Clinicopathological analysis of local spread of carcinoma of the tongue

BACKGROUND

The aims of the study are three-dimensional analysis of mode and distance of local spread of oral tongue carcinoma.

METHODS

The glossectomy specimens were examined in the coronal plane in 3 mm thickness section.

RESULTS

There were 50 glossectomy specimens. The maximum spread was 1.8 cm. Ninety-six percent of specimens had local spread within 1.2 cm. The distance of spread was not correlated with tumor size, including the diameter, depth, and volume. The incidence of local recurrence was 27% with positive histological margin. Perineural infiltration was the most important prognostic factor for local recurrence and survival.

CONCLUSIONS

A minimum of 1.5-cm surgical resection margin is recommended. A smaller margin is not recommended as it has significant risk of local recurrence. A maximum of 2-cm surgical resection margin is recommended; larger margins will increase the surgical morbidity without a significant advantage of local control.

Helicobacter pylori and the null genotype of glutathione-S-transferase-mu in patients with gastric adenocarcinoma

BACKGROUND

Chronic Helicobacter pylori infection now is recognized as an important causative agent for gastric carcinoma. However, only a small minority of infected individuals develop the malignancy, even in areas with a high prevalence of gastric carcinoma. It has been postulated that the absence of glutathione-S-transferase-mu (GST-mu), which impairs detoxification of exogenous carcinogens, might predispose some infected individuals to the development of gastric carcinoma.

METHODS

Patients with histologically confirmed adenocarcinoma of the stomach were tested for H. pylori infection and the GST-mu genotype. Prevalence of GST-mu gene deletion was compared with the H. pylori status of the patients. A group of gender- and age-matched control subjects with known H. pylori-related nonulcer dyspepsia also were tested for the GST-mu genotype and compared with patients with H. pylori positive carcinoma.

RESULTS

Fifty-one patients with gastric adenocarcinoma were enrolled into the study. Thirty-five were found to have H. pylori in the resected specimens. The null genotype of GST-mu was significantly more common among those patients with H. pylori positive carcinoma compared with the H. pylori negative group (65.7% vs. 31.3%; P < 0.05). Homozygous deletion of GST-mu was significantly higher in the H. pylori positive carcinoma patients than in the H. pylori-infected, nonmalignant control group (65.7% vs. 37.1%; P < 0.05).

CONCLUSIONS

The null genotype for GST-mu is found more commonly in gastric carcinoma associated with H. pylori infection. The absence of the GST-mu enzyme may increase the risk of the development of gastric carcinoma in these patients.

Helicobacter pylori and the null genotype of glutathione-S-transferase-mu in patients with gastric adenocarcinoma

BACKGROUND

Chronic Helicobacter pylori infection now is recognized as an important causative agent for gastric carcinoma. However, only a small minority of infected individuals develop the malignancy, even in areas with a high prevalence of gastric carcinoma. It has been postulated that the absence of glutathione-S-transferase-mu (GST-mu), which impairs detoxification of exogenous carcinogens, might predispose some infected individuals to the development of gastric carcinoma.

METHODS

Patients with histologically confirmed adenocarcinoma of the stomach were tested for H. pylori infection and the GST-mu genotype. Prevalence of GST-mu gene deletion was compared with the H. pylori status of the patients. A group of gender- and age-matched control subjects with known H. pylori-related nonulcer dyspepsia also were tested for the GST-mu genotype and compared with patients with H. pylori positive carcinoma.

RESULTS

Fifty-one patients with gastric adenocarcinoma were enrolled into the study. Thirty-five were found to have H. pylori in the resected specimens. The null genotype of GST-mu was significantly more common among those patients with H. pylori positive carcinoma compared with the H. pylori negative group (65.7% vs. 31.3%; P < 0.05). Homozygous deletion of GST-mu was significantly higher in the H. pylori positive carcinoma patients than in the H. pylori-infected, nonmalignant control group (65.7% vs. 37.1%; P < 0.05).

CONCLUSIONS

The null genotype for GST-mu is found more commonly in gastric carcinoma associated with H. pylori infection. The absence of the GST-mu enzyme may increase the risk of the development of gastric carcinoma in these patients.

Clonality of lymphomas at multiple sites in SJL mice

SJL mice are an inbred strain of mice with a high incidence of spontaneous lymphomas of B-cell type often involving multiple abdominal organs, and are therefore a useful model for studying the clonal relationship among lymphomas at multiple sites. Thirteen SJL mice with well-developed tumors were killed at a median age of 56 weeks. Autopsy samples were taken from various enlarged lymphoid organs, and the histologic appearance of lymphomas was recorded. Using rearrangements of immunoglobulin genes (heavy and kappa-light chain genes) and integration patterns of murine leukemia virus as clonal markers, 7 of the 13 informative mice showed complete clonal identity among the different sites selected from each mouse; 5 of 13 mice demonstrated at least one shared clonal band with one or more markers being different among the different sites. The histologic appearance of the lymphomas from the various sites was found to be heterogeneous, even when there was clonal identity. These findings suggest that SJL lymphomas in multiple sites within one mouse are usually derived from a single clone but may show development of subclones within a major clonal population, thus supporting the notion that clonal evolution is a common event in the course of development of lymphoid neoplasia.

Helicobacter pylori and the null genotype of glutathione-S-transferase-mu in patients with gastric adenocarcinoma

BACKGROUND

Chronic Helicobacter pylori infection now is recognized as an important causative agent for gastric carcinoma. However, only a small minority of infected individuals develop the malignancy, even in areas with a high prevalence of gastric carcinoma. It has been postulated that the absence of glutathione-S-transferase-mu (GST-mu), which impairs detoxification of exogenous carcinogens, might predispose some infected individuals to the development of gastric carcinoma.

METHODS

Patients with histologically confirmed adenocarcinoma of the stomach were tested for H. pylori infection and the GST-mu genotype. Prevalence of GST-mu gene deletion was compared with the H. pylori status of the patients. A group of gender- and age-matched control subjects with known H. pylori-related nonulcer dyspepsia also were tested for the GST-mu genotype and compared with patients with H. pylori positive carcinoma.

RESULTS

Fifty-one patients with gastric adenocarcinoma were enrolled into the study. Thirty-five were found to have H. pylori in the resected specimens. The null genotype of GST-mu was significantly more common among those patients with H. pylori positive carcinoma compared with the H. pylori negative group (65.7% vs. 31.3%; P < 0.05). Homozygous deletion of GST-mu was significantly higher in the H. pylori positive carcinoma patients than in the H. pylori-infected, nonmalignant control group (65.7% vs. 37.1%; P < 0.05).

CONCLUSIONS

The null genotype for GST-mu is found more commonly in gastric carcinoma associated with H. pylori infection. The absence of the GST-mu enzyme may increase the risk of the development of gastric carcinoma in these patients.

Recurrent isolated extramedullary relapses as granulocytic sarcomas following allogeneic bone marrow transplantation for acute myeloid leukemia

Isolated extramedullary relapses as granulocytic sarcomas (GS) following allogeneic bone marrow transplantation (BMT) for acute myeloid leukemia (AML) are rare events. We describe three such patients who presented with a unique pattern of GS relapse post-BMT. The clinical features included repeated relapses in multiple sites, absence of marrow involvement, and prolonged survival. Fluorescence in situ hybridization (FISH) demonstrated persistence of donor hematopoiesis despite disseminated GS. The findings indicated that a graft-versus-leukemia (GVL) effect might operate more strongly in the marrow than in peripheral sites. Finally, our observations suggest that isolated GS relapses after BMT might be compatible with long survivals, and that in patients with marrow hematopoiesis of donor origin, augmentation of the GVL effect might be of use.

Post-transplantation lymphoproliferative disorder of donor origin in a sex-mismatched renal allograft as proven by chromosome in situ hybridization

We report a case of post-transplantation B-cell lymphoproliferative disorder (PTLPD) associated with Epstein-Barr virus (EBV) that developed in a renal allograft 5 months after transplantation. The lesion had a histologic appearance of diffuse large B-cell lymphoma with monoclonality demonstrated by in situ hybridization (ISH) for kappa and lambda mRNA. Both the male donor and the female recipient were EBV seropositive. The lymphoid cells in this lesion was proven to be of donor origin by ISH for the human Y chromosome on the paraffin-embedded sections of the allograft. The recipient of the other kidney from the same donor did not have evidence of lymphoma, and the patient was also free from disease 2 years after surgical removal of the lymphoma This case is an unusual PTLPD of donor origin; the majority of such lesions in solid organ transplantations are of recipient origin. Our findings demonstrate that the origin of PTLPD can be documented in selected cases using ISH with probes to the Y chromosome.

Bcl-6 gene hypermutations in diffuse large B-cell lymphoma of primary gastric origin

The presence of the bcl-6 gene hypermutation was studied in 40 Hong Kong Chinese patients with diffuse large B-cell lymphoma. The primary sites of involvement were nodal in 18 cases and gastric in 22. Hypermutations at the E1.11 segment of bcl-6 gene were detectable in 16/22 (73%) primary gastric and 4/18 (22%) primary nodal lymphoma (P<0.01). Three of the 22 cases of primary gastric but none of the nodal lymphoma had mutations at E1.12. The proportion of hypermutated cases in the group with bcl-6 gene rearrangement was similar to that of the germ-line group (70% v 75%). High frequency of bcl-6 gene hypermutations was found in diffuse large B-cell lymphoma of the stomach and they were independent of rearrangement of the gene as detected by Southern analysis. Unlike gene rearrangement, hypermutations of the bcl-6 gene did not appear to carry any prognostic significance clinically.

Nasal T/natural killer (NK)-cell lymphomas are derived from Epstein-Barr virus-infected cytotoxic lymphocytes of both NK- and T-cell lineage

The cellular nature of nasal T/natural killer (NK)-cell lymphomas (NLs) remains controversial. It is still debatable whether these represent T-cell lymphomas with extensive loss of surface antigens or are, in fact, true NK-cell lymphomas. They are associated closely with Epstein-Barr virus (EBV), to the extent that EBV-encoded small non-polyadenylated RNAs (EBER) expression can be used as a marker for the neoplastic cells. The cell lineage of this group of lymphomas was examined further by correlating immunophenotype, genotype and EBV status with the expression of cytotoxic granule-associated proteins, perforin and T-cell intracellular antigen-1 (TIA-1) in 13 cases of NL. Combined immunophenotypic and gene rearrangement analyses demonstrated that NLs can be identified clearly as either NK-cell or T-cell tumours. Nasal NK-cell lymphomas lacked clonal rearrangement of both T-cell receptor (TCR) gamma and immunogloulin heavy chain (IgH) genes and were either CD3(Leu4)-CD56+ (8 cases) or CD3(Leu4)+CD56+ (2 cases), whereas nasal T-cell lymphomas had rearranged TCRgamma and germ-line IgH genes and were either CD3(Leu4)+CD56+ (2 cases) or CD3(Leu4)+CD56- (1 case). Immunohistochemical (IH) studies showed that both perforin and TIA-1 were expressed universally in NL, irrespective of NK- or T-cell lineage. Dual labelling of TIA-1 by IH and EBER by in situ hybridisation demonstrated that the granule proteins were expressed predominantly by the EBER+ tumour cells. Our results indicate that NLs are derived from EBV-infected cytotoxic lymphocytes of both NK- and T-cell lineage. We postulate that cytotoxic lymphocytes generated during the cellular immune response to EBV infection or re-activation at the nasal region themselves may become targets for EBV infection and subsequent transformation.

Identification of two tyrosine phosphoproteins, pp70 and pp68, which interact with phospholipase Cgamma, Grb2, and Vav after B cell antigen receptor activation

Tyrosine phosphorylation of cellular proteins mediates the assembly and localization of effector proteins through interactions facilitated by modular Src homology 2 (SH2) and phosphotyrosine binding domains. We describe here two tyrosine-phosphorylated proteins with Mr values of 70,000 and 68,000 that interact with Grb2, phospholipase C (PLCgamma1 and PLCgamma2), and Vav after B cell receptor cross-linking. The interaction of pp70 and pp68 with PLC and Vav is mediated by the carboxyl-terminal SH2 domain of PLC and the SH2 domain of Vav. In contrast, the interaction of pp70 and pp68 with Grb2 requires cooperative binding of the SH2 and SH3 domains of Grb2. Western blot analysis demonstrated that neither pp70 nor pp68 represented the recently described linker protein SLP-76, which binds Grb2, PLC, and Vav in T cells after T cell receptor activation. Moreover, SLP-76 protein was not detected in a number of B cell lines or in normal mouse B cells. Hence, we propose that pp70 and pp68 likely represent B cell homologs of SLP-76 which facilitate and coordinate B cell activation.

The Syk and ZAP-70 SH2-containing tyrosine kinases are implicated in pre-T cell receptor signaling

An early stage in thymocyte development, after rearrangement of the beta chain genes of the T cell receptor (TCR), involves expression of the pre-TCR complex and accompanying differentiation of CD4(-)CD8(-) double negative (DN) cells to CD4(+)CD8(+) double positive (DP) cells. The ZAP-70 and Syk tyrosine kinases each contain two N-terminal SH2 domains that bind phosphorylated motifs in antigen receptor subunits and are implicated in pre-T receptor signaling. However, mice deficient in either ZAP-70 or Syk have no defect in the formation of DP thymocytes. Here we show that, in mice lacking both Syk and ZAP-70, DN thymocytes undergo beta chain gene rearrangement but fail to initiate clonal expansion and are incapable of differentiating into DP cells after expression of the pre-TCR. These data suggest that the ZAP-70 and Syk tyrosine kinases have crucial but overlapping functions in signaling from the pre-TCR and hence in early thymocyte development.

Restoration of thymocyte development and function in zap-70-/- mice by the Syk protein tyrosine kinase

The Syk family of protein tyrosine kinases, consisting of ZAP-70 and Syk, associate with the pre- and alphabeta T cell antigen receptors (TCRs) and undergo tyrosine phosphorylation and activation following receptor engagement. Thymocyte development in zap-70-/- mice is blocked at the CD4+CD8+ TCR(lo) stage. The presence of Syk in the thymus has raised the possibility that Syk may be able to mediate TCR function. To determine if Syk can play a role in thymocyte development, we generated zap-70-/- mice expressing a human syk cDNA. Syk expression restored both thymocyte development and function. In addition, Syk function required the CD45 transmembrane protein tyrosine phosphatase. Hence, ZAP-70 and Syk can play overlapping functions and exhibit similar regulatory mechanisms in mediating alphabeta T cell development.

Protein tyrosine kinases in thymocyte development

Much has been learned over the past few years about how protein tyrosine kinases mediate pre-TCR and mature alphabetaTCR function. The highlights include understanding the roles and the distinct effects of the Src and Syk families of protein tyrosine kinases in thymocyte development and function.

Two cases of fatal strongyloidiasis in Hong Kong

Two cases of fatal strongyloidiasis associated with diabetes mellitus and malnutrition are reported. The patients presented with repeated vomiting and upper gastrointestinal bleeding respectively. Unusual findings in these two patients included: unexplained peripheral leukocytosis, pulmonary infiltrates, gastric aspirate leukocytosis, progression of gastrointestinal symptoms and concurrent presence of adult worms, eggs, filariform and rhabditiform larvae of Strongyloides stercoralis in alimentary canal specimens. Both patients succumbed while receiving treatment with mebendazole. The present report illustrates that unexplained gastrointestinal symptoms with extensive scratch marks below the umbilicus can be important clues to early diagnosis of the disease. In addition, the various presentations of S. stercoralis infestation are discussed with reference to predisposing factors. Current trends in laboratory diagnosis and therapeutic considerations are also delineated.

Endoscopic surgery of the oesophagus

Conventional surgical access to the oesophagus often requires a thoracotomy. The application of techniques borrowed from laparoscopic surgery allows transthoracic dissection of oesophagus without thoracotomy. These techniques are useful in treatment of oesophageal leiomyomas, motility disorders and iatrogenic perforations. Oesophageal resection for cancer can be accomplished using minimal access, either thoracoscopically or with the aid of an operating mediastinoscope. Whether these techniques should replace transthoracic or transhiatal oesophagectomy for most patients with cancer remains to be seen.

Stigmata of hemorrhage in bleeding peptic ulcers: an interobserver agreement study among international experts

BACKGROUND

Stigmata of hemorrhage predict rebleeding and outcome of patients with bleeding peptic ulcers. There are variabilities in reported incidences of stigmata and their respective rebleeding risks. We sought to study the interobserver agreement among experts.

METHODS

Between June 1994 and July 1994, 100 consecutive patients with bleeding peptic ulcers underwent videoendoscopy within 24 hours of their admissions. An edited videotape of these ulcers was compiled and sent to an international panel of 14 experts. They independently rated these ulcers exclusively into one of the six categories: spurting, oozing, nonbleeding visible vessel, adherent clot, flat pigmented spot, or clean based. Agreement between any two experts was expressed by a kappa estimate (kappa). Agreements over individual stigmata and a composite kappa estimate (kappa(w)) signifying overall agreement were also computed.

RESULTS

Out of the possible 91 pairwise kappa estimates among 14 experts, 35 (38.5%) were less than or equal to 0.40, indicating poor agreement. None of the kappa estimates was greater than 0.75. Composite kappa estimates for individual stigmata were as follows: spurting kappa = 0.664, oozing kappa = 0.420, nonbleeding visible vessel kappa = 0.342, adherent clot kappa = 0.426, flat pigmented spot kappa = 0.393, and clean-based ulcer kappa = 0.371. The weighted kappa estimate was 0.426.

CONCLUSION

Agreement between experts was poor in more than a third of occasions. Although the overall interobserver agreement was fair (0.4 < kappa < 0.75), agreements for nonbleeding visible vessels, flat pigmented spots, and clean-based ulcers were poor.

CD56+ NK lymphomas: clinicopathological features and prognosis

The surface molecule CD56 marks a category of malignant lymphoma of putative natural killer (NK) cell origin. We conducted a retrospective analysis of 24 cases of CD56+ NK lymphoma/leukaemia to define the clinicopathologic and prognostic features of this specific group of lymphomas. 56 cases of nasal lymphomas and 204 cases with an initial diagnosis of peripheral T-cell lymphoma were retrospectively analysed. To specifically examine lymphomas of putative NK origin, only those that were negative for surface expression of CD3 but positive for CD56 were analysed. 24 cases were identified. The initial predominant sites of involvement were nasal (n = 18), palate (n = 1), nodal (n = 1) and multi-organ (n = 4). Clinically, in patients with disease localized to one anatomical site (n = 20), most had symptoms confined to the nose, with a high percentage in early stage (I: 91%; IV: 9%). The marrow was not involved in any of these cases. However, patients with multi-organ involvement at presentation (n = 4) behaved differently. All presented acutely with pancytopenia, hepatosplenomegaly, and marrow infiltration with haemophagocytosis. A leukaemic phase was observed in one case. Anthracycline containing combination chemotherapy resulted in complete remission in 75% of patients with localized disease, but only in 25% with multi-organ involvement. The median survival of patients with localized disease was 12 months, compared with 2 months in the multi-organ group (P = 0.06); the disease-free survival was significantly better in the former (P < 0.01). The overall median survival of all patients was still poor at 11 months. We conclude that CD56+ NK lymphomas could be divided into two main patterns of disease presentations: localized (predominantly nasal), and multi-organ involvement. Each has different clinicopathologic and prognostic features. Conventional chemotherapy appeared ineffective for the majority of patients, and innovative treatment modalities are needed to improve outcome.

Randomised comparison between adrenaline injection alone and adrenaline injection plus heat probe treatment for actively bleeding ulcers

OBJECTIVE

To compare endoscopic adrenaline injection alone and adrenaline injection plus heat probe for the treatment of actively bleeding peptic ulcers.

DESIGN

Randomised prospective study of patients admitted with actively bleeding peptic ulcers.

SETTING

One university hospital.

SUBJECTS

276 patients with actively bleeding ulcers detected by endoscopy within 24 hours of admission: 136 patients were randomised to endoscopic adrenaline injection alone and 140 to adrenaline injection plus heat probe treatment.

MAIN OUTCOME MEASURES

Initial endoscopic haemostasis; clinical rebleeding; requirement for operation; requirement for blood transfusion; hospital stay, ulcer healing at four weeks; and mortality in hospital.

RESULTS

Initial haemostasis was achieved in 131/134 patients (98%) who received adrenaline injection alone and 135/136 patients (99%) who received additional heat probe treatment (P = 0.33). Outcome as measured by clinical rebleeding (12 v 5), requirement for emergency operation (14 v 8), blood transfusion (2 v 3 units), hospital stay (4 v 4 days), ulcer healing at four weeks (79.1% v 74%), and in hospital mortality (7 v 8) were not significantly different in the two groups. In the subgroup of patients with spurting haemorrhage 8/27 (29.6%; 14.5% to 50.3%) patients from the adrenaline injection alone group and 2/31 (6.5%; 1.1% to 22.9%) patients from the dual treatment group required operative intervention. The relative risk of this was lower in the dual treatment group (0.17; 0.03 to 0.87). Hospital stay was significantly shorter in the dual treatment group than the adrenaline injection alone group (4 v 6 days, P = 0.01).

CONCLUSION

The addition of heat probe treatment after endoscopic adrenaline injection confers an advantage in ulcers with spurting haemorrhage.

Comparison of two-dimensional vs three-dimensional camera systems in laparoscopic surgery

BACKGROUND

The lack of depth perception and spatial orientation in video vision are the drawbacks of laparoscopic surgery. The advent of a three-dimensional camera system enables surgeons to regain binocular vision and may be advantageous in complex laparoscopic procedures.

METHODS

We prospectively studied two groups of surgeons (with and without experiences in laparoscopic surgery) who performed a designated standardized laparoscopic task using a two-dimensional camera system (Olympus OTV-S4) vs a three-dimensional camera system (Baxter-V. Mueller VS7700) and compared their time performances.

RESULTS

The results suggested that only experience in laparoscopic surgery had significant effect on individual's performance. We could not demonstrate any superiority of the 3D system over the 2D system. However, two-thirds of the surgeons commented that the depth perception did improve.

CONCLUSIONS

With further refinement of the technology, the 3D system may improve its potential in laparoscopic surgery.

Natural killer cell lymphoma/leukemia: pathology and treatment

Malignancies arising from cells of putative natural killer (NK) cell origin have increasingly been recognized as distinct clinicopathological entities. These malignancies are marked by tumour cells with NK cell characteristics, including the immunophenotype of CD2+, surface CD3-, cytoplasmic CD3 epsilon+, CD7 +/-, and CD56+, and the genotype of germline T cell receptor gene. A consistent association with monoclonal Epstein-Barr virus infection in the tumour cell has been observed. These tumours are now regarded as putative NK cell lymphoma/leukemia. Pathologically, tumour cells show variable cytological appearances, with frequent angiocentricity and angioinvasion, associated with zonal necrosis. Clinically, most cases occur in the nasal area and upper aerodigestive tract. However, occurrence in non-nasal sites such as the skin, gastrointestinal tract and testis is also observed. A particularly aggressive form of NK lymphoma/leukemia presents fulminantly as disseminated disease sometimes with a leukemic phase. All types of NK lymphoma/leukemia have an extremely poor prognosis with a median survival of less than a year. New modalities of treatment, including the use of high dose chemotherapy and stem cell rescue may be needed to improve treatment outcome.

Giant adrenal lipoma: a report of two cases and review of literature

Lipoma of the adrenal gland is extremely rare. We report two cases of adrenal lipomas, one in a 64-year-old female and the other a 78-year-old male. The sizes of these tumours (4.5 cm and 8 cm) were larger than those reported in the literature. Both cases were found incidentally, one at autopsy and the other during ultrasonographic examination for unrelated condition. The histogenesis, clinicopathological features, differential diagnosis and management of these cases are discussed.

Lymphoma of the breast in Hong Kong Chinese

Fourteen cases of non-Hodgkin's lymphoma presenting as breast mass from 1974 to 1996 were reviewed. The median age of presentation was 51 years. Three patients had bilateral disease and five had disseminated disease. A predominance of B cell disease of diffuse large cell histology was noted. Painless lumps were the most common presenting features and most patients were treated with excisional biopsy followed by combination chemotherapy. Radiotherapy was added to local bulky disease. Six patients, however, underwent mastectomy. The overall CR rate was 74 per cent, lasting a median of 32 months. At a median follow-up of 60 months five patients were still alive, one with relapsed disease. Salvage treatments for relapsed patients were uniformly poor. Compared to reported western series, our patients had more high grade disease, more T cell disease and more CNS relapses. Improvements in treatment may involve the use of fine needle aspiration of breast lesion prior to surgery, primary CNS prophylaxis in high grade disseminated disease and high dose chemotherapy with marrow/stem cell rescue in relapsed cases.

Recognition of unique carboxyl-terminal motifs by distinct PDZ domains

The oriented peptide library technique was used to investigate the peptide-binding specificities of nine PDZ domains. Each PDZ domain selected peptides with hydrophobic residues at the carboxyl terminus. Individual PDZ domains selected unique optimal motifs defined primarily by the carboxyl terminal three to seven residues of the peptides. One family of PDZ domains, including those of the Discs Large protein, selected peptides with the consensus motif Glu-(Ser/Thr)-Xxx-(Val/Ile) (where Xxx represents any amino acid) at the carboxyl terminus. In contrast, another family of PDZ domains, including those of LIN-2, p55, and Tiam-1, selected peptides with hydrophobic or aromatic side chains at the carboxyl terminal three residues. On the basis of crystal structures of the PSD-95-3 PDZ domain, the specificities observed with the peptide library can be rationalized.

Primary cardiac lymphoma

Primary cardiac lymphoma is a rare entity. We report on the clinicopathological features of 2 patients with primary cardiac lymphomas: one involving the right atrium resulting in intractable right heart failure, and the other involving the pericardium with massive pericardial effusion. In the first patient, sternotomy and surgical biopsy of the tumor were performed to arrive at the diagnosis. In the second patient, CT thorax and transesophageal echocardiography helped to diagnose the pericardial tumor, and cytological examination of the pericardial fluid established the pathological diagnosis of lymphoma. Combination chemotherapy (COPP) was started in both patients. The first patient died on the first day of chemotherapy due to intractable heart failure, while the second attained a partial response to chemotherapy but died of progressive disease 8 weeks later. This is followed by a literature review of 21 patients with primary cardiac lymphoma. In conclusion, the prognosis of primary cardiac tumor remains poor.

Pathogenesis of gastric lymphoma: the enigma in Hong Kong

BACKGROUND

Helicobacter pylori (H. pylori) infection has been postulated to be a pathogenetic factor in gastric lymphoma. However, the etiological factors for gastric lymphoma could vary in different populations.

MATERIALS AND METHODS

We looked for histological evidence of H. pylori infection in 53 gastrectomy specimens from Hong Kong Chinese patients with primary gastric B-lymphoma. We also screened for Epstein-Barr virus (EBV) in these cases using in situ hybridization with oligonucleotide probes for EBV-encoded small RNA1 and 2.

RESULTS

H. pylori was found in 29 of 53 (55%), including 8 of 13 (62%) cases of low-grade lymphoma of mucosa-associated lymphoid tissue (MALT) type. These infection rates in gastric lymphoma are lower than those reported in Western populations (80%-100%) and comparable to that found in healthy Chinese blood donors (55%) or in non-ulcer dyspeptic patients (52%-57%). EBV was found in tumor cells only in one case of high-grade gastric lymphoma with low-grade MALT component which was H. pylori-negative, and in occasional nontumor-lymphoid cells in 7 other cases.

CONCLUSIONS

These results suggest that (1) the role of H. pylori in pathogenesis of gastric lymphoma may vary in different populations; (2) very few gastric lymphomas are associated with EBV; (3) not all low-grade gastric MALT lymphomas are H. pylori-dependent.

Lymphoepithelioma-like carcinoma of the skin

The histopathological findings of two cases of primary lymphoepithelioma-like carcinoma (LELC) of the skin occurring in two elderly Chinese individuals are presented. Microscopically, they were well circumscribed and were composed of irregular nests of malignant epithelial cells in a background of reactive lymphoid cells including mature plasma cells. A focus of epithelial dysplasia was noted in the adjacent epidermis in one case, suggesting that the LELC might have originated from the overlying epidermis. The epithelial nature of the tumors was confirmed by cytokeratin staining. In situ hybridization for Epstein-Barr virus-encoded RNA (EBER) showed that the tumor cells were uniformly negative, although positive signals were detected in scattered background lymphocytes in case 1. Our results confirm the previous observation that LELC of skin is not related to Epstein-Barr virus, even in Chinese subjects. Nevertheless, such negative findings may prove to be of diagnostic value in excluding the alternative more common diagnosis of metastatic nasopharyngeal carcinoma, which is uniformly positive for EBER.

Primary B cell lymphoma of the mediastinum

Primary B cell mediastinal lymphoma has been recognized as a distinct entity recently. This is a retrospective study to define the clinical features and treatment outcome over a 10-year period. Twenty-four consecutive patients (male/female: 11/13) with B cell lymphoma primarily involving the mediastinum were studied. The median age was 34 years. Symptoms were mainly referrable to the chest, with superior vena cava syndrome (SVCO) present in one-third of the patients. Bulky disease was present in over half (58 per cent) and B symptoms were present in 38 per cent of patients. The overall CR rate was 70 per cent and the 5-year OS rates were 56 per cent and 72 per cent for all and CR patients respectively. Five (71 per cent) primary refractory patients and four (66 per cent) relapsed patients died despite salvage therapy. Six relapses occurred at a median of 6 months from treatment. This study showed that primary large B cell lymphoma of the mediastinum is a clinically distinct entity affecting young patients. A significant proportion attained CR and overall, more than half achieved prolonged remission, and most of the relapses occurred early. However, those who failed to attain CR or relapsed still had a poor outcome. An intensive therapy such as autologous bone marrow transplant has to be considered in this subgroup of patients.

Mesh hernioplasty using a stapler

BACKGROUND

The recent development of laparoscopic hernioplasty has evoked extensive re-examination of the safety and effectiveness of using synthetic mesh materials in hernia surgery. We have investigated the efficacy of anterior stapling mesh repair in the treatment of inguinal hernia.

METHODS

From July 1993 to June 1994, a modified open mesh hernioplasty using staples for anchorage has been performed in 127 patients.

RESULTS

The mean age of patients was 61.4 +/- 13.0 years. Over 90% of them were operated on under local anaesthesia. The operation time ranged from 30 to 95 min with a median of 39 min. Only sixteen patients (12.6%) required postoperative parenteral analgesics and the median time for resuming daily activities was 7 days. Apart from two patients with reactionary haemorrhage, there was no other significant complication observed. Only one recurrence was encountered over the 26-month median follow-up period.

CONCLUSIONS

We conclude that the modified mesh hernia repair with a stapling device is a feasible, inexpensive and safe procedure that is well tolerated under local anaesthesia by most patients.

Vitamin E potentiates arachidonate release and phospholipase A2 activity in rat heart myoblastic cells

Cytosolic phospholipase A2 (cPLA2) selectively catalyses the release of arachidonic acid from the sn-2 position of glycero-phospholipids to produce prostaglandins and leukotrienes. In this study, vitamin E enrichment of rat heart myoblastic H9c2 cells caused an increase in the release of arachidonate during ionophore (A23187) stimulation. PLA2 activity in the cytosolic fraction was also enhanced but enzyme activity in the particulate fraction was not affected by this treatment. Immunoblotting analysis with a polyclonal anti-cPLA2 antibody showed an increased level of the enzyme in vitamin E-treated cells. Direct incorporation of vitamin E into lipid vesicles in the assay mixture resulted in modulation of enzyme activity in a biphasic manner. Pretreatment of cells with phorbol 12-myristate 13-acetate, a known activator of protein kinase C, synergistically potentiated the ionophore-induced arachidonate release in both the control and vitamin E-treated cells. However, vitamin E treatment by itself did not affect the protein kinase C activity, indicating that the vitamin E-induced activation of cPLA2 was independent of the protein kinase C cascade. Collectively, these results suggest that vitamin E potentiates arachidonate release through the direct and/or indirect modulation of cPLA2 activity.

Distinct tyrosine phosphorylation sites in ZAP-70 mediate activation and negative regulation of antigen receptor function

Biochemical and genetic evidence has implicated two families of protein tyrosine kinases (PTKs), the Src- and Syk-PTKs, in T- and B-cell antigen receptor signaling. ZAP-70 is a member of the Syk-PTKs that associates with the T-cell antigen receptor and undergoes tyrosine phosphorylation following receptor activation. Three tyrosine residues, Tyr-292, -492, and -493, have been identified as sites of phosphorylation following T-cell antigen receptor engagement. Utilizing ZAP-70- and Syk-deficient lymphocytes (Syk-DT40 cells), we provide biochemical and functional evidence that heterologous trans-phosphorylation of Tyr-493 by a Src-PTK is required for antigen receptor-mediated activation of both the calcium and ras pathways. In contrast, cells expressing mutations at Tyr-292 or -492 demonstrate hyperactive T- and B-cell antigen receptor phenotypes. Thus, phosphorylation of ZAP-70 mediates both activation and inactivation of antigen receptor signaling.

Phosphorylation of SLP-76 by the ZAP-70 protein-tyrosine kinase is required for T-cell receptor function

Two families of tyrosine kinases, the Src and Syk families, are required for T-cell receptor activation. While the Src kinases are responsible for phosphorylation of receptor-encoded signaling motifs and for up-regulation of ZAP-70 activity, the downstream substrates of ZAP-70 are unknown. Evidence is presented herein that the Src homology 2 (SH2) domain-containing leukocyte protein of 76 kDa (SLP-76) is a substrate of ZAP-70. Phosphorylation of SLP-76 is diminished in T cells that express a catalytically inactive ZAP-70. Moreover, SLP-76 is preferentially phosphorylated by ZAP-70 in vitro and in heterologous cellular systems. In T cells, overexpression of wild-type SLP-76 results in a hyperactive receptor, while expression of a SLP-76 molecule that is unable to be tyrosine-phosphorylated attenuates receptor function. In addition, the SH2 domain of SLP-76 is required for T-cell receptor function, although its role is independent of the ability of SLP-76 to undergo tyrosine phosphorylation. As SLP-76 interacts with both Grb2 and phospholipase C-gamma1, these data indicate that phosphorylation of SLP-76 by ZAP-70 provides an important functional link between the T-cell receptor and activation of ras and calcium pathways.

Choledocholithiasis: comparison of MR cholangiography and endoscopic retrograde cholangiography

PURPOSE

To prospectively compare magnetic resonance (MR) cholangiography with endoscopic retrograde cholangiography (ERC) in the diagnosis of choledocholithiasis.

MATERIALS AND METHODS

Forty-seven patients with suspected choledocholithiasis underwent non-breath-hold, heavily T2-weighted, respiratory-triggered turbo spin-echo MR cholangiography. They then underwent ERC within 5 hours. The results of the two procedures were compared in 45 patients.

RESULTS

The absence of ductal dilatation was shown in 16 patients at MR cholangiography and at ERC. MR cholangiography showed common duct dilatation in 28 of the 29 patients with dilatation shown at ERC. MR cholangiography helped correctly identify 18 of the 19 patients with choledocholithiasis and 22 of the 26 patients without choledocholithiasis. Sensitivity with MR cholangiography was 95%, specificity was 85%, positive predictive value was 82%, and negative predictive value was 96%. Two of the false-positive findings were due to pneumobilia.

CONCLUSION

Non-breath-hold MR cholangiography is as accurate for the evaluation of choledocholithiasis as ERC.

Risk of further ulcer complications after an episode of peptic ulcer bleeding

To identify the risk factors for developing recurrent ulcer complications after recovery from an episode of peptic ulcer bleeding 611 patients admitted with peptic ulcer bleeding were studied. Some 557 (91 per cent) were discharged without operation. A total of 22 patients were lost to follow-up and five were excluded as maintenance H2 blockers were required. Of the remaining 530 patients at risk, 169 (32 per cent) developed another complication (166 bleeding, three perforations) over a median follow-up period of 36 months. Patients with duodenal ulcers at the time of bleeding, previous history of peptic ulcer, previous bleeding, history of dyspepsia longer than 3 months, and a short interval between previous ulcer complications and the index bleed were more likely to develop further complications. Sex, age, smoking, coexisting illness, non-steroidal anti-inflammatory drugs intake and time taken to achieve ulcer healing had no predictive value.

Epinephrine or epinephrine plus alcohol for injection of bleeding ulcers: a prospective randomized trial

BACKGROUND

Rebleeding following epinephrine injection of bleeding peptic ulcers occurs in 10% to 20% of all cases. The addition of a sclerosant has the theoretical advantage of inducing vessel thrombosis and permanent hemostasis.

METHODS

A prospective randomized controlled trial was conducted to compare injections with epinephrine alone or epinephrine plus absolute alcohol in patients with actively bleeding ulcers at endoscopy. Repeat endoscopy was performed 24 hours later; treatment was repeated in the presence of endoscopic signs of rebleeding. Surgery was performed when arterial bleeding could not be controlled endoscopically, clinical rebleeding with hematemesis or shock occurred, or the transfusion total exceeded 8 units.

RESULTS

One hundred sixty patients were enrolled (epinephrine alone, 81; epinephrine and absolute alcohol, 79). They were matched in age, sex, location of ulcers, hemoglobin on admission, shock, and severity of bleeding. Initial hemostasis was comparable: 79 of 81 with epinephrine alone (97.5%) versus 75 of 79 with epinephrine and absolute alcohol (94.9%). No difference was observed between the two with respect to either rebleeding (9 vs 6), need for emergency operation (12 vs 9), transfusion requirement (median, three units vs two units), hospital stay (median, 5 days vs 4 days), mortality (4 vs 7) and ulcer healing at 4 weeks (50 vs 46).

CONCLUSIONS

The additional injection of absolute alcohol after endoscopic epinephrine injection confers no advantage.

Collision tumour of the oesophagus: a challenge for histological diagnosis

An unusual case of mantle cell lymphoma metastasising to squamous cell carcinoma of the oesophagus, in a 62 year old Chinese man, is reported. A histological diagnosis based on examination of a small endoscopic biopsy specimen, in the absence of detailed clinical information, may be difficult, as the lymphoma component can be mistaken for reactive lymphoid infiltrate which is sometimes present adjacent to squamous cell carcinoma. Correlation with the clinical history, careful assessment of the subtle histological changes, and use of ancillary methods such as immunohistochemistry are most helpful in making the correct diagnosis. This case also illustrates further the possible occurrence of lymphomatous infiltrates surrounding other lesions in patients with a previous or concurrent history of lymphoma.

Regulation of antigen receptor signal transduction by protein tyrosine kinases

The past two years have seen further clarification of the early events occurring in antigen receptor signal transduction that are mediated by the immunoreceptor tyrosine-based activation motif (ITAM). The ITAM was shown to be a specific binding site for the ZAP-70/Syk protein tyrosine kinases and the structure of this complex was solved. In addition, possible mechanisms of activation and functions for these kinases were reported. Lastly, genetic studies established the critical importance of these kinases in antigen-receptor signaling and lymphocyte development.

Direct regulation of ZAP-70 by SHP-1 in T cell antigen receptor signaling

The threshold at which antigen triggers lymphocyte activation is set by the enzymes that regulate tyrosine phosphorylation. Upon T cell activation, the protein tyrosine phosphatase SHP-1 was found to bind to the protein tyrosine kinase ZAP-70. This interaction resulted in an increase in SHP-1 phosphatase activity and a decrease in ZAP-70 kinase activity. Expression of a dominant negative mutant of SHP-1 in T cells increased the sensitivity of the antigen receptor. Thus, SHP-1 functions as a negative regulator of the T cell antigen receptor and in setting the threshold of activation.

Clinical validation of the Geriatric Depression Scale (GDS): Chinese version

This study has attempted to validate the Geriatric Depression Scale translated version (Chinese) with a psychiatric outpatient sample (N = 461) of males and females aged 60 or above, from 10 government-maintained psychiatric outpatient clinics between January 1992 and February 1993. Reliabilities and validities were exceptional. Internal consistency reliability was .89 (alpha), and the test-retest reliability was .85 (alpha). Criterion-related (psychiatrist diagnosis) validity was good at .95, and concurrent validity (with CES-D) was .96. Item analysis also confirmed consistency--all 30 items were significantly correlated with the full GDS. However, its sensitivity (70.6%), specificity (70.1%), false negatives (29.4%), and false positives (29.9%), though acceptable, were not as impressive. The overall result has shown that the GDS is generally applicable to the Chinese elderly population and is good for measuring depressive symptoms. The scale can be easily applied in the community by health care professionals. However, further follow-up studies are recommended.

SH2 domain function is essential for the role of the Lck tyrosine kinase in T cell receptor signal transduction

Tyrosine kinase activity is required for signal transduction through the T cell antigen receptor (TCR). The Src family tyrosine kinase Lck appears to play a key role in the initiation of TCR signaling events. We have investigated the role of the phosphotyrosine-binding Src homology-2 (SH2), domain of Lck in TCR signaling. Lck containing a mutation in the phosphotyrosine binding pocket of the SH2 domain was expressed in an Lck-deficient cell line. We found that, in contrast to wild-type Lck, the SH2 domain mutant was unable to restore even the earliest TCR-mediated signaling events. To investigate the role of the Lck SH2 domain, we examined the association of tyrosine phosphoproteins with Lck. The predominant associated phosphoprotein was the ZAP-70 tyrosine kinase, which has also been implicated in the initiation of TCR signaling. In addition, the zeta subunit of the T cell receptor was found to weakly associate with Lck. Further analysis indicated that the SH2 domain of Lck can directly recognize both ZAP-70 and zeta in immunoprecipitates from TCR-stimulated cells. Our findings demonstrate that the SH2 domain of Lck is essential for the initiation of signaling events following TCR stimulation probably as a result of its ability to mediate an interaction between Lck and the ZAP-70 tyrosine kinase and/or the zeta subunit of the T cell receptor.

Granulocytic sarcoma of megakaryoblastic differentiation complicating chronic idiopathic myelofibrosis

We report the development of soft tissue granulocytic sarcoma with megakaryoblastic differentiation in a patient with chronic idiopathic myelofibrosis, which has hitherto been undescribed. Although an artifactual signet ring appearance of the blasts was found in the formalin-fixed tissue and caused diagnostic problems, the histological appearance on B-5 fixed material and immunophenotyping confirmed the diagnosis. Cytogenetic analysis showed 47,XY,+der(1)del(1)(?p13) at initial presentation and 47,XY,del(1)(?13),+der(1)del(1)(?p13) at the time of soft tissue blastic transformation, indicating that partial trisomy 1 might be of pathogenetic significance.

Follicular dendritic cell tumor of the liver. Evidence for an Epstein-Barr virus-related clonal proliferation of follicular dendritic cells

Tumors of the follicular dendritic cell are uncommon, and most occur as primary lymph node tumors. We report a case of primary follicular dendritic cell tumor of the liver that was initially reported as an inflammatory pseudotumor. The neoplasm recurred as two separate tumor masses 30 months after complete resection of the "hepatic inflammatory pseudotumor." It showed a wide spectrum of morphologic features ranging from areas with fascicles of very bland spindle cells amidst a background population of lymphocytes, reminiscent of inflammatory pseudotumor, to areas of dispersed sheets of highly pleomorphic tumor cells with a relative paucity of reactive inflammatory cells. The diagnosis was confirmed by positive immunohistochemical staining with CD21, CD35, R4/23, and Ki-M4 and by ultrastructural demonstration of convoluted interdigitating cell processes joined by desmosomes. The background lymphocytes were oligoclonal, CD8-positive T cells. In situ hybridization for Epstein-Barr virus (EBV)-encoded RNA was positive in the tumor cells in the original and recurrent tumors. More importantly, the cells showed identical episomal clonal EBV on Southern blot analysis, implying that the initial and recurrent tumors are due to clonal proliferation of EBV-positive neoplastic follicular dendritic cells. The tumor cells expressed latent membrane protein but not EBV-encoded nuclear antigen 2 (EBNA2) or ZEBRA. Such gene expression is very similar to that of Hodgkin's disease and nasopharyngeal carcinoma. The strong expression of latent membrane protein restricted to the tumor cells and the clonality of the EBV suggest that the virus may be involved in the pathogenesis of this tumor and not present merely as a "bystander."

Selective use of preoperative endoscopic retrograde cholangiopancreatography in laparoscopic cholecystectomy

BACKGROUND

The management of possible common bile duct (CBD) stones in patients scheduled for laparoscopic cholecystectomy remains controversial.

METHODS

Prospective evaluation of 609 patients who underwent laparoscopic cholecystectomy was carried out in relation to the use of selective preoperative ERCP for detection of common duct stones. Preoperative ERCP was performed if there is or has been (1) cholangitis, biliary pancreatitis, or jaundice; (2) abnormal serum liver tests or (3) ultrasonogram showing a dilated CBD or ductal stones.

RESULTS

A total of 139 patients underwent preoperative ERCP, and cannulation of CBD was successful in 133 patients (96%). CBD stones were found in 60 patients (45%) and extracted after sphincterotomy. High prevalence of CBD stones was noted in patients with acute cholangitis and CBD stones on ultrasonogram. There were six endoscopic sphincterotomy-related complications (complication rate, 4.5%): bleeding (2), pancreatitis (3), retroduodenal perforation (1). No patient required surgery as the result of a complication. The prediction of the occurrence of ductal stones was further analyzed using stepwise logistic regression. Acute cholangitis and CBD stones on ultrasonogram were shown to be independent significant risk factors with odds ratios of 8.9 and 13.5, respectively.

CONCLUSIONS

With selective preoperative ERCP, suspected CBD stones can be identified and removed prior to laparoscopic cholecystectomy.