Inhibition of cigarette smoke-related lipophilic DNA adducts in rat tissues by dietary oltipraz

The present study investigated the effects of dietary oltipraz on cigarette smoke-related lipophilic DNA adduct formation. Female Sprague- Dawley rats were exposed daily to sidestream cigarette smoke in a whole- body exposure chamber 6 h/day for 4 consecutive weeks. One group of rats was maintained on control diet while another group received the same diet supplemented with either a low (167 p.p.m.) or high (500 p.p.m.) dose of oltipraz, starting 1 week prior to initiation of smoke exposure until the end of the experiment. Analysis of lipophilic DNA adducts by the nuclease P1-mediated 32P-post-labeling showed up to five smoke-related adducts. Adduct no. 5 predominated in both the lung and the heart while adduct nos 3 and 2 predominated in the trachea and bladder, respectively. Quantitative analysis revealed that the total adduct level was the highest in lungs (270+/-68 adducts/10(10) nucleotides), followed by trachea (196+/-48 adducts/10(10) nucleotides), heart (141+/-22 adducts/10(10) nucleotides) and bladder (85+/-16 adducts/10(10) nucleotides). High dose oltipraz treatment reduced the adduct levels in lungs and bladder by >60%, while the reduction in lungs in the low-dose group was approximately 35%. In trachea, the effect of low and high dietary oltipraz on smoke DNA adduction was equivocal, while smoke-related DNA adducts in the heart were minimally inhibited by high-dose oltipraz. In a repeat experiment that employed a 3-fold lower dose of cigarette smoke, oltipraz (500 p.p.m.) was found to inhibit the formation of DNA adducts in rat lungs and trachea by 80 and 65%, respectively. These data clearly demonstrate a high efficacy of oltipraz in inhibiting the formation of cigarette smoke-induced DNA adducts in the target tissues.      

Increased susceptibility of peripheral mononuclear cells of leukemic patients to HTLV-I infection in vitro

Peripheral mononuclear cells (MNC) collected from 12 healthy donors and 44 leukemic patients at various stages of the disease were tested for natural killer (NK) activity and for their susceptibility to HTLV-I infection in vitro, measured in terms of percentage of p19 positive cells. MNC from leukemic donors at any stage of leukemia (ie, onset or relapse, ON/REL; complete remission or off-therapy, CR/OT donors) were highly susceptible to HTLV-I infection. This was true for acute leukemias of lymphoblastic (ALL) or nonlymphoblastic (ANLL) type. MNC of ON/REL patients were more susceptible to HTLV-I than those of CR/OT donors. In addition, leukemic blasts were more rapidly infected (ie, within five to seven days) than the HTLV-I-susceptible normal cord- blood lymphocytes. However, the presence of circulating blasts was not essential to virus susceptibility, since CR/OT MNC, presumably free of leukemic blasts, were still more susceptible to HTLV-I than normal cells. Basal NK function of MNC from leukemic patients was significantly lower than that detectable in healthy controls. However, no correlation was found between susceptibility to HTLV-I infection and NK activity.     

Suppression of apoptosis in hematopoietic factor-dependent progenitor cell lines by expression of the FAC gene

Fanconi anemia (FA) is a genetically heterogeneous, inherited blood disorder characterized by bone marrow failure, congenital malformations, and a predisposition to leukemias. Because FA cells are hypersensitive to DNA cross-linking agents and have chromosomal instability, FA has been viewed as a disorder of DNA repair. However, the exact cellular defect in FA cells has not been identified. Sequence analysis of the gene defective in group C patients (FAC) has shown no significant homologies to other known genes. The FAC protein has been localized to the cytoplasm, indicating that FAC may either play an indirect role in DNA repair or is involved in a different cellular pathway. Recent evidence has indicated that FA cells may be predisposed to apoptosis, especially after treatment with DNA cross-linking agents. The demonstration that genes can suppress apoptosis has been accomplished by overexpression of such genes in growth factor-dependent cell lines that die by apoptosis after factor withdrawal. Using retroviral-mediated gene transfer, we present evidence that expression of FAC in the hematopoietic factor-dependent progenitor cell lines 32D and MO7e can suppress apoptosis induced by growth factor withdrawal. Flow cytometry and morphologic analysis of propidium iodide stained cells showed significantly lower levels of apoptosis in FAC-retroviral transduced cells after growth factor deprivation. Expression of FAC in both cell lines promoted increased viability rather than proliferation, which is consistent with other apoptosis-inhibiting genes such as Bcl- 2. These findings imply that FAC may act as a mediator of an apoptotic pathway initiated by growth factor withdrawal. Furthermore, the congenital malformations and hematologic abnormalities characterizing FA may be related to an increased predisposition of FA progenitor cells to undergo apoptosis, particularly in the absence of extracellular signals.     

Factors that affect human hemopoiesis are produced by T-cell growth factor dependent and independent cultured T-cell leukemia-lymphoma cells

Some laboratory results and clinical situations suggest that human T cells may be important in the regulation of growth of hematopoietic cells. Since the discovery of T-cell growth factor (TCGF), systems are now available for the long-term specific in vitro propagation of mature normal or neoplastic human T cells, providing an opportunity to study the influence of T cells on hematopoiesis. Recently, 24 cell lines from patients with cutaneous T-cell lymphoma (CTCL) and T-cell acute lymphoblastic leukemia (T-ALL) were grown with TCGF and then assessed for release of humoral factors that affect hematopoiesis. Conditioned media (CM) from these cell lines were tested for erythroid burst- promoting activity (BPA) and granulocyte colony-stimulating activity (CSA). BPA was detected in CM from 3/6 cultures of T-ALL patients and 4/6 CTCL cultures. CSA was found in the CM from 6/8 cultures of T-ALL patients, 7/12 CTCL cultures, and 3/4 CTCL cell lines that become independent of exogenous TCGF for growth. The CSA from several of the neoplastic T-cell cultures stimulated high levels of eosinophil colonies, a possible source of the eosinophilia seen in these patients. The ability of continuously proliferating human T lymphocytes, which retain functional specificity and responsiveness to normal humoral regulation, to produce factors that directly or indirectly stimulate myeloid and erythroid colony formation lends further credence to the role of T lymphocytes in regulating hematopoiesis.     

Hemostatic plug formation in normal and von Willebrand pigs: the effect of the administration of cryoprecipitate and a monoclonal antibody to Willebrand factor

Hemostatic plug (HP) formation was investigated in the ear bleeding time incision in normal and von Willebrand pigs. HP volume was calculated by integrating the areas of serial sections. In normal pigs (n = 11), platelets immediately formed a layer on the surface of the cut channel. Platelet aggregates formed at the ends of transected vessels and gradually enlarged. Finally, all transected vessels were occluded by HP and bleeding stopped. In contrast, large HPs were formed in the incision in von Willebrand's disease (vWD) pigs (n = 4); these HPs did not cover the ends of the transected vessels, which continued to bleed, allowing the formation of large hemostatically ineffective platelet aggregates in the incision. Canals traversed these HPs, and bleeding from the open vessels may have continued through them. After infusion of cryoprecipitate into a vWD pig, the bleeding time shortened, and the morphological findings of the HPs were similar to those of normal pigs. In normal pigs (n = 3) infused with an anti- Willebrand factor monoclonal antibody, which prolonged the bleeding time, a large HP formed in the incision, similar to that observed in the vWD pig. The volume of the normal and vWD HPs increased with time. These in vivo findings suggest that Willebrand factor is involved in the localization of the HP to the damaged vessel and may also play a role in platelet-platelet interaction. A computerized morphometric technique was used for measuring the volume of the hemostatic plugs and the distance of sequential points on the perimeter of the HP from the center of selected bleeding vessels.     

A novel approach to improve undergraduate surgical teaching

Background:

Undergraduate surgery is at an important crossroads. Many departments report significant difficulties delivering effective teaching. Our student feedback indicated a dated surgical curriculum lacking structure, quality and uniformity. We report on a new ”blended” approach employing a combination of professional DVDs, case based discussions, online material and traditional bedside teaching designed to provide structure, standardization, and equality of learning .

Methods:

Year 4 students who had undertaken the new course and year 5 students who had participated in the traditional teaching programme were compared. Students completed a 20 item questionnaire about their experiences of the surgical teaching programme.

Results:

One hundred and seventy-one year 4 (70%) and148 year 5 students (66%) responded. Domains relating to “Overall Satisfaction with the course”, “Approval of innovative teaching methods and interactivity” and “Satisfaction with the clarity of course information” showed improvements when comparing the new and old programmes. However bedside teaching was not rated as highly in the new programme (p<0.05).

Conclusion:

This blended approach has resulted in improved student understanding and engagement. The apparent compromise of bedside teaching may be a reflection of higher expectations. We believe that a similar blended approach has the potential to re-invigorate surgical teaching elsewhere.     

Wound healing effect of methanolic leaf extract of Napoleona vogelii(Family:Lecythidaceae) in rats

Objective:To investigate the wound healing properly of Napoleona vogelii leaf extract in folkloric medicine.Methods:Roth sexes of adult albino rats(n=25) were used in this study and another group(n=30) were subjected to acute toxicity test(LD_(50)) of the plant extract.For the LD_(50),three randomized groups of 5 rats were first treated with 10,100,1 000 mg/kg body weight(bw),orally.This w as followed by a second treatment of 1500,3000,and 5 000 mg/kg bw of the leaf extract with continual monitoring of the animals for mortality or non-mortality.Incision wounds(1.3cm) were created on the skin of five groups of 5 rals using surgical blade under anesthesia.The first group was topically treated with petroleum jelly alone,group 2 was topically applied 400 mg/mL w/v of the reference drug,Neobaein,while group 3-5 were topically treated with 5-50 mg/mL w/v of the plant extract,respectively.Results:The percentage yield of the extract was 49.80%w/w dry matter.The phytochemical analysis revealed several bioactive constituents including glycosides,tannins,alkaloids,perpenoids.saponins,steroids,proteins,and carbohydrates.The LD_(50) was beyond our experimental limit and was not determined.Increased concentrations(5,20,and 50mg/mL w/v) of the extract had significant(ANOVA,P0.05) healing effect on the incision wounds giving rise to 125%-140% while treatmentawith Neobacin resulted in 150% healing effect on the third treatment regimen compared to the control(100%).Conclusions:These data indicate that Napoleona vogelii leaf extract contains potent bioactive compounds containing wound healing activity,substantiating its use as a wound healer in folkloric medicine.