The effect of a social support boosting intervention on stress, coping, and social support in caregivers of children with HIV/AIDS

BACKGROUND

Caring for the human immunodeficiency virus (HIV)-infected child is challenging and affects the entire family system. Studies have shown that social support can mitigate caregiver stress and enhance coping; however, social support may not always result in a positive outcome for the recipient.

OBJECTIVES

To measure caregiver stress, coping, and social support, and to test the effect of a social support boosting intervention on levels of stress, coping, and social support among caregivers of children with HIV/acquired immune deficiency syndrome (AIDS).

METHODS

An experimental design was used with monthly social support boosting interventions implemented. The stratified randomized sample included 70 primary caregivers of children with HIV/AIDS. The sample strata were seropositive caregivers (biological parents) and seronegative caregivers (foster parents and extended family members). Study measures included the Derogatis Stress Profile, Family Crisis Oriented Personal Evaluation Scale, and the Tilden Interpersonal Relationship Inventory. Data were analyzed using descriptive statistics and repeated measure MANOVA.

RESULTS

Statistically significant differences between the experimental and control groups were found on changes in the dependent variables over time when caregiver strata were included as a factor in the analysis; no statistically significant results were found when caregiver strata were combined. Univariate Ftests indicated that the level of social support for caregivers who were seronegative in the experimental group was significantly different from seronegative caregivers in the control group and seropositive caregivers in both groups. No significant treatment group differences were found for seropositive caregivers.

CONCLUSIONS

Seronegative caregivers derived substantial benefit from the social support boosting intervention. Seronegative caregivers who acquire a child with HIV/AIDS are confronted with a complex stressful situation; the critical need to enhance their social support is achievable through the intervention tested in this study.

The role of surgery in the treatment of clinically isolated adrenal metastasis

BACKGROUND

Clinically isolated adrenal metastasis is rare. The role of surgical resection is unknown. The aim of this study was to define clinical and pathologic parameters that might predict long term survival after resection of adrenal metastasis.

METHODS

The authors conducted a retrospective review of 37 patients who had undergone adrenalectomy for metastatic disease at the Memorial Sloan-Kettering Cancer Center (MSKCC) between July 1986 and October 1996. Patients who underwent resection of tumors that locally invaded the adrenal gland were excluded from the study, as were all patients with primary adrenal tumors.

RESULTS

There were 24 men and 13 women, with a median age of 58 years (range, 42-77 years). Lung carcinoma was the most common primary tumor (n = 17), followed by renal cell carcinoma (n = 9), and colorectal carcinoma (n = 5). The median length of stay at MSKCC was 8 days (range, 3-21 days). There was a 19% incidence of complications (12% major). There was one perioperative death. Five-year survival for the entire group was 24% (median, 21 months). Disease free interval (DFI) of > 6 months and complete resection were the only predictors of improved survival.

CONCLUSIONS

Adrenalectomy for clinically solitary, resectable lesions can be performed safely, and prolonged survival can be achieved in such selected patients. Adrenalectomy should be considered for patients with completely resectable disease and a DFI of > 6 months.

Laparoscopic resection of intra-abdominal testicular tumor

Intra-abdominal testicular neoplasms are difficult to diagnose, with open surgical exploration and excision the traditional mode of therapy. We report a patient with an intra-abdominal seminoma resected laparoscopically. In patients who present without evidence of retroperitoneal adenopathy, laparoscopy can be used for diagnosis, and with minimally invasive surgical techniques, to resect these tumors.

Wilms tumor and multicystic dysplastic kidney disease

PURPOSE

There is ongoing controversy concerning the management of multicystic dysplastic kidney disease, particularly with regard to the potential for malignant transformation. Our report fuels the debate by adding the 2 youngest patients in whom malignancy was present from birth or developed subsequently.

MATERIALS AND METHODS

Two well documented cases of malignancy associated with multicystic dysplastic kidney disease are presented in 2 female infants (5 and 3 months old). The 5-month-old female infant was followed for multicystic dysplastic kidney disease and had no evidence of tumor either antenatally or at birth. The 3-month-old presented with hypertension and interventricular septal defect. A renal tumor was present on initial ultrasound.

RESULTS

Even though malignant degeneration is rare in multicystic dysplastic kidney disease, 9 cases have been reported in the literature so far. Of these cases 3 were Wilms tumor, 5 were renal cell carcinomas and 1 mesothelioma.

CONCLUSIONS

Our 2 cases lend support to the surgical management of multicystic dysplastic kidney disease, particularly as nephrectomy can now be performed in a day surgery setting with minimal morbidity. Only the risks of coexisting malignancy and possible malignant degeneration transformation are specifically addressed in this article. Other complications of multicystic dysplastic kidney disease such as hypertension, infection, abdominal pain, hematuria and persistent dysplastic renal tissue despite ultrasonographic resolution of multicystic dysplastic kidney disease are additional risk factors to be considered. A recommendation for nephrectomy in all cases of multicystic dysplastic kidney disease cannot be based only on these 2 cases. Several other factors must be weighed before making that decision.

Magnetic resonance imaging compared with echocardiography in the evaluation of pulmonary artery abnormalities in children with tetralogy of Fallot following palliative and corrective surgery

BACKGROUND

Abnormalities of the pulmonary arteries following palliative or corrective surgery for tetralogy of Fallot (TOF) are common. Our purpose was to compare the usefulness of magnetic resonance imaging (MRI) and echocardiography in the post- operative evaluation of the pulmonary arteries in children with TOF.

OBJECTIVE

Our hypothesis was that MRI is more sensitive than echocardiography in the detection of branch pulmonary artery abnormalities in children with TOF.

MATERIALS AND METHODS

Pulmonary artery MRI and echocardiography were performed in 20 children following palliative and/or corrective surgery for TOF. MRI and echocardiography were compared in their ability to detect abnormalities of the pulmonary arteries. Angiographic or surgical correlation was available in 15 children. A perfusion scan for confirmation of pulmonary artery patency was available in one additional child.

RESULTS

Abnormalities of the branch pulmonary arteries identified by MRI included: absence or occlusion (2), focal stenosis (15), hypoplasia (2), aneurysm (1), and non-confluence (1). Echocardiography could not adequately visualize the right and left branch pulmonary arteries in eight and ten children, respectively. Echocardiography missed stenosis in 13 branch pulmonary arteries, patency of hypoplastic pulmonary arteries in two children, non-confluence of the pulmonary arteries in one child, and a left pulmonary artery aneurysm in one child. Abnormalities identified by MRI were confirmed in 16 children by angiography, surgery or perfusion scan.

CONCLUSION

MRI is more sensitive than echocardiography for the evaluation of branch pulmonary artery abnormalities in children following surgery for TOF.

Pancreatic injury in the hemolytic-uremic syndrome

In a retrospective review of 241 cases with hemolytic-uremic syndrome, there was evidence of pancreatic involvement in 2 patients, abnormal ultrasounds in 4 patients, and pancreatic injury in 3 of 8 patients undergoing autopsy. Pancreas ultrasound examination, available in 134 cases, was very valuable in identifying those with pancreatic injury.

Pathologic findings at the time of nephrectomy for renal mass

BACKGROUND

Ultrasound (US) and computed tomography (CT) have improved the diagnosis of solid renal masses. Nevertheless, some patients still undergo exploration for a presumptive diagnosis of renal cell carcinoma (RCC) and are found to have other pathology. We report a contemporary series of non-RCC renal masses (both incidental and symptomatic) among nephrectomies performed for suspected RCC.

MATERIALS AND METHODS

All nephrectomies performed by the Urology Service at the Memorial Sloan-Kettering Cancer Center from July of 1989 through July of 1996 for a parenchymal renal mass were reviewed, and patients without a final diagnosis of RCC were identified. Cases were excluded if RCC was not suspected preoperatively. Presentation, preoperative radiographic evaluation, type of operation, and pathologic features were assessed.

RESULTS

Of the 636 nephrectomies performed, 108 patients (16.9%) had a diagnosis other than RCC.

CONCLUSIONS

Of patients undergoing nephrectomy for renal masses, 16.9% have other pathologic diagnoses. Sixty-six percent of these non-RCC masses are discovered incidentally, and the majority are treated with radical nephrectomy. Preoperative radiographic evaluation reflects both clinical presentation, with IVP used to evaluate symptomatic tumors, and diagnostic uncertainty, with multiple modalities used to evaluate cystic lesions. This information has important implications for preoperative counseling and surgical planning.

Mutation frequencies at codon 248 of the p53 tumour suppressor gene are not increased in colon cancer cell lines with the RER+ phenotype

The replication-error positive (RER+) phenotype characterizes tumour cells with microsatellite instability. This 'mutator phenotype' is thought to induce spread mutations throughout the genome, thus increasing the risk of tumour development. Here we analyse spontaneously arising mutations at the tetranucleotide CCGG ( Msp I recognition site), at positions 14 067-14 070 of the p53 gene sequence, in three colon cancer cell lines, two with microsatellite instability and one without this characteristic. This restriction site covers hot-spot codon 248, which is often mutated in colon carcinomas. Using the Msp I RFLP-PCR assay we found that the mean mutation frequency at this site was not different among the cell lines considered. Taking the substitutions separately, none of the mutations involving codon 248 arose with significantly higher frequency in each of the RER+ cell lines (HCT116 and DLD1) compared with the RER-one (SW480). Only the CG transversion at nt 14 067 (codon 247) occurred with a slightly higher, but biologically insignificant, frequency in one of the RER+ cell lines (HCT116). Our in vitro data support the previously reported lack of correlation between microsatellite instability and p53 mutations in RER+ tumour specimens.

A fast and simple in situ PCR method to detect human papilloma virus infection in archival paraffin-embedded tissues

We describe a simple and fast method for the detection and localization of low copy numbers of HPV DNA in formalin-fixed and paraffin-embedded archival tissues. We have developed a protocol for direct bl situ-PCR in order to demonstrate its convenience in rapid and reproducible assessment of HPV infection in unknown biopsies. The morphological aspect of the tissues has been maintained, despite the multiple steps of fixation, permeabilization and thermal cycling, and positivity has been detected only in virus target cells.

Ureteral carcinoma in situ at radical cystectomy: does the margin matter?

PURPOSE

The clinical impact of ureteral carcinoma in situ identified at the time of radical cystectomy for bladder cancer has been poorly studied. We discuss our experience with this clinical problem in the context of published reports.

MATERIALS AND METHODS

A total of 31 patients with concomitant ureteral carcinoma in situ was retrospectively identified among 401 consecutive radical cystectomies. End points analyzed included positive urinary cytology, upper tract recurrence of carcinoma and cancer specific survival.

RESULTS

Ureteral margins were positive in 21 patients and negative in 10. Among 30 patients in whom it was performed frozen section failed to detect carcinoma in situ in 5 (16.6%) and sequential ureteral resection did not result in a negative margin in 15 (50%). In 3 patients upper tract carcinoma recurred at the anastomosis (1) and renal pelvis/ureter (2) at a median of 51 months (mean 49, range 36 to 59) following cystectomy. Positive cytology and upper tract carcinoma recurrence were not significantly associated with ureteral margin status, clinical or pathological bladder tumor stage or prior bacillus Calmette Guerin treatment. Median followup was 22.9 months (mean 31.8, range 2.0 to 74.2), during which 7 of the 31 patients died of metastatic bladder cancer.

CONCLUSIONS

Concomitant ureteral carcinoma in situ is uncommon, and is rarely associated with local morbidity. It appears to confer increased risk for upper tract carcinoma recurrence, irrespective of margin status. In our experience upper tract carcinoma recurrence is heralded by positive cytology and generally appears only with protracted followup. Prognosis appears to be determined by the bladder tumor. Given the lack of morbidity and mortality attributable to concomitant ureteral carcinoma in situ, and the limited ability of frozen section examination to assist in its extirpation, the value of intraoperative identification of concomitant ureteral carcinoma in situ is questionable and expectant management is advised.

Public health hazards from small ruminant meat products in Europe

Foodborne diseases, in particular those related to meat and meat products, have recently become a matter of great public concern. Sheep and goat meat can transmit infections and diseases either through handling during preparation procedures or as a result of ingestion by the consumer. The authors highlight the second route of contamination in relation to meat and meat products from small ruminants in European countries. Among the most important diseases transmitted by mutton and goat meat, toxoplasmosis remains the greatest threat, particularly in immuno-compromised people and in pregnant women. Other pathogens which may be associated with the consumption of meat from small ruminants include: Clostridium perfringens, Cryptosporidium parvum and Campylobacter jejuni. As with other ruminant species, Escherichia coli O157:H7 can be considered as an emerging pathogen, for which control efforts must be made. The classical zoonoses (brucellosis, Q fever, hydatidosis) are also presented here, although the major source of contamination for these diseases remains contact with infected animals or the handling of carcasses. The fact that the association of foodborne diseases with mutton and goat meat is less frequent than with the meat of other animal species should be noted, for the following reasons: a) lower levels of production; b) less intensive production, leading to a weaker microbial contamination; c) mutton and goat meat are subjected to processing less often than other meats; d) the usual boiling or cooking processes.

Renal oncocytoma: a clinicopathologic study of 70 cases

We reviewed 954 primary nonurothelial epithelial renal neoplasms with primary resection at Memorial Sloan-Kettering Cancer Center between the years 1980 and 1995 and classified 70 cases (7%) as renal oncocytomas. The study population was composed of 39 men and 31 women, and the mean age was 65 years (range 25 to 86 years). Fifty-six patients (80%) were asymptomatic at presentation, six (4%) had flank pain, six (4%) presented with a mass, and two (3%) had hematuria. Sixty-one were treated with total or radical nephrectomy, nine with partial nephrectomy. The right kidney was involved in 35 cases (50%), the left kidney in 32 (46%). Three cases (4%) were bilateral. Sixty-one cases (87%) were unifocal, nine (13%) multifocal. All the tumors were well circumscribed but unencapsulated. Forty-five (64%) were described as brown or red, whereas the remainder were variously described as tan to yellow. Central fibrosis or scar was described in 23 cases (33%), and gross areas of hemorrhage or cystic changes in 14 (20%). The mean size was 5.2 cm and median 5.0 cm (range 1.5 cm to 14 cm). Histologically, the tumors were characterized by a mixture of architectural patterns: compact cellular nests and acini embedded in a hyalinized, hypocellular stroma were present in 62 cases (89%), a solid nested architecture in 47 cases (67%), and a variable tubular component in 50 cases (71%). Small papillae, pseudopapillae, and intratubular epithelial tufts were seen in 19 cases (27%). Cytologically, the neoplasms also showed a mixture of cell types, the most common being the classic oncocyte, which consisted of round or polygonal cells with moderate to abundant granular, eosinophilic cytoplasm, and small round nuclei with evenly dispersed granular chromatin. Small basophilic nucleoli were visible in many of these cells in all cases. Thirty-one cases (44%) had a variable number of oncocytic cells with pyknotic nuclei and 20 (30%) contained clusters of small cells with a high nuclear/cytoplasmic ratio and dense hyperchromatic nuclei (so-called oncoblasts). Foci of tubules with clear cells embedded in a hyalinized stroma were present in six cases (9%). Cellular atypia was evident in 42 cases (60%) and was marked in 21 (30%). Eleven cases (16%) exhibited mitotic activity, albeit low. No case had atypical mitoses or necrosis. Twenty-two cases (31%) had areas of calcification within the hyalinized stroma, 12 (17%) had calcospherites, and three (4%) had osseous and myeloid metaplasia. Vascular invasion was present in three cases (4%), and invasion of perinephric fat in 14 (20%). One patient presented with liver metastasis. Fourteen cases (20%) were pT1, 42 (60%) pT2, and 14 (20%) pT3. After a mean follow-up of 58 months (range 1 to 181), 62 patients (89%) were alive with no evidence of tumor, six (9%) had died of other causes, one was alive with stable metastatic disease in the liver 58 months after diagnosis, and one died with metastatic disease to bone and liver. We conclude that renal oncocytomas have a varied morphologic appearance and their pathologic diagnosis should be based on a constellation of architectural and cytologic features. The overwhelming majority of cases behave in a benign fashion, although in rare instances they can metastasize. The presence of atypical morphologic features do not alter the excellent prognosis associated with oncocytomas and do not predict an aggressive clinical course.

Mechanism of resistance to cisplatin in a human ovarian-carcinoma cell line selected for resistance to doxorubicin: possible role of p53

A possible novel mechanism of cross-resistance to cisplatin (CDDP) in the doxorubicin-resistant ovarian-cancer cell line A2780-DX3, which displays atypical multidrug resistance, is presented. A2780-DX3 is found to be more resistant than the parental line A2780 in terms of CDDP-induced cytotoxicity and apoptosis. Resistance is not related to the amount of cross-links. Topoisomerase-II (topII) protein levels were similar in both cell lines, with lower cleavage activity in A2780-DX3 cells. The parental and the doxorubicin-resistant cells expressed the same level of c-erb2, which could be implicated in CDDP resistance. bcl2 was almost undetectable in both cell lines. At the same time, we found strong induction of p53, waf-1 and bax protein levels after CDDP treatment in the A2780, but not in the A2780-DX3, cell line. Treatment of both cell lines with mitomycin C (MMC), which acts with a mechanism different from CDDP, caused equal accumulation of p53 and induction of bax. We found that A2780-DX3 cells exhibit altered cellular localization of p53 protein in comparison with A2780. A significant proportion of p53 in A2780-DX3 cells was found in the cytoplasmic compartment, and CDDP treatment induced a functional p53 protein in the nucleus of A2780 much more strongly than in A2780-DX3, which coincides with an increase of transcriptional activity of p53 in treated A2780 cells. We propose that the cross-resistance to CDDP in the A2780-DX3 cell line may be due to inactivation of a CDDP-dependent p53-accumulation pathway.

Two cytodifferentiation agent-induced pathways, differentiation and apoptosis, are distinguished by the expression of human papillomavirus 16 E7 in human bladder carcinoma cells

Many transformed cells have been found to lose the capacity to proliferate and undergo differentiation following exposure to hybrid polar agents. This study investigates the mechanism by which hexamethylene bisacetamide (HMBA) suppresses the proliferation of the human bladder carcinoma line, T24. We found that following a 24-h exposure to HMBA, T24 proliferation was inhibited, and cells arrested in G1 phase and underwent morphological maturation. HMBA-induced cessation of proliferation was mediated, in part, by effects on cell cycle regulatory proteins. In T24 cells cultured without HMBA, E2F complexes predominantly with p107. In culture with inducer, p107 protein decreased, pRB and p130 were converted to underphosphorylated forms, and E2F was shifted into complexes with pRB and p130. To determine whether the formation of pRB:E2F and p130:E2F complexes was required for the HMBA-induced G1 arrest, the ability of the pocket proteins to bind E2F was blocked by enforced expression of human papillomavirus 16 E7. Following culture with HMBA, the T24 clones expressing E7 died, whereas vector-alone T24 clones arrested in G1 phase. T24/E7-1 cells did not form pRB:E2F or p130:E2F complexes upon culture with HMBA; rather, E2F was present in its free form. T24/E7-1 cells cultured with HMBA initially accumulate in G1. By day 2, they have entered into S phase, and by day 3, over 80% of the cells became apoptotic. Taken together, these studies enlarge the repertoire of demonstrated developmental pathways that may be triggered in transformed cells, depending upon their molecular status, and may provide potential therapeutic opportunities for cancer.

Nephrectomy during operative management of retroperitoneal sarcoma

BACKGROUND

Complete resection of a retroperitoneal sarcoma often requires removal of adjacent organs. In this study we evaluated the role of nephrectomy during operation for retroperitoneal sarcoma.

METHODS

Between July 1982 and July 1995, 75 of the 371 (20%) patients who underwent resection of retroperitoneal sarcoma at MSKCC underwent concommitant nephrectomy. Data concerning the reasons for nephrectomy, degree of sarcomatous renal involvement, and survival were retrospectively analyzed.

RESULTS

Fifty-four patients (72%) underwent nephrectomy during the initial resection, and 21 (28%) during a resection of a recurrent or persistent tumor. The most common reason for nephrectomy was total encasement by sarcoma (n = 40; 53%), followed by dense adherence of the tumor to the kidney (n = 21; 28%), and the direct invasion of the kidney by tumor (n = 2; 3%). Pathology demonstrated an absence of kidney invasion in the majority of cases (55 of 75; 73%). Renal capsular invasion was present in 11 of 75 (15%), renal parenchymal invasion in 7 of 75 (9%), and renal vein invasion in 2 of 75 (3%) of cases. There were no significant differences in survival based on degree of sarcoma involvement of the kidney, tumor grade, or whether the resection was for primary or recurrent disease. The 53 patients who underwent a complete gross resection of all tumor had a significantly improved long-term survival compared to the 20 patients who did not (50% versus 20% DFS at 5 years, respectively; p < 0.001).

CONCLUSIONS

Decisions for concomitant nephrectomy during resection of retroperitoneal sarcoma should be based on whether this maneuver will provide a complete resection of all gross tumor, in which case the long-term disease-free survival of 50% is comparable to the reported 5-year survival of all patients with retroperitoneal sarcoma who are completely resected.

MR imaging of carcinoma within urinary bladder diverticulum

Cystoendoscopic examination and standard radiological techniques occasionally fail to correctly establish that a pelvic mass is due to carcinoma arising within a urinary bladder diverticulum. MR imaging in oblique planes can facilitate the diagnosis in such cases by demonstrating the neck of the diverticulum. Also, T2-weighted images allow differentiation between tumor within a diverticulum and a necrotic extravesical mass.

Renal cell carcinoma

Renal cell carcinoma (RCC) is characterized by (a) lack of early warning signs, which results in a high proportion of patients with metastases at the time of diagnosis; (b) protean clinical manifestations; and (c) resistance to radiotherapy and chemotherapy. The estimates of new diagnoses and deaths from kidney cancer in the United States during 1996 are 30,600 and 12,000, respectively. RCC occurs nearly twice as often in men as in women. The age at diagnosis is generally older than 40 years; the median age is in the midsixties. The incidence of RCC has been rising steadily. Between 1974 and 1990, there was a 38% increase in the number of patients who had a diagnosis of RCC. This increase was accompanied by a significant improvement in 5-year survival. Both trends are likely the result of improved diagnostic capability. Newer radiographic techniques, including ultrasonography, computed tomography, and magnetic resonance imaging, are detecting kidney tumors more frequently and at a lower disease stage, when tumors can be resected for cure. Surgical treatment is the only curative therapy for localized RCC. Radical nephrectomy remains the mainstay of surgical management, but techniques are being modified. These modifications include partial nephrectomy and resection of vena caval thrombi. In highly selected cases, surgical resection of locally recurrent RCC or of disease at a solitary metastatic site is associated with long-term survival. Metastatic RCC is highly resistant to the many systemic therapies that have been extensively investigated. A minority of patients achieve complete or partial response to interferon, interleukin-2, or both. Response can be dramatic but is rarely durable. Because most patients do not achieve response, these agents are not considered effective treatments for RCC, but the response in some patients indicates the need for continued research on their use. Identification of new agents with better antitumor activity against metastases remains a high priority in clinical investigation of therapy for this refractory disease.

Toxicological effects of beryllium on platelets and vascular endothelium

Although ample research has described the toxic effects of the metal beryllium on the respiratory apparatus, less is known about its effects on the vascular apparatus, including pulmonary blood vessels. We investigated the in vitro effects of beryllium on endothelial vascular adenosine diphosphatase activity and prostacyclin production in bovine aortic endothelium, and on nitric oxide release in isolated rabbit arteries. Rabbit and human platelet responsiveness was also evaluated. Beryllium inhibited vascular endothelial adenosine diphosphatase activity, prostacyclin production, and nitric oxide release, thus inducing functional alterations in vascular endothelial cells. It also induced platelet hyperreactivity to arachidonic acid, as shown by a lowering of the threshold of aggregating concentration and by concurrently increasing thromboxane production. In contrast, beryllium left the response to aggregating and nonaggregating concentrations of ADP and collagen unchanged. These findings show that beryllium may impair some vascular endothelial functions and alter the interaction between platelet and endothelial mediators.

[Local administration of somatostatin in joint diseases in athletes]

Somatostatin is a hormone produced by the hypothalamus, and is widely diffused outside the CNS. It inhibits the secretion of many glands. Recently it has been shown that somatostatin has been proposed in the treatment of phlogistic diseases of the joints by intra-articular administration. The authors show the results of a study conducted in 16 patients (athletes) with arthrosynovitis or tendinitis of the knee or of the ankle, in which somatostatin was administered (250 mg/treatment, 1 treatment/week). Somatostatin significantly reduced pain, improved movement function and decreased the effects of pain on daily activities. The treatment was very well tolerated locally and generally. In conclusion, somatostatin may be considered useful in the treatment of articular and tendineous phlogistic diseases, almost in athletes.

Effects of Dex-Verapamil on Doxorubicin cytotoxicity in P388 murine leukemia cells

Resistance-modifying agents (RMAs) such as Verapamil have been proved to be effective in reversing multi-drug resistance (MDR) in many in vitro assays. In this study we have investigated the efficacy of Dex-Verapamil, the R-isomer of Verapamil, as a chemosensitizer in a murine leukemia cell line (P388) and in its resistant counterpart (P388/Dx) expressing a typical MDR phenotype. We have examined in vivo the effect of the co-administration of Dex-Verapamil and Doxorubicin in mice transplanted with P388 or P388/Dx cells. Mice treated with the combination of Doxorubicin plus RMA had a significant increase in survival rate as compared to controls; however, the effect was modest. On the contrary, in vitro Dex-Verapamil can enhance Doxorubicin cytotoxicity in P388/Dx cells with a much greater effect depending on the treatment scheme used, by increasing the intracellular content of drug. Taken together our data indicate that Dex-Verapamil can indeed increase the sensitivity to Doxorubicin in resistant cells, but the limited efficacy shown in vivo demonstrates that this phenomenon is strongly dependent on the treatment scheme used and on the maintenance of constantly elevated serum levels.