domain; GGL domain) or with RGS4. In conclusion, RGS7/Gbeta5 dimers occurred within most brain regions in which both proteins were cellularly coexpressed. However, an influence of RGS7 on Gbeta5gamma2-mediated PLCbeta signaling activity was not apparent, athough this was in COS-7 cell transfection studies.

Body composition in hemodialysis patients--is it different from that of normal subjects?

OBJECTIVE

Body composition assessment is an important method of evaluating nutritional and metabolic status in hemodialysis patients.

PATIENTS AND METHODS

To assess the body composition of hemodialysis patients, we used dual-energy X ray absorptiometry to test 40 stable chronic hemodialysis patients and 40 normal subjects. The patients were from 38 to 70 years old, and all without diabetic mellitus. Comparing with the hemodialysis patients, the normal subjects were selected on a one-to-one base with the same sex and about the same age, body weight and height.

RESULTS

The lean body mass/body weight (LBM/BW) ratio had no significant statistical difference between hemodialysis patients and normal subjects in this study (63.02 +/- 8.42% vs 64.80 +/- 7.92%, p =0.3308). The male LBM/BW ratio was higher than that of the female (71.07 +/- 4.63% vs 59.30 +/- 6.35%, p < 0.0001). According to the multiple linear regression analyses, the LBM of hemodialysis patients had positive correlation with gender (p < 0.0001), height (p = 0.0360) and weight (p < 0.0001). The total bone mineral density (BMD) of hemodialysis patients was found to be lower than that of the normal subjects (0.90 +/- 0.10 g/cm vs 0.97 +/- 0.08 g/cm, p = 0.0092). The BMD had been found to be low in the hemodialysis patients with serum intact parathyroid hormone (iPTH) > 1,700 pg/ml. The BMD had negative correlation with age in the female hemodialysis patients (r = 0.63, p = 0.0009), but no correlation in the male hemodialysis patients and in the female or male normal subjects. With the multiple linear regression analyses, the BMD of hemodialysis patients had positive correlation with weight (p = 0.0329) and negative correlation with age (p = 0.0183) and serum iPTH (p = 0.0231).

CONCLUSION

We concluded that: the LBM/BW ratio of hemodialysis patients was not different from that of normal subjects. Severe secondary hyperparathyroidism hemodialysis patients had low BMD. The BMD had negative correlation with age in the female hemodialysis patients.

A new era in the diagnosis of breast cancer

The regular use of high-quality mammography on asymptomatic women enables most breast cancers to be detected in the preclinical phase. Earlier detection dramatically rearranges the spectrum of breast cancer outcomes, resulting in better control of breast cancer. The new era requires a shift in thinking and a re-evaluation of the traditional diagnostic and therapeutic approaches to breast diseases. Tumors are smaller, less often node-positive, and have a more favorable malignancy grade. The challenge for diagnosticians is to find as many breast cancers as possible in the preclinical phase. The challenge for therapists is to adapt the treatment guidelines accordingly, in order to avoid over-treatment.

In vivo, high-resolution analysis of yeast and mammalian RNA-protein interactions, RNA structure, RNA splicing and ribozyme cleavage by use of terminal transferase-dependent PCR

We have investigated the analysis of RNA by use of terminal transferase-dependent PCR (TDPCR), a procedure previously used for the analysis of DNA and chromatin [J. Komura and A.D.Riggs, Nucleic Acids Res.,26, 1807-1811 (1998)]. When preceded by reverse transcription (RT), TDPCR provides an extremely sensitive, versatile, quantitative and nucleotide-level assay for detecting RNA lesions or structures that block primer extension during the RT step. The procedure is: (i) RT using a gene-specific oligonucleotide; (ii) ribo-tailing of the single-stranded cDNA product by use of terminal deoxy-nucleotidyl transferase; (iii) ligation of a DNA linker to the tailed cDNA by use of T4 DNA ligase; and (iv) PCR using a nested, gene-specific primer and a linker-specific primer. This procedure combines the versatility of a primer extension assay with nucleotide-level resolution, the specificity of nested primers and the sensitivity of PCR. Band patterns obtained are reproducible and quantifiable. We successfully used the technique for the study of yeast RNA structure, splicing intermediates and ribozyme cleavage. Also, in vivo footprint experiments, using mammalian cells and RNase T1, revealed the binding of iron-responsive element binding protein to iron responsive elements in the mRNAs of transferrin receptor and ferritin H-chain.

Molecular cloning and expression of mouse GD1alpha/GT1aalpha/GQ1balpha synthase (ST6GalNAc VI) gene

A novel member of the mouse CMP-NeuAc:beta-N-acetylgalactosaminide alpha2,6-sialyltransferase (ST6GalNAc) subfamily, designated ST6GalNAc VI, was identified by BLAST analysis of expressed sequence tags. The sequence of the cDNA clone of ST6GalNAc VI encoded a type II membrane protein with 43 amino acids composing the cytoplasmic domain, 21 amino acids composing the transmembrane region, and 269 amino acids composing the catalytic domain. The predicted amino acid sequence showed homology to the previously cloned ST6GalNAc III, IV, and V, with common amino acid sequences in sialyl motif L and S among these four enzymes. A fusion protein with protein A and extracts from L cells transfected with ST6GalNAc VI in an expression vector showed enzyme activity of alpha2,6-sialyltransferase for GM1b, GT1b, and GD1a but not toward glycoproteins. Thin layer chromatography-immunostaining revealed that the products were GD1alpha, GQ1balpha, and GT1aalpha. Northern blotting revealed that this gene was expressed in a wide range of mouse tissues such as colon, liver, heart, spleen, and brain. It is concluded that this enzyme is a novel sialyltransferase involved in the synthesis of alpha-series gangliosides in the nervous tissues and many other tissues.

The modulating actions of sulfonylurea on atrial natriuretic peptide release in experimental acute heart failure

OBJECTIVES

This study defined the modulating actions of sulfonylurea on acute release of atrial natriuretic peptide (ANP) in experimental acute heart failure.

BACKGROUND

Sulfonylurea drugs, blockers of cardioprotective ATP-sensitive K(+) (K(ATP)) channels, may increase the risk of early cardiovascular mortality. In cardiovascular diseases such as acute heart failure, early release of ANP is essential for cardiorenal homeostasis. Although K(ATP) channels regulate secretion of hormones, such as insulin, it is unknown whether sulfonylureas interfere with ANP release in acute heart failure.

METHODS

The effects of acute administration of glyburide (0.3 mg/kg), a prototype sulfonylurea, on ANP release and sodium excretion were measured in vivo in a canine model of pacing-induced acute heart failure characterized by acute atrial stretch. Immunoreactivity, in atrial tissue, for ANP and the K(ATP) channel subunit, Kir6.2, was determined using specific antibodies.

RESULTS

With increased left atrial pressure in heart failure, plasma levels of ANP increased rapidly and peaked within 25+/-3 min. Glyburide delayed the time required for peak plasma ANP secretion to 48+/-5 min. This resulted in reduced natriuresis from 84+/-17 microEq/min in the absence of glyburide, to 34+/-9 microEq/min in the presence of glyburide. However, glyburide did not alter the renal natriuretic responsiveness to exogenously administered ANP in normal dogs. In atrial tissue, both ANP and the K(ATP) channel subunit, Kir6.2, displayed strong immunoreactivity and co-localization.

CONCLUSIONS

Glyburide delays release of ANP in acute heart failure resulting in impaired natriuresis. This cannot be ascribed to an antinatriuretic effect on the kidney, but rather may be due to interference with K(ATP) channel-dependent ANP secretion from the atrium. Such adverse outcome of sulfonylurea drug use could reduce the compensatory capacity to preserve cardiorenal homeostasis in acute heart failure.

Vascular actions of brain natriuretic peptide: modulation by atherosclerosis and neutral endopeptidase inhibition

OBJECTIVES

We sought to define the vascular actions of the cardiac hormone brain natriuretic peptide (BNP) on cellular proliferation and cyclic guanosine monophosphate (cGMP) in human aortic vascular smooth muscle cells (HAVSMCs). Secondly, we investigated BNP and acetylcholine (ACh) vasorelaxations in aortic rings from normal and atherosclerotic rabbits in the presence and absence of long-term oral inhibition of neutral endopeptidase (NEP).

BACKGROUND

The vascular actions of BNP are not well defined, despite the presence of its receptor in vascular smooth muscle and the upregulation of NEP, the ectoenzyme that degrades BNP, in the vascular wall in atherosclerosis.

METHODS

HAVSMCs stimulated with fetal calf serum (FCS) were pulsed with bromodeoxyuridine (BrdU) with and without BNP. The HAVSMCs were incubated in the presence and absence of BNP to assess cGMP. Vasorelaxations to BNP and ACh were assessed in rings in normal and atherosclerotic rabbits in the presence and absence of long-term oral inhibition of NEP, together with assessment of atheroma formation.

RESULTS

FCS-stimulated BrdU uptake in HAVSMCs was suppressed with BNP. BNP potentiated cGMP in HAVSMCs. BNP resulted in potent vasorelaxation in normal isolated aortic rings, which were impaired in atherosclerotic versus normal rabbits and preserved with NEP inhibition, which also decreased atheroma formation. Relaxations to ACh, which were also impaired in atherosclerosis, were preserved with inhibition of NEP.

CONCLUSIONS

We conclude that BNP potently inhibits vascular smooth muscle cell proliferation and potentiates the generation of cGMP. BNP potently relaxes the normal rabbit aorta, and this response is impaired in atherosclerosis but preserved with inhibition of NEP, together with a reduction in atheroma formation and preservation of relaxations to ACh.

A novel method for prediction of long-term outcome of women with T1a, T1b, and 10-14 mm invasive breast cancers: a prospective study

BACKGROUND

Women with small mammographically detected breast cancers generally have good long-term outcomes, but a few with T1a (1-5 mm) and T1b (6-10 mm) tumours will eventually die from breast cancer. We investigated whether women at high risk of breast-cancer death could be identified with mammographic criteria and differentiated from women with small cancers of the breast and good outcomes.

METHODS

We prospectively applied mammographic classifications of tumour type to a consecutive series of 343 mammograms of invasive breast cancers of size 1-14 mm. Classifications were: stellate (spiculated) mass with no calcifications; circular or oval lesions with no calcifications; spiculated or circular lesions with non-casting-type calcifications; and casting-type calcifications.

FINDINGS

20-year survival for women with 1-14 mm invasive tumours with casting-type calcifications was 55%. 14% of 138 women with 1-9 mm tumours had casting-type calcifications on mammography, which accounted for 73% of all breast-cancer deaths (p<0.001). T1a, T1b, and 10-14 mm tumours with casting-type calcifications behaved as if they were larger lesions, since the rate of death was similar to that for women with advanced high-grade tumours. Most women who died were node-negative. The long-term survival of women who had tumours of 1-9 mm with no casting-type calcifications was about 95%.

INTERPRETATION

Mammographic classification seemed to reliably predict good and bad long-term outcomes for survival in tumours of 14 mm or smaller, and especially for those smaller than 10 mm. The implications for therapy are substantial.

Factors affecting the first recurrence of noncardioembolic ischemic stroke

Studies of the factors affecting the first recurrence of ischemic stroke have reported inconsistent findings. Types of initial stroke and the racial differences in study samples are among the explanations that may account for this inconsistency. The aims of this study were to estimate the cumulative recurrence rates of noncardioembolic ischemic stroke and identify the factors that influence the first recurrence of noncardioembolic ischemic stroke in the Taiwanese Chinese population. Four hundred and sixty-six patients with noncardioembolic ischemic stroke from thirteen hospitals in Taiwan were followed up in this study to ascertain first recurrence of noncardioembolic ischemic stroke between October 1992 and April 1995. The Kaplan-Meier method was used to estimate the cumulative recurrence rate. The Cox regression model was used to ascertain the significant factors affecting the first recurrence of noncardioembolic ischemic stroke. The overall cumulative recurrence rate was 10.5% (49/466) from the follow-up period of 30 months. After adjustment for age, sex, treatment modes, and variables pertinent to blood pressure, the site of brain lesion remained a significant factor. The relative risk of first recurrence for the basal ganglion vs. the region of middle cerebral artery was 3.06 (95% CI: 1.29-7.26). The brain lesion site was demonstrated to be an independent predictor of risk for the first recurrence of noncardioembolic ischemic stroke among the Taiwanese Chinese population. Whether this finding was also seen in other populations should be corroborated in future research.

Alpha-tocopherol downregulates the expression of GPIIb promoter in HEL cells

Alpha-tocopherol is known to inhibit platelet aggregation but the mechanism responsible for this has not been elucidated. Glycoprotein IIb (GPIIb) is the alpha-subunit of the platelet membrane protein GPIIb/IIIa, which functions as a specific receptor for platelet aggregation. Human erythroleukemia (HEL) cells are megakaryocytelike and express the megakaryocyte-specific GPIIb gene. To understand the molecular mechanism of alpha-tocopherol on antiaggregation, we analyzed the effect of physiologically relevant concentrations of alpha-tocopherol on the expression of human GPIIb promoter in HEL cells. The enhancement of tetradecanoylphoerbol-12,13-acetate (TPA)-mediated transient and optimal expression of plasmids was achieved by adding 10(-7)-M TPA in the medium 24 h before lipofection. Transient expression of GPIIb promoter was determined in transfected cells pretreated with various concentrations of alpha-tocopherol. Our data shows that the GPIIb promoter activity was downregulated to 55, 23, 27, 20, and 15% in the presence of 10, 20, 40, 80, and 120 microg/ml of alpha-tocopherol, respectively, as compared with that in the absence of alpha-tocopherol. The downregulation of alpha-tocopherol on the TPA-mediated GPIIb promoter activity may result in a reduction of GPIIb protein expression and thus contribute to antiplatelet aggregation.

Laparoscopic colectomy compares favorably with colectomy by laparotomy for reduction of postoperative ileus

PURPOSE

The aim of this study was to compare the length of postoperative ileus in patients undergoing colectomy by either laparotomy or laparoscopy.

METHODS

A total of 166 patients were studied. These patients were divided into two groups: Group 1, in which colectomy was done laparoscopically, and Group 2, consisting of patients undergoing laparotomy. Both groups contained 83 patients who were matched for disease severity, indications for surgery, and procedure. Indications for surgery included sigmoid diverticulitis in 12 (14 percent) patients, polyps in 22 (27 percent), Crohn's disease in 21 (25 percent), colorectal cancer in 11 (13 percent), stoma reversal in 8 (10 percent), rectal prolapse in 3 (4 percent), and other indications in 6 (7 percent) in each group. Operations were colectomy with anastomosis (42 ileocolic, 26 colorectal, 6 colocolic, 4 ileorectal, and 2 ileal J pouch) or without anastomosis (3 abdominoperineal resections) performed by the same surgeons during the same time period January 1993 to October 1996). The nasogastric tube was removed from all patients immediately after surgery in both groups. All patients received a clear liquid diet on the first postoperative day, followed by a regular diet as tolerated. The nasogastric tube was reinserted if two or more episodes of emesis of more than 200 ml occurred in the absence of bowel movement. Patients were discharged from the hospital when tolerating a regular diet without evidence of ileus. Statistical analysis was performed using unpaired t-test and Fisher's exact probability test.

RESULTS

The male-to-female ratio was 38 to 45 in both groups. A total of 10 (12 percent) and 23 (28 percent) patients in Group 1 and Group 2 had emesis (P = 0.02), and the rate of nasogastric tube reinsertion was 5 (6 percent) and 13 (16 percent), respectively (P > 0.05). There were significant differences between Groups 1 and 2 relative to the lengths of ileus (3.5 +/- 1.3 vs. 5.4 +/- 1.7 days, respectively; P < 0.001), hospitalization (6.6 +/- 3.3 vs. 8.1 +/- 2.5 days, respectively; P < 0.002), and operative time (170 +/- 60 vs. 114 +/- 46 minutes, respectively; P < 0.001). The morbidity rate was 16 (19.2 percent) and 18 (21.6 percent) in the laparoscopy and laparotomy groups, respectively.

CONCLUSIONS

Although early oral intake is safe and can be tolerated by 84 percent of patients after colectomy by laparotomy, laparoscopic colectomy reduced the lengths of both postoperative ileus and hospitalization.

Some random-effects models for the analysis of matched-cluster randomised trials: application to the Swedish two-county trial of breast-cancer screening

BACKGROUND

In the Swedish two-county trial women aged 40-74 years from two counties in Sweden were randomised to invitation to mammographic screening for breast cancer.

METHODS

This paper uses random effects logistic regression models to analyse recent data from the trial. The analysis accounts for the structure of the trial, where small geographical units are randomised within larger geographical strata (blocks of two or three small units that are socio-economically similar).

RESULTS

Fixed effects and a variety of random effects models show a strong degree of agreement and yield a significant 29% or 30% reduction in breast-cancer mortality.

DISCUSSION

Fixed effects and random effects models agree for this example, because heterogeneity both between strata and within strata between clusters is small and because the effect of treatment does not vary much in different strata.

The versatile anterolateral thigh flap: a musculocutaneous flap in disguise in head and neck reconstruction

In search of an alternative soft tissue free flap donor site to radial forearm flap and rectus abdominis flap in head and neck reconstruction, we used the anterolateral thigh flap for reconstruction of various defects in the head and neck in 59 patients. The aim was to demonstrate the versatility of this donor site and propose a new approach to achieve a safer flap dissection. With the exception of three cases, all defects resulted from excision of malignant tumours. The defects were categorised as full thickness defects of the mandible (33.9%), full thickness defects of the cheek (52.5%) and others (13.6%). During the flap dissection a direct septocutaneous pedicle was observed in 12% of the cases. In the remaining cases there were only musculocutaneous perforators and the flaps were raised either as a split vastus lateralis musculocutaneous flap (72%) or as a perforator flap (16%), depending on the required thickness. Total flap survival was 96.7% with one total and one partial failure and two re-explorations (3.3%). The mean follow-up time was 7.1 months (range: 1-12 months). In conclusion, the anterolateral thigh flap is a versatile and dependable flap that can be adapted to any type of defect by modifying the flap design and composition. It should be considered to be a musculocutaneous flap of the vastus lateralis muscle that can also be raised as a perforator flap. When harvested and used in this context, the flap dissection becomes very safe and consistent, nullifying the only major disadvantage associated with this donor site.

Renal response to acute neutral endopeptidase inhibition in mild and severe experimental heart failure

BACKGROUND

Neutral endopeptidase 24.11 (NEP) is a metalloprotease that is localized in the greatest abundance in the kidney and degrades natriuretic peptides, such as atrial natriuretic peptide (ANP). Mild congestive heart failure (CHF) is characterized by increases in circulating ANP without activation of the renin-angiotensin-aldosterone system (RAAS) or sodium retention. In contrast, severe CHF is characterized by sodium retention and coactivation of both ANP and the RAAS.

METHODS AND RESULTS

We defined the acute cardiorenal actions of the NEP inhibitor candoxatrilat (8 microg. kg(-1). min(-1)) in 4 groups of anesthetized dogs (normal, n=8; mild CHF, n=6; severe CHF, n=5; and severe CHF with chronic AT(1) receptor antagonism, n=5). Mild CHF was produced by rapid ventricular pacing at 180 bpm for 10 days and severe CHF at 245 bpm for 10 days. In mild CHF, urinary sodium excretion and glomerular filtration rate were greatest in response to acute NEP inhibition compared with the response in either control animals or those with severe CHF. Furthermore, an increase in glomerular filtration rate was observed only in mild CHF in association with increases in renal blood flow and decreases in renal vascular resistance and distal tubular sodium reabsorption. Urinary ANP and cGMP excretion, markers for renal biological actions of ANP, were greatest in mild CHF. The renal actions observed in mild CHF were attenuated in severe CHF and not restored by chronic AT(1) receptor antagonism.

CONCLUSIONS

The results of the present study demonstrate that acute NEP inhibition in mild CHF results in marked increases in renal hemodynamics and sodium excretion that exceed that observed in control animals and severe CHF. These studies underscore the potential therapeutic role for NEP inhibition to enhance renal function in mild CHF, an important phase of CHF that is marked by selective activation of endogenous ANP in the absence of an activated RAAS.

Laparoscopic colectomy is superior to laparotomy for reduction of disability in patients with colorectal adenoma

BACKGROUND

This study was to evaluate disability after laparoscopic colectomy in patients with colorectal adenomas as compared to disability after laparotomy.

METHODS

Patients who underwent laparoscopic colectomy for colorectal adenoma were compared to patients who underwent laparotomy for the same problem by the same surgeons during the same time period in Cleveland Clinic Florida. A standard questionnaire was used to assess disability which included the number of days to return to partial activity, full activity, and work.

RESULTS

Twenty-nine patients who underwent laparoscopy were compared with 31 patients who underwent laparotomy. There were no significant differences in age (70.4 vs 72.5 years) (p = 0.405) or gender (M:F 13:16 vs 20:11) (p = 0.126) between the laparoscopy and laparotomy groups. The operative time was longer for the laparoscopy group than the laparotomy group: 170 vs 131 minutes (p = 0.014). However, the duration of postoperative ileus, hospitalization, time until return to partial activity, time until return to full activity, and time off of work were significantly shorter in the laparoscopy group than in the laparotomy group: 3.3 vs 5.2 days, 6.2 vs 8.7 days, 2.3 vs 4.2 weeks, 4.4 vs 9.3 weeks, and 3.7 vs 7.3 weeks, respectively (p < 0.041 for all). Although the incidence of postoperative complications was not significantly different (24% for laparoscopy vs 29% for laparotomy, p = 0.325), the incidence of postoperative prolonged ileus was statistically significantly lower in the laparoscopy group (3% vs 26%, p = 0.027).

CONCLUSION

Laparoscopic colectomy for patients with colorectal adenoma can reduce postoperative ileus, postoperative hospitalization, and disability in terms of a quicker return to partial activity, full activity, and employment. Laparoscopic colectomy should be considered for all patients who have colorectal adenomas which require resection.

Primary and adjuvant therapy, prognostic factors and survival in 1053 breast cancers diagnosed in a trial of mammography screening

BACKGROUND

As mammographic screening becomes more widespread, larger numbers of tumours are diagnosed while small and node negative.

METHODS

We examined detection mode, tumour size, node status, histological type, therapy and outcome in 1053 breast cancers diagnosed in one county of the Swedish Two-County Trial of mammographic screening for breast cancer.

RESULTS

Of patients undergoing total mastectomy with axillary dissection, 65% were found to be node negative. For tumours of size 1-9 mm, 95% were node negative. The major effects on survival were tumour size, node status and histological type. Primary adjuvant therapy had no significant association with survival.

CONCLUSIONS

The advent of mammography has substantially enhanced the possibilities for less radical treatment. There is an urgent need for therapeutic trials utilizing mammographic-pathological correlations to ascertain in advance which tumours can and which cannot benefit from more radical therapy.

Clinicopathologic and cytologic features of a metanephric adenoma of the kidney: a case report

Metanephric adenoma is a recently described rare and benign renal neoplasm. Our patient, a 37-year-old woman, suffered from flank pain for five months and was found to have a renal mass. Ultrasound, computerized tomography and angiography findings were consistent with a hypovascular renal cyst. Wilms' tumor was the initial misdiagnosis, based on needle biopsy and aspiration cytology. A radical nephrectomy was performed. Histologically, the tumor was well defined and was composed of uniform small cells arranged in a solid, tubular or rosette-like pattern. The prognosis is good for metanephric adenoma. The tumor was first considered a benign counterpart of papillary carcinoma or Wilms' tumor; however, recent cytogenetic evidence suggested that the tumor might be related to papillary adenoma and papillary renal cell carcinoma. The clinical, radiologic, histologic and cytologic features presented here should help to promote the correct preoperative diagnosis and to avoid unnecessary aggressive treatment.