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Biomedical subjects

C Rossetti

Publications and source records attributed to C Rossetti.

At least 55 records · Page 3Linked to original sources
PubMed1992

Double versus single stapling technique in rectal anastomosis.

A retrospective analysis to compare the single vs double stapled technique for rectal anastomosis was carried out on patients that underwent radical surgical resection between January 1986 and January 1989 at the Istituto Nazionale Tumori of Milan. In 143 patients anastomotic integrity had been checked both intraoperatively with air insufflation and postoperatively by water soluble contrast enema. A single stapled anastomosis (SST) was performed using the EEA instrument in 94 patients, and in 49 patients a double stapled (DST) using the EEA and TA instruments was performed. The level of the anastomosis was less than or equal to 10 cm from the anal margin in 94 patients (54 SST, 40 DST). In 52 patients it was greater than 10 cm (40 SST, 12 DST) (SST vs DST ns). The presence of anastomotic dehiscence occurred in 29 (20%) patients (17 SST, 12 DST). This was not related either to the anastomotic site or to the suture technique used. The dehiscence was located on the posterior wall in 79% of cases and in 58% the size was less than 1 cm. In 78% clinical symptoms were evident. There was no difference between SST and DST patients. Further surgery (colostomy) was necessary in six patients (2 SST, 4 DST). Two patients died through complications (1 SST, 1 DST); making an overall mortality rate of 1.0% and 2.0% in each group. There was no difference in infection rate and length of postoperative stay in the two groups. Our data demonstrate that both methods give similar results.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1991

Three-step monoclonal antibody tumor targeting in carcinoembryonic antigen-positive patients.

We describe a method to postlabel, in vivo, biotinylated monoclonal antibodies pretargeted onto tumor deposits when most of the non-tumor-bound antibodies have already been cleared as avidin-bound complexes. The application of this principle to tumor detection by immunoscintigraphy was tested in 20 patients with histologically documented cancer and increased circulating carcinoembryonic antigen levels. One mg of biotinylated anti-carcinoembryonic antigen monoclonal antibody (FO23C5) was administered i.v. (first step). After 3 days, 4-6 mg of cold avidin were injected i.v. (second step), followed 48 h later by 0.2-0.3 mg of a biotin derivative labeled with 111In (2-3 mCi) (third step). No evidence of toxicity was observed. Whole body radioactivity distribution was measured in five patients at various intervals postinjection by the conjugate counting technique. Tumors and metastases were detected in 18 of 19 patients (the remaining patient was a true negative) within 3 h after administration of 111In-biotin by planar or single photon emission tomography imaging. At the time of imaging, tumor/blood pool ratio was 5.5 +/- 3.2, and tumor/liver ratio was 6.7 +/- 3.9. Blood clearance of 111In-biotin was multiexponential, with the fast component having a t1/2 of 5 +/- 3 min. Urinary excretion of radioactivity over 3 h was 63.5 +/- 4.9% of the injected dose. Radioactivity at 3 h was 6.5 +/- 1.8% in blood, 1.6 +/- 0.3% in the kidney, and 2.4 +/- 0.6% in the liver. This approach represents an improvement in immunoscintigraphic techniques for tumor localization. The potential use for radioimmunotherapy is discussed.

Antibodies, Monoclonal↗
PubMed1991

Active transport of polypeptides in rabbit nasal mucosa: possible role in the sampling of potential antigens.

Transepithelial pathways of macromolecule transport have been studied in vitro in rabbit nasal respiratory mucosa, maintained at 27 degrees C. Transepithelial electrical potential difference, short-circuit current and resistance were 3.4 +/- 0.5 mV (submucosa positive), 65.0 +/- 6.7 microA cm-2 and 52.1 +/- 5.6 omega cm-2 respectively (n = 15). These electrical characteristics are those of a leaky epithelium allowing macromolecules to permeate paracellularly. A detailed permeation study of a polypeptide (elcatonin, Mw = 3362) was also undertaken. Elcatonin mucosa-submucosa (Jms) and submucosa-mucosa (Jsm) fluxes were measured by radioimmunoassay. With 10 micrograms/ml elcatonin, Jms was significantly larger than Jsm for the whole 120-min period of observation; net flux showed a maximum in the first 30 min (Jms = 13.6 +/- 1.0 ng cm-2 h-1, Jsm = 1.4 +/- 0.1 ng cm-2 h-1, n = 10). Jms fell towards the value of Jsm if the temperature was reduced to 4 degrees C or if the mucosa was simultaneously treated with 0.1 mM dinitrophenol and 3 mM monoiodoacetate. Jms and Jnet followed saturation kinetics with increasing elcatonin concentrations. Adrenocorticotropic hormone (Mr = 4500) produced a similar pattern to elcatonin. However, Jms and Jsm were not significantly different from each other at any time either for [3H]sucrose (Mw = 342) or for [14C]polyethyleneglycol-4000 (Mw = 4000) when present in the bathing medium at 500 microM concentration. The results show active transport of polypeptides in parallel with passive permeation (possibly through leaky intercellular junctions). Active transport does not appear to be related to nonspecific pinocytosis but to receptor-mediated endocytosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1991

Transepithelial electrophysiological parameters in rabbit respiratory nasal mucosa isolated in vitro.

1. Transepithelial electrical p.d. (Vms), short circuit current (Isc) and transepithelial resistance (Rep) were determined in rabbit nasal mucosa and were compared with the equivalent parameters of human nasal mucosa. 2. Vms was about 1 mV (submucosa positive) in the absence of glucose, but increased continuously in the presence of glucose. Since Isc also increased in parallel and Rep remained constant (about 40 omega cm2), glucose effect was to power pumping. 3. Diffusion potentials raised by reducing luminal Cl- or Na+ or Cl- and Na+ concentrations were also measured and compared with values obtained in trachea and gallbladder. 4. Evidence is produced, with sounder basis than in trachea, that junctional pathways in airway epithelia are lined with fixed positive charges (which make anions more permeable than cations), unlike junctional pathways of the gastrointestinal tract which are lined with fixed negative charges.

Animals↗
PubMed1990

In vivo metabolism and kinetics of 99mTc-HMPAO.

The cerebral distribution of 99mTc-labeled d, l, hexamethyl-propylene-amine-oxime (99mTc-HMPAO) as a function of rCBF and time was examined in rats and in man. The results of this study confirm that 99mTc-HMPAO is distributed in brain in proportion to rCBF. However, the rapid systemic breakdown of the tracer in blood results in considerable difficulties in the assessment of the arterial concentration of the parent compound; incomplete extraction of 99mTc-HMPAO from blood to brain and significant efflux from brain represent further limitations in the use of this tracer for quantification of rCFB. Despite these limitations 99mTc-HMPAO is of potential interest for a qualitative assessment of rCBF in specific clinical conditions.

Animals↗
PubMed1990

The nature of the neutral Na(+)-Cl- coupled entry at the apical membrane of rabbit gallbladder epithelium: III. Analysis of transports on membrane vesicles.

In rabbit gallbladder epithelium, a Na+/H+, Cl-/HCO3- double exchange and a Na(+)-Cl- symport are both present, but experiments on intact tissue cannot resolve whether the two transport systems operate simultaneously. Thus, isolated apical plasma membrane vesicles were prepared. After preloading with Na+, injection into a sodium-free medium caused a stable intravesicular acidification (monitored with the acridine orange fluorescence quenching method) that was reversed by Na+ addition to the external solution. Although to a lesser extent, acidification took place also in experiments with an electric potential difference (PD) equal to 0. If a preset pH difference (delta pH) was imposed [( H+]in greater than [H+]out, PD = 0), the addition of Na-gluconate to the external solution caused delta pH dissipation at a rate that followed saturation kinetics. Amiloride (10(-4) M) reduced the delta pH dissipation rate. Taken together, these data indicate the presence of Na+ and H+ conductances in addition to an amiloride-sensitive, electroneutral Na+/H+ exchange. An inwardly directed [Cl-] gradient (PD = 0) did not induce intravesicular acidification. Therefore, in this preparation, there was no evidence for the presence of a Cl-/OH- exchange. When both [Na+] and [Cl-] gradients (outwardly directed, PD = 0) were present, fluorescence quenching reached a maximum 20-30 sec after vesicle injection and then quickly decreased. The decrease was not observed in the presence of a [Na+] gradient alone or the same [Na+] gradient with Cl- at equal concentrations at both sides. Similarly, the decrease was abolished in the presence of both Na+ and Cl- concentration gradients and hydrochlorothiazide (5 x 10(-4) M). The decrease was not influenced by an inhibitor of Cl-/OH- exchange (10(-4) M furosemide) or of Na(+)-K(+)-2Cl- symport (10(-5) M bumetanide). We conclude that a Na+/H+ exchange and a Na(+)-Cl- symport are present and act simultaneously. This suggests that in intact tissue the Na(+)-Cl- symport is also likely to work in parallel with the Na+/H+ exchange and does not represent an induced homeostatic reaction of the epithelium when Na+/H+ exchange is inhibited.

Amiloride↗
PubMed1990

Chloride conductance and intracellular chloride accumulation in mouse Peyer's patch enterocytes.

1. Measurements of membrane potential, Cl- conductance and intracellular Cl-, K+, Na+ and H+ activities have been carried out in the follicle-associated epithelium of the mouse Peyer's patch to characterize further the physiological properties of antigen-transporting M cells, enterocytes and intraepithelial lymphocytes. 2. Intraepithelial lymphocytes, identified in random impalements as a second negative jump in membrane potential (Vm), were found to have higher K+ and H+ activities, lower Na+ and Cl- activities and higher negative values for Vm than either of the other two epithelial cell types. Cl- activity in these cells was higher than that predicted from the Nernst equation. 3. M cells identified as having the first negative jump in Vm in impalements involving intraepithelial lymphocytes were unable to accumulate Cl-. They also had a lower Vm than that found in apparently fully differentiated enterocytes. This Vm was partly depolarized at a low Cl- concentration. 4. Apparently fully differentiated enterocytes could be further divided into two populations depending on whether the Vm could or could not be partly depolarized by a low Cl- concentration. The mean Vm and intracellular Cl- activity of Cl(-)-sensitive cells, measured in high Cl- medium, were less than values found for Cl(-)-insensitive enterocytes. Cl- was only accumulated by enterocytes showing no depolarization at low external Cl- concentration. 5. The Vm of mature villus enterocytes was the same as that determined for Cl(-)-insensitive follicle-associated enterocytes. Villus enterocyte Vm was not depolarized at a low Cl- concentration. 6. The present ability to distinguish two apparently large populations of follicle-associated enterocytes having M cell-like or villus enterocyte-like properties is discussed in relation to current theories describing how M cells might be formed. The presence of a Cl- conductance in M cell enterocytes, the inability to accumulate Cl- and the maintenance of a low Vm could aid endocytosis of macromolecules across the apical membrane.

Animals↗
PubMed1990

Brush-border membrane alkaline phosphatase activity in mouse Peyer's patch follicle-associated enterocytes.

1. Using a new method of quantitative cytochemistry to determine alkaline phosphatase activity, it was possible to identify M cells and distinguish two further types of enterocytes present in mouse Peyer's patch follicle-associated epithelial tissue. 2. A quantitative description of these three cell types was provided by making direct absorbance measurements of enzyme reaction product on the luminal surface of individual follicle-associated enterocytes. M cells having a negligible alkaline phosphatase activity had a mean absorbance of 6 +/- 2 arbitrary units. The other two populations of enterocytes had overlapping but significantly different mean absorbances of 20 +/- 2 and 30 +/- 3 arbitrary units. 3. M cells accounted for 3.2 +/- 1% of the total number of cells present in the apical part of the follicle-associated epithelium. This percentage is a minimum value describing an extreme example of cells having M cell-like characteristics. The remaining epithelial cells were divided equally between those having high and low alkaline phosphatase activities in their brush-border membranes. A small percentage of cells having low alkaline phosphatase activities could perform M cell functions. 4. Results obtained suggest that reduced alkaline phosphatase activity and brush-border membrane Cl- conductance can both be used as differentiation markers to identify a large population of poorly differentiated enterocytes present in mouse follicle-associated epithelial tissue.

Alkaline Phosphatase↗
PubMed1990

Measurement with microelectrodes of intracellular Na+, K+, H+ and Cl- activities and of membrane potential in normal rat liver slices and during the 4-dimethylaminoazobenzene-induced rat hepatocarcinogenesis.

Steady-state membrane potentials (Vm) and intracellular Na+ (aiNa), K+ (aiK), H+ (aiH) and Cl- (aiCl) activities were measured with double-barrelled ion-selective microelectrodes in liver slices from normal rats and during the 4-dimethylaminoazobenzene-induced (DAB) hepatocarcinogenesis. Rats fed with the experimental regimen without the carcinogen were used as control animals. In Krebs-Henseleit bicarbonate saline containing 5.5 mM glucose as bathing solution at 37 degrees C, Vm was found to be significantly lower in neoplastic hepatocytes, compared to normal liver cells. Vm decreased also in control rat liver cells. Increased Na+/K+ ratios and Na+ + K+ activities were found in cancerous hepatocytes whereas H+ and Cl- activities decreased. Therefore, the intracellular pH increased significantly in neoplastic cells, compared to normal and control cells. This could reflect activation of the Na+/H+ exchange system during the DAB-induced hepatocarcinogenesis, leading to a stimulation of cell metabolism with increased rate of protein and DNA synthesis and loss of growth control, under these conditions.

Animals↗
PubMed1989

Enterocyte-lymphocyte interactions in the follicle-associated epithelium of the mouse Peyer's patch.

1. Measurements of membrane potential (Vm) have been carried out in the follicle-associated epithelium of the mouse Peyer's patch to investigate possible site-dependent anomalies in enterocyte development. Initial heterogeneity in Vm values obtained from carrying out random impalements in the upper third of the follicle-associated epithelium could be described as arising from the presence of three different cell populations. 2. The predominant cell type in this epithelium (T1) had a mean Vm of -35.3 mV which was partly depolarized by increasing concentrations of K+. These cells were not stained with the vital dye Neutral Red. Two other types of cell (T2L and T2H) were recorded together as consecutive negative jumps in Vm, but only in areas of the epithelium previously stained with Neutral Red. T2L behaved like T1 cells to K+ but with a low Vm of -23.3 mV. T2H cells had a high mean Vm of -47.5 mV showing transient hyperpolarization to increasing K+ concentration. 3. The electrophysiological and non-staining properties of T1 cells are similar to those expected from mature enterocytes. The anatomical size, site, staining properties and Vm of T2H cells correspond to those expected for intraepithelial lymphocytes. The low Vm, K+ depolarization and close association of T2L with T2H cells are typical of properties predicted for an immature-type of antigen-transporting enterocyte known to be present in this type of epithelium. 4. The possibility that intraepithelial lymphocytes either slow or reverse a more normal process of development of enterocytes in their immediate vicinity is discussed along with wider aspects of enterocyte-lymphocyte interactions leading to the transfer to enteric antigens across these modified cells.

Animals↗
PubMed1989

Enkephalin regulation of L-valine transport in rabbit ileum.

We studied the influence on ionic basal transport (Na+ and Cl-) and L-valine transport of two enkephalins which are not metabolized and act in delta and mu receptors respectively. Transports have been indirectly determined measuring the transepithelial electric potential and the short circuit current. DADLE does not significantly influence ion and amino-acid transport, while DAGO alters both of them in the presence of the myenteric plexus (muscle layers present) or inhibits only L-valine transport in the absence of the plexus (muscle layers removed).

Animals↗
PubMed1988

Abnormal pattern of mucin secretion at the resection margin of colorectal carcinomas.

In a retrospective study, we investigated 56 consecutive patients who had undergone radical intestinal resection for colorectal adenocarcinoma and who had developed local or distant recurrences of the disease. We found that the presence of a predominant sialomucin pattern at the margins of resection of the surgical specimen was correlated with a high percentage of local, endoluminal recurrence in the anastomotic mucosa. In contrast, no correlation could be found when the recurrences occurred in the outer tissues around the anastomosis or at some distance from it.

Adenocarcinoma↗
PubMed1988

Uncoupling of Na+H+ from Cl-HCO3- exchange under some steady state conditions in rabbit gallbladder.

The transapical Cl- influx and transepithelial Na+ transport were measured in rabbit gallbladder. Only 11.7% of the transported Na+ was found to be accompanied by HCO3-. 10(-4) M SITS eliminated the HCO3- dependent fraction of Cl- influx (50%) but did not significantly alter intracellular Na+ activity and Na+ transport. Exposure to HCO3-free salines or to 10(-4) M acetazolamide about halved Cl- influx and Na+ transport. 25 mM SCN- reduced Cl- influx to zero, decreased intracellular Na+ activity, but only halved Na+ transport which under these conditions was abolished only in the absence of HCO3-. Exposure to a Cl- -free saline produced effects similar to those caused by SCN-. These results suggest that when Cl-/HCO3- exchange is inhibited at the apical membrane, Na+/H+ exchange and transepithelial Na+ transfer are unmodified if HCO3- is available for transport. The permanent uncoupling of the exchangers and the elevated transepithelial transport of Na+ are not due to an increased activity of the parallel Na+-Cl- cotransport but to a redirection of HCO3- flux toward the basolateral side.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1988

Remote effects of subcortical cerebrovascular lesions: a SPECT cerebral perfusion study.

The remote effects of small unilateral cerebrovascular lesions confined to subcortical structures were evaluated by single photon emission computerized tomography (SPECT) and a CBF tracer, I-123 HIPDM. A CBF study was performed in 34 patients presenting with subcortical stroke either in the acute or in the chronic stages. Twenty-one of the 34 patients showed areas of cortical hypoperfusion ipsilateral to the subcortical lesion. In 14 patients, asymmetry of perfusion was also observed at the cerebellar level, perfusion being significantly reduced in the cerebellar hemisphere contralateral to the lesion. There was no correlation between the degree and extension of these remote effects and the type of stroke (ischemic or hemorrhagic), the patency of cerebral arteries, or the size and site of the lesion by transmissive computerized tomography (TCT). Subcortical hematomas showed a correlation between occurrence of remote effects and time interval from the onset of stroke, occurring more frequently in the acute phase. A correlation was observed between cortical and cerebellar remote effects and the severity of clinical presentation. The causes of remote effects are still unclear and have been extensively debated. Our data indicate that there is a relationship of remote effect to the neurological status. It is possible to show, by noninvasive, low-cost methods, remote CBF effects after stroke that may contribute to the assessment of brain functional impairment.

Acute Disease↗
PubMed1987

Isolation of apical plasma membrane in rabbit gallbladder epithelium by Percoll density gradient centrifugation.

The apical membranes of rabbit gallbladder epithelial cells were isolated by treating the homogenate with Ca2+ or Mg2+ and centrifuging the suspension in Percoll gradient. In this way brush-border membranes were obtained with enrichment factors ranging between 10 and 20 and yields of 15-30%. A second method is described with which membranes were isolated, without any preliminary treatment, first by differential centrifugation, then with Percoll gradient; the final membrane enrichment was over 15, however the yield was very low (3%). Many possible enzymatic markers of the apical plasma membrane were investigated: L-gamma-glutamyltransferase, alkaline phosphatase, leucine aminopeptidase, sucrase. The first appears to be that of choice. Apical membrane fraction could be also evidenced by autofluorescence or by labeling with Lotus tetragonolobus lectin. Preliminary experiments showed that apical plasma membranes isolated in this way form vesicles.

Animals↗
PubMed1987

The nature of the neutral Na+-Cl(-)-coupled entry at the apical membrane of rabbit gallbladder epithelium: I. Na+/H+, Cl-/HCO3- double exchange and Na+-Cl- symport.

Cl- influx at the luminal border of the epithelium of rabbit gallbladder was measured by 45-sec exposures to 36Cl- and 3H-sucrose (as extracellular marker). Its paracellular component was evaluated by the use of 25 mM SCN- which immediately and completely inhibits Cl- entry into the cell. Cellular influx was equal to 16.7 mu eq cm-2 hr-1 and decreased to 8.5 mu eq cm-2 hr-1 upon removal of HCO3- from the bathing media and by bubbling 100% O2 for 45 min. When HCO3- was present, cellular influx was again about halved by the action of 10(-4) M acetazolamide, 10(-5) to 10(-4) M furosemide, 10(-5) to 10(-4) M 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonate (SITS), 10(-3) M amiloride. The effects of furosemide and SITS were tested at different concentrations of the inhibitor and with different exposure times: they were maximal at the concentrations reported above and nonadditive. In turn, the effects of amiloride and SITS were not additive. Acetazolamide reached its maximal action after an exposure of about 2 min. When exogenous HCO3- was absent, the residual cellular influx was insensitive to acetazolamide, furosemide and SITS. When exogenous HCO3- was present in the salines, Na+ removal from the mucosal side caused a slow decline of cellular Cl- influx; conversely, it immediately abolished cellular Cl- influx in the absence of HCO3-. In conclusion, about 50% of cellular influx is sensitive to HCO3-, inhibitable by SCN-, acetazolamide, furosemide, SITS and amiloride and furthermore slowly dependent on Na+. The residual cellular influx is insensitive to bicarbonate, inhibitable by SCN-, resistant to acetazolamide, furosemide, SITS and amiloride, and immediately dependent on Na+. Thus, about 50% of apical membrane NaCl influx appears to result from a Na+/H+ and Cl-/HCO3- exchange, whereas the residual influx seems to be due to Na+-Cl- cotransport on a single carrier. Whether both components are simultaneously present or the latter represents a cellular homeostatic counter-reaction to the inhibition of the former is not clear.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗