Allograft tissue for use in valve replacement

Homograft or allograft tissue has been available for use as replacement for diseased valves or reconstruction of major vessels for decades. However, with respect to replacement of diseased valvular tissue the search for the ideal valve still continues. In this review we will discuss the clinical indications, surgical techniques, and outcome of aortic homografts.

Taurolidine improves survival by abrogating the accelerated development and proliferation of solid tumors and development of organ metastases from circulating tumor cells released following surgery

BACKGROUND

Surgical trauma is partly responsible for enhancing tumor growth through a variety of mechanisms that are still not fully elucidated. The use of perioperative immunostimulants may modulate these effects. This study examined the effect of administration of taurolidine after laparotomy or laparoscopy on the growth of solid tumor, the establishment of hepatic and lung metastases, and effects on natural killer (NK) and lymphokine-activated killer (LAK) cell function.

METHODS

B16 melanoma right flank tumors were established in mice (n = 180). These animals underwent anesthesia only (control) or laparotomy or laparoscopy (n = 60 per group) and were randomized to receive either saline or taurolidine (n = 30 per group) at specific time points. Survival was determined in each group, and in a further 90 mice tumor growth was followed over 10 days postoperatively. The experiment was repeated in 540 mice, which underwent one of the three procedures and were treated with either saline or taurolidine. NK and LAK cell cytotoxicity (NKCC, LAKCC) was determined at several time points postoperatively. In a further experiment, B16 melanoma tumor cells were delivered via tail vein injection (n = 180) and intrasplenic injection (n = 180). The effect of saline or taurolidine administration on survival after the establishment of metastases was determined, and again in a further 180 mice the establishment of metastatic deposits in the liver or lungs was determined after 8 days.

RESULTS

Survival appeared to be significantly decreased in both the solid-tumor model and the metastatic models undergoing laparotomy compared to laparoscopy and controls (P < 0.0001) and to a lesser extent in the laparoscopy group compared to controls (P < 0.001). Flank tumor growth and metastatic tumor formation were more significant in laparotomy groups compared to laparoscopy groups and controls, but also to a lesser extent in laparoscopy groups compared to controls (P </= 0.05). NKCC and LAKCC were significantly decreased in the same patterns (P < or = 0.03). However, treatment with taurolidine abolished these effects, restoring NKCC and LAKCC (P < or = 0.04) and laparoscopy groups (P < or = 0.001).

CONCLUSION

It appears that changes that occur after the trauma of laparotomy, and to a lesser extent, after laparoscopy, significantly enhance the growth of primary tumors as well as the development of metastases from circulating tumor cells and are associated with a suppression of host antitumor surveillance mechanisms. This not only affected tumor progression in the immediate postoperative period, but also ultimately affected survival. Taurolidine, a known immunostimulant, appears to abrogate the effects of surgical trauma on primary and metastatic tumor growth and also enhances survival. This may have significant value in the management of tumor-bearing patients undergoing resection.

Role of nitric oxide and protein kinase C in ACh-induced cardioprotection

We examined the roles of nitric oxide and protein kinase C (PKC) in ACh-produced protection of cultured cardiomyocytes during simulated ischemia and reoxygenation. Cell viability was quantified using propidium iodide in chick embryonic ventricular myocytes. O(2) radicals were quantified using 2',7'-dichlorofluorescin diacetate. After a 10-min infusion of ACh (0.5 or 1 mM) and a 10-min drug-free period, we simulated ischemia for 1 h and reoxygenation for 3 h. ACh reduced cardiocyte death [32 +/- 4%; n = 6 and 23 +/- 4%; n = 7 (P < 0.05)] and attenuated oxidant stress during ischemia and reoxygenation in a concentration-dependent manner compared with controls (47 +/- 4%; n = 8; P < 0.05). The increase in O(2) radicals before simulated ischemia [357 +/- 49; n = 4 and 528 +/- 52; n = 8 vs. 211 +/- 34; n = 8; P < 0.05 (arbitrary units)] was abolished by the specific nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) and was markedly attenuated by N(G)-monomethyl-L-arginine (L-NMMA). L-NAME or L-NMMA blocked the protective effects of ACh, which selectively increased PKC-epsilon isoform activity in the particulate fraction. The PKC inhibitor Gö-6976 had no effect on O(2) radical production before simulated ischemia but it abolished the protection; therefore nitric oxide is a large component of ACh-generated O(2) radicals. Nitric oxide and O(2) radicals activate the PKC-epsilon isoform by which ACh protects against injury.

Pharmacological evaluation of ricinine, a central nervous system stimulant isolated from Ricinus communis

The extract of the pericarp of castor bean (Ricinus communis) showed some typical central nervous system stimulant effects when administered to mice. The animals became exophthalmic, presented tremors and clonic seizures and died a few minutes after receiving larger doses of the extract. At lower doses the extract improved memory consolidation and showed some neuroleptic-like properties, such as a decrease in exploratory behavior and catalepsy. The memory-improving effect and the seizure-eliciting properties of the extract were also observed with the administration of ricinine, a neutral alkaloid isolated from the extract. However, the neuroleptic-like properties of the extract were not observed with ricinine. As the therapeutic index of ricinine is of the order of 200, the compound may be considered as a promising cognition-enhancing drug that may be used for the treatment of human amnesias.

The effect of laparotomy and laparoscopy on the establishment of spontaneous tumor metastases

BACKGROUND

Surgical extirpation of solid tumors may be entirely possible, and the consequence of surgical excision is invariably the release of tumor cells into the systemic circulation. The aim of this study was to determine whether laparotomy affects the establishment of spontaneous pulmonary metastases after excision of the primary tumor in a murine flank tumor model and to determine possible underlying immune abnormalities.

METHODS

An initial experiment was carried out to compare the development of gross spontaneous pulmonary metastases in the presence of a primary flank tumor and after excision of the tumor in C57/BL6 female mice. Another group of mice had flank tumors excised and were simultaneously randomized to undergo anesthetic only (control), laparoscopy, or laparotomy, after which the subsequent development of pulmonary metastases was determined. Finally, a third experiment entailed determination of natural killer cell (NK) cytotoxicity and the effect of splenic macrophages on NK cytotoxicity at days 1,7, and 14 after tumor excision.

RESULTS

Excision of the primary tumor resulted in a significant increase in the number of pulmonary metastases in mice compared with mice that did not have tumors excised (P = .01). Both laparotomy and laparoscopy significantly increased the number of spontaneous pulmonary metastases after tumor excision compared with controls (P < or = .01), and there was also a significant difference between laparotomy and laparoscopy groups (P = .00). NK cytotoxicity was significantly suppressed at all time points after operation in the laparotomy group compared with both the laparoscopy group and the controls (P < or = .01). Suppression occurred after laparoscopy at 24 hours after the procedure compared with controls (P = .00); by day 7 this difference was not significant, but as day 14 there was again a significant suppression (P < or = .03). Splenic macrophages appeared to be a suppressor to natural killer cell cytotoxicity (NKCC) in the corresponding groups and at the corresponding time points.

CONCLUSIONS

The differential establishment of spontaneous metastases after tumor excision and laparotomy and, to a lesser extent, laparoscopy results in lowered host antitumor surveillance and may be mediated at least in part by the generation of splenic suppressor cells in the early postoperative period, causing a more marked and prolonged effect after laparotomy than after laparoscopy.

Laparotomy and laparoscopy differentially accelerate experimental flank tumour growth

BACKGROUND

Surgery depresses host tumoricidal activity and may increase tumour growth. This study compared the effects of laparoscopy with laparotomy on extraperitoneal tumour growth and immune function in a murine model.

METHODS

C57BL/6 female mice aged 8-10 weeks had tumours induced in the right flank (n=45) and were randomized to undergo halothane anaesthesia only, laparoscopy or laparotomy. Flank tumour volume was assessed over 10 days. A second group of animals (n=540) were randomized to undergo the same procedures and killed at 24, 48 and 96 h. Splenocytes were harvested for natural killer (NK) cell and lymphokine activated killer (LAK) cell cytotoxicity studies.

RESULTS

There was a significant increase in flank tumour growth in the first 48 h after laparotomy and laparoscopy compared with controls (P < 0.01). By 96 h the difference was only significant in the laparotomy group (P< 0.01). Both NK and LAK cell cytotoxicities were suppressed significantly (P < or = 0.03) from 24 h up to 96 h following laparotomy compared with control and laparoscopy groups. There was also a significant suppression in the laparoscopy group compared with controls in the first 48 h after operation (P < or = 0.02).

CONCLUSION

Extraperitoneal tumour growth was significantly accelerated after laparotomy and correlated with significantly suppressed NK and LAK cytotoxicity for at least 4 days after operation. Laparoscopy had a shorter, less profound effect on tumour growth and immune function.

The effect of laparotomy and laparoscopy on the establishment of spontaneous tumor metastases

BACKGROUND

Surgical extirpation of solid tumors may be entirely possible, and the consequence of surgical excision is invariably the release of tumor cells into the systemic circulation. The aim of this study was to determine whether laparotomy affects the establishment of spontaneous pulmonary metastases after excision of the primary tumor in a murine flank tumor model and to determine possible underlying immune abnormalities.

METHODS

An initial experiment was carried out to compare the development of gross spontaneous pulmonary metastases in the presence of a primary flank tumor and after excision of the tumor in C57/BL6 female mice. Another group of mice had flank tumors excised and were simultaneously randomized to undergo anesthetic only (control), laparoscopy, or laparotomy, after which the subsequent development of pulmonary metastases was determined. Finally, a third experiment entailed determination of natural killer cell (NK) cytotoxicity and the effect of splenic macrophages on NK cytotoxicity at days 1,7, and 14 after tumor excision.

RESULTS

Excision of the primary tumor resulted in a significant increase in the number of pulmonary metastases in mice compared with mice that did not have tumors excised (P = .01). Both laparotomy and laparoscopy significantly increased the number of spontaneous pulmonary metastases after tumor excision compared with controls (P < or = .01), and there was also a significant difference between laparotomy and laparoscopy groups (P = .00). NK cytotoxicity was significantly suppressed at all time points after operation in the laparotomy group compared with both the laparoscopy group and the controls (P < or = .01). Suppression occurred after laparoscopy at 24 hours after the procedure compared with controls (P = .00); by day 7 this difference was not significant, but as day 14 there was again a significant suppression (P < or = .03). Splenic macrophages appeared to be a suppressor to natural killer cell cytotoxicity (NKCC) in the corresponding groups and at the corresponding time points.

CONCLUSIONS

The differential establishment of spontaneous metastases after tumor excision and laparotomy and, to a lesser extent, laparoscopy results in lowered host antitumor surveillance and may be mediated at least in part by the generation of splenic suppressor cells in the early postoperative period, causing a more marked and prolonged effect after laparotomy than after laparoscopy.

Normal inspiratory muscle strength is restored more rapidly after laparoscopic cholecystectomy

Respiratory complications after laparotomy cholecystectomy may result from generalised muscle weakness and fatigue, or from reduced respiratory muscle function secondary to an upper abdominal incision. In a prospective study we compared maximal inspiratory effort (Pimax/mmHg) and dominant hand grip strength (kPa) (expressed as a percentage of zero hour value) in patients undergoing open cholecystectomy (OC) (n = 12), laparoscopic cholecystectomy (LC) (n = 25) and a control group of patients undergoing lower limb surgery (n = 12). Of the 12 OC patients, three suffered respiratory complications: two had atelectasis and one a chest infection, compared with no such complications in the other two groups (P < 0.05). Pimax decreased postoperatively in all groups (P < 0.05) and had returned to normal by 48 h in the LC and control groups. In contrast, in the OC group Pimax fell from 112.5 +/- 17.8 mmHg to as low as 81.3 +/- 16.5 mmHg at 72 h and only returned to preoperative levels at 120 h. The hand grip strength fell significantly in all groups at 24 h (P < 0.05) but normal levels were achieved again by 48 h in all groups, and there was no significant difference in the hand grip strength between the groups over the 5 days. These results suggest that generalised muscle fatigue after surgery is similar after open and laparoscopic cholecystectomy. Open cholecystectomy does, however, cause a more prolonged reduction in respiratory muscle function and this is likely to contribute to the higher incidence of respiratory complications in this group of patients.

Physico-chemical surface characterization of hyaluronic acid derivatives as a new class of biomaterials

Three hyaluronic acid derivatives with different types and/or percentages of esterification, were analyzed by means of static contact angle measurements, SEM, ESCA, ATR/FT-IR, WAXS, DSC and TGA. The physico-chemical characterization of the three different samples, in both dry and wet state, was provided in terms of surface and bulk properties. ESCA and infrared analyses showed that the surface composition of all samples differs from that of the bulk. The hydrophilic-hydrophobic character of the samples changed according to the chemical composition as shown by ESCA and contact angle measurements. Both infrared and contact angle measurements reveal that surface restructuring occurred upon hydration for all the samples and the greater the hydrophilic character of the sample, the greater and faster the restructuring phenomenon. A clear picture of the different types of chemical groups has been established at different depth for the three materials.

[Influence of urban air pollution on DDT blood levels in children]

The blood levels of DDT in two groups of girls from two districts of São Paulo (Brasil) were the same. Both groups were equal in age and nutrition. The difference in air pollution showed no influence on the blood levels of DDT.