Simultaneous determination of bupivacaine, mepivacain, prilocaine and ropivacain in human serum by liquid chromatography–tandem mass spectrometry

A liquid chromatography-tandem mass spectrometric (LC-MS-MS) method with a rapid and simple sample preparation was developed and validated for the simultaneous determination of the local anesthetics bupivacaine, mepivacaine, prilocaine and ropivacaine in human serum. An external calibration was used. The mass spectrometer was operated in the multiple reaction monitoring mode. A good quadratic response over the range of 1.0-200.0 ng/ml was demonstrated. The accuracy for bupivacaine ranged from 93.2 to 105.7%, for mepivacaine from 96.2 to 104.3%, for prilocaine from 94.6 to 105.7% and for ropivacaine from 94.3 to 104.0%, respectively. The limit of quantification was 1.0 ng/ml for all substances. This method is suitable for pharmacokinetic studies.

The "bioeffect assessment index" (BAI). A concept for the quantification of effects of marine pollution by an integrated biomarker approach

The "bioeffect assessment index" (BAI) is based on the integration of several pathological endpoints measured in the liver of European flounder (Platichthys flesus (L.)) during a long term study of biological effects of pollution in the German Bight. The BAI represents a modification of the "health assessment index" since it includes solely validated biomarkers reflecting toxically induced alterations at different levels of biological organisation in order to quantify the effects of environmental pollution. The concept of the BAI is based on the observation of progressive deleterious effects from early responses to late effects. Specific "key events" were detected, representing progressive stages of functional deterioration. The biomarkers selected from a whole battery of cellular markers for the BAI calculation reflect deleterious effects of various classes of contaminants such as heavy metals, organochlorines, pesticides, PAHs, and therefore reflect general toxicity in an integrative manner. Selected biomarkers were: lysosomal perturbations (reduced membrane stability), storage disorders (lipid accumulation) as early markers for toxic effects of liver cells, and the size of macrophage aggregates and their acid phosphatase activity. The latter two markers are indicative for the modulation of non-specific immune response which represents longer time scale responses after chronic exposure.

The Elbe flood 2002--toxic effects of transported contaminants in flatfish and mussels of the Wadden Sea

Cellular changes in livers from flounder (Platichthys flesus L.) and digestive glands of blue mussels (Mytilus edulis) were studied to analyze whether the Elbe flood catastrophe in August 2002 had any deleterious effects on animal health. Flatfish and mussels were sampled at different locations in the Elbe estuary and the Wadden Sea after the flood wave had reached the German Bight. Internationally used core biomarkers (lysosomal membrane stability, biotransformation enzymes) were applied to assess the toxic effects of putatively increased pollution levels. In comparison to earlier data from long-term studies at the same stations, we found a significant impairment in the function of cell organelles (lysosomes) involved in the detoxification and elimination of pollutants in fish liver. Concentrations of relevant contaminants (organochlorines, polychlorinated biphenyls) were analyzed in parallel with cellular biomarkers, and conspicuously raised concentrations of insecticides metabolites were detected. Cell recovery and a clear reduction in contaminant concentrations were observed in fish livers five months after the flood at all sampling sites except the Helgolander Tiefe Rinne.

Second opinion pathology in liver biopsy interpretation

OBJECTIVE

Clinical management of liver diseases is often based on the interpretation of the pathologist examining liver biopsies. Many pathologists have little formal training and experience with these tissues. The magnitude of this problem is not determined yet. The goal of this study was to determine the diagnostic discrepancies that surfaced after a second opinion by experienced hepatopathologists interpreting liver biopsy tissues.

METHODS

All 178 consecutive liver biopsy tissue glass slides provided to hepatology consultants in 1996 and 1997 were selected for evaluation. Specimens with neoplasms, transplant-related indications, or those specifically referred by a community-based pathologist for consultation were excluded. Diagnosis and interpretations were compared with the reports from the original institutions. Discordant interpretations were grouped in major (description or diagnosis that would change management decisions) and minor (not likely to alter management) categories. Monetary cost of the pathology studies was analyzed.

RESULTS

A total of 125 specimens corresponding to 124 patients met inclusion criteria. Thirty-five (28%) and 47 (37.6%) biopsies had major and minor discrepancies, respectively. Full agreement was obtained in 43 (34.4%) cases. Fifteen (42.8%) of the major interpretation errors were on patients with chronic cholestatic disorders, nine (25.7%) with hepatocellular processes, and 11 (31.4%) were related to establishing the presence or absence of cirrhosis. Reviewing the 125 liver biopsies of this study by the consultants resulted in a 46% increase in monetary cost.

CONCLUSIONS

Practitioners making clinical decisions based on liver biopsy interpretation need to be aware that in a significant number of cases, pathologists are not able to arrive at a correct diagnosis, and thus seeking second opinions on the patients' behalf from experienced pathologists on liver diseases would be prudent. General pathologists should become more familiar with the abnormalities involving interlobular bile ducts and the diagnostic value of certain ancillary histological stains. Clinicians should provide pathologists with sufficient clinical information in terms of laboratory evaluations and clinical findings, so that accurate diagnosis might be facilitated.

Molecular cloning and characterization of endosialin, a C-type lectin-like cell surface receptor of tumor endothelium

Endosialin, the antigen identified with monoclonal antibody FB5, is a highly restricted 165-kDa cell surface glycoprotein expressed by tumor blood vessel endothelium in a broad range of human cancers but not detected in blood vessels or other cell types in many normal tissues. Functional analysis of endosialin has been hampered by a lack of information about its molecular structure. In this study, we describe the purification and partial amino acid sequencing of endosialin, leading to the cloning of a full-length cDNA with an open reading frame of 2274 base pairs. The endosialin cDNA encodes a type I membrane protein of 757 amino acids with a predicted molecular mass of 80.9 kDa. The sequence matches with an expressed sequence tag of unknown function in public data bases, named TEM1, which was independently linked to tumor endothelium by serial analysis of gene expression profiling. Bioinformatic evaluation classifies endosialin as a C-type lectin-like protein, composed of a signal leader peptide, five globular extracellular domains (including a C-type lectin domain, one domain with similarity to the Sushi/ccp/scr pattern, and three EGF repeats), followed by a mucin-like region, a transmembrane segment, and a short cytoplasmic tail. Carbohydrate analysis shows that the endosialin core protein carries abundantly sialylated, O-linked oligosaccharides and is sensitive to O-sialoglycoprotein endopeptidase, placing it in the group of sialomucin-like molecules. The N-terminal 360 amino acids of endosialin show homology to thrombomodulin, a receptor involved in regulating blood coagulation, and to complement receptor C1qRp. This structural kinship may indicate a function for endosialin as a tumor endothelial receptor for as yet unknown ligands, a notion now amenable to molecular investigation.

Is it safe to reuse disposable laparoscopic trocars? An in vitro testing

BACKGROUND

The reuse of disposable laparoscopic instruments carries a risk of transmitting infectious diseases such as hepatitis and HIV. We evaluated the safety of reusing disposable trocars by studying the chances of their harboring infectious viruses after resterilization in an in vitro setting.

METHODS

Disposable laparoscopic trocars were exposed to horse blood contaminated with high or low viral concentrations of herpes simplex virus type 1 (HSV1) and attenuated polio virus type 1 at room temperature for 2 h. HSV1 was chosen as the surrogate for lipid viruses that include hepatitis B and HIV virus; polio virus represented the nonlipid viruses that cause infections in immunocompromised patients and are more resistant to sterilization. The trocars were subsequently cleaned and resterilized by low-temperature steam and formaldehyde at 80 degrees C for 3 h. Viral cultures were then repeated after sterilization.

RESULTS

A cytopathic effect (CPE) was demonstrated at both concentrations for HSV1 in all trocars before but not after sterilization. For the polio virus, CPE was evident in 50% of the trocars (two of four) exposed to high viral concentration after sterilization.

CONCLUSION

Disposable trocars are difficult to resterilize and may harbor infectious viruses after their initial use. Therefore, the reuse of disposable trocars in laparoscopic surgery cannot be recommended.

Long-term results of surgical repair of bile duct injuries following laparoscopic cholecystectomy

BACKGROUND

Laparoscopic cholecystectomy (LC) is associated with an increased incidence of bile duct injuries when compared with the open surgical technique. Long-term results of repaired injuries and hepatic damage associated with chronic biliary obstruction are lacking.

METHODS

From Aug 1, 1991 until Dec 1, 1999, there were 27 patients referred for management of complex biliary injuries that occurred during LC. Patients underwent percutaneous transhepatic cholangiography and placement of transhepatic catheters with computed tomography-guided biloma drainage when indicated. On the basis of the cholangiography findings, patients underwent Roux-en-Y hepaticojejunostomy (HJ) and liver biopsy or were treated with nonsurgical interventions.

RESULTS

Twenty-one of 27 patients (77. 8%) underwent HJ, and 16 of these 21 patients (76.2%) also underwent hepatic biopsy. In 1 patient, a recurrent stricture developed at 20 months after the initial repair; and, in a second patient, an episode of cholangitis developed in the postoperative period with the transhepatic catheters in place. Five of 16 patients (31.2%) demonstrated marked hepatic fibrosis with 4 (25%) of these patients showing evidence of evolving cirrhosis at the time of HJ.

CONCLUSIONS

In this series with 55 months of follow-up, HJ repair of LC injuries was associated with an initial 95.2% success rate and an ultimate success rate of 100%. Despite this, delayed referral, averaging 12 months, was associated with significant hepatic injury in 5 of 16 (31.3%) patients who underwent biopsy.

In vivo inhibition of cysteine proteinases delays the onset of growth of human pancreatic cancer explants

An animal model was used to study the effects of oral treatment with a small molecular selective inhibitor of cysteine proteinases, Z-Phe-Arg-fluoromethylketone (Z-Phe-Arg-FMK) on primary tumour development. Poorly differentiated rapidly growing and moderately differentiated slowly growing human pancreatic tumours were implanted in the neck of nude mice that were orally treated or not with the inhibitor. Growth rates of the tumours were determined during 38 days after implantation. The poorly differentiated tumours were not affected by treatment with the inhibitor. Development of the moderately differentiated tumours was inhibited significantly by Z-Phe-Arg-FMK treatment. Moreover, the amount of stroma was increased and the volume of cancer cells was reduced in the moderately differentiated tumours that had grown in the treated animals. Reduction in size of the tumours was not achieved by reduction in growth rate but in a delay of the onset of growth. It is concluded that cysteine proteinases play a transient role at the start of tumour development only when cancer cells are surrounded by stroma as was the case in the moderately differentiated but not in the poorly differentiated pancreatic tumours. However, this role of cysteine proteinases can easily be taken over by other proteinases.

[Performance of different CT angiography imaging modalities in detecting renal artery stenoses]

PURPOSE

Purpose of the study was to compare the sensitivity and specificity of various display modalities in the detection of renal artery stenosis. In particular, the difference between hard-copy reading and interactive analysis at the workstation was assessed.

MATERIALS AND METHODS

Selected patients (n = 31) with expected suboptimal conditions for CT angiography due to long-standing hypertension and compromised renal function were included. Six radiologists evaluated independently a total of 77 renal arteries with 49 renal artery stenoses proven by angiography. Image analysis included: mode A: interactive display, analysis of multiplanar reformats and axial sections at the workstation, mode B: visualization of MIPs in the coronal and axial planes as hard copies only, mode C: visualization of MIPs and axial sections as hard copies only.

RESULTS

The following sensitivities and specificities were found for internal readers and (readers from outside institutions): mode A: 94.8%, 87.9%, mode B: 97.7% (95.1%), 80.3% (75.4%); mode C: 97.0% (95.3%), 78.8% (76.6%). The differences were statistically not significant (p > 0.05).

CONCLUSIONS

Standardized hard copies of MIPs plus axial CT provide sufficient accuracy to detect renal artery stenosis compared to interactive imaging even in this highly selected group of patients.

Nefazodone-induced liver failure: report of three cases

BACKGROUND

Liver failure is a rare but devastating result of drug toxicity.

OBJECTIVE

To describe three cases of subfulminant liver failure that were probably caused by nefazodone, a new antidepressant that is a synthetically derived phenylpiperazine.

DESIGN

Case series.

SETTING

Two university medical centers and a children's hospital.

PATIENTS

Three women 16 to 57 years of age.

INTERVENTION

Two patients underwent liver transplantation; the third was listed for transplantation but subsequently improved.

MEASUREMENT

Liver biopsy.

RESULTS

Nefazodone was administered for 14 to 28 weeks before the onset of symptoms. The duration of jaundice before onset of encephalopathy ranged from 4 to 6 weeks. All cases of liver failure had similar histologic appearance, with prominent necrosis in the centrolobular areas (zone 3). One patient had successful liver transplantation, one underwent transplantation but died, and one improved without transplantation. The temporal onset of disease after the start of nefazodone therapy suggested severe hepatocellular injury caused by the drug.

CONCLUSIONS

Because nefazodone seems to cause severe hepatocellular injury in an idiosyncratic manner, routine liver chemistries should be performed before starting nefazodone therapy and patients should be monitored regularly. Therapy should be discontinued if liver enzyme concentrations become abnormal.

Paecilomyces varioti peritonitis in patients on continuous ambulatory peritoneal dialysis

Paecilomyces varioti infection is a rare cause of peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD). We report two patients who developed P varioti peritonitis complicating CAPD. The clinical features and microbiological data of seven other previously reported cases are reviewed. Approximately half of the patients had received multiple antibiotics before the onset of the peritonitis because of either bacterial peritonitis or exit site infection. There was no particular pattern of peritoneal dialysate cell count, which was characteristic in this fungal peritonitis. Although all patients survived, morbidity was high. All patients required antifungal chemotherapy and removal of peritoneal catheter for eradication of the organism. Amphotericin B was effective in most cases. Patients of all previously reported cases did not go back to peritoneal dialysis after removal of peritoneal catheters. A combination of oral flucytosine and itraconazole was successful in treating our two patients. Although we managed to resume CAPD in our two patients with good functional outcome, abscesses and adhesions were major problems rendering most patients from other series failing to return to CAPD after recovery.

Multiple chromosomal aberrations and 11p allelotyping in lung cancer cell lines

Cytogenetic and molecular genetic studies have implicated many chromosomal aberrations in the pathogenesis of lung cancer. Deletions on 3p and 9p are presently the primary target for positional cloning of putative tumor suppressor genes. We have recently reported frequent loss of heterozygosity in three separate regions (HRAS, D11S12, D11S16) on 11p in freshly resected lung cancer specimens. Here we report cytogenetic and molecular genetic analyses of 26 permanently growing human lung cancer cell lines. Deletions indicating regions which may harbor potential tumor suppressor genes were found in 5/9 cell lines on 2p, 5/9 on 2q, 6/9 on 3p, 7/9 on 3q, 5/9 on 6q, 3/9 on 9p, 5/9 on 11p, and 6/9 on 13q. Reduction to hemizygosity or a statistically significant increase in the frequency of homozygosity on 11p was found for all markers investigated except for ST5 (D11S832E). Eight of twenty-six (31%) cell lines were hemizygous for D11S12 and 9/26 (35%) for D11S16. Seventeen of eighteen (94%) cell lines were homozygous for PTH (expected homozygosity, 53%), 15/15 (100%) for WT1 (expected homozygosity, 55%), and 16/18 (89%) for CAT (expected homozygosity, 50%). These results confirm the notion that 11p harbors several putative tumor suppressor genes which may become inactivated at different stages of tumor development and progression. They also provide a basis for selecting cell lines for genetic complementation specifically targeted at the regions described.

Cutaneous protothecosis: report of a case in Hong Kong

We report a patient who presented with recalcitrant ulcerated papules and plaques on both legs. Histopathology revealed protothecosis, and subsequent culture of the lesions grew Prototheca wickerhamii. Gradual resolution of the ulcers occurred on treatment with itraconazole.

[The possibilities of diagnosing the act of swallowing in contrast medium aspiration]

19 patients with contrast agent aspiration were examined prospectively utilizing a combined approach of an orally administered low-osmolal and non-ionic contrast agent and a digital X-ray system with a dynamic technique (8 images/s). This combined technique enabled a sufficient assessment of the aspiration mechanisms in all patients.

Increased efficacy of radiation therapy by use of proton beam

Proton beam treatment techniques provide a powerful approach to improving dose distribution (decrease treatment volume towards target volume) and hence increasing dose to target with resultant higher tumor control rates and lesser morbity. To achieve these dose distributions in patients requires use of modern imaging techniques, rigid immobilization systems, confirmation of target position vis a vis the proton beam at each treatment session, treatment planning which feature beam's eye view, displays of uncertainty, dose at each anatomic point, boli based on accurate assessment of density along each pixel, etc. Experience at MGH/MEEI/HCL has yielded a disease-free survival of 78% for patients with chordoma/chondrosarcoma of base of skull. Local control is achieved by 98% of patients treated for choroidal melanoma.

Considerations in fractionated proton radiation therapy: clinical potential and results

Protons have a finite range in tissue and can provide a better concentration of radiation dose in the tumor than conventional X-rays in certain situations. The development of optimized treatment plans for X-rays and protons followed by a comparative evaluation is one method of selecting tumor sites best suited for proton treatment. The preliminary results of comparative treatment planning for base of skull tumors and carcinoma of the prostate are discussed. These comparisons suggest a clinical gain for proton treatment of tumors in these locations. The clinical experience with fractionated proton treatment of several tumor sites is also discussed. The results of high dose proton treatment of chordomas and low grade chondrosarcomas of the base of skull is particularly promising: an actuarial 5-year local control of 78% has been obtained in 50 patients followed for a minimum of 22 months.

The risk of enucleation after proton beam irradiation of uveal melanoma

Enucleation after proton beam irradiation of uveal melanomas occurred in 64 (6.4%) of 994 eyes with a median follow-up time of 2.7 years. The median time between irradiation and enucleation in the 64 enucleated eyes was 13 months. The probability of retaining the eye was 95 and 90%, 2 and 5 years postirradiation, respectively. Three percent of eyes were enucleated during posttreatment year 1, and the yearly rate was 1% by the fourth year. No patient had enucleation later than 5 1/2 years posttreatment. The complication most likely to result in enucleation was neovascular glaucoma although this was frequently managed without enucleation. Other common reasons for enucleation were documented or suspected tumor growth and complete retinal detachment with associated loss of vision. The leading risk factors for enucleation were anterior tumor margin involving the ciliary body, tumor height greater than 8 mm, and proximity of the tumor to the fovea. Based on the presence or absence of these factors, 5-year eye retention rates were 99, 92, and 76% for low-, moderate-, and high-risk groups, respectively. Thus, the probability of eye retention after proton beam irradiation is high even among those at greatest risk of enucleation.

Metastasis from uveal melanoma after proton beam irradiation

The incidence of metastasis and prognostic factors for metastasis in 780 consecutive patients with uveal melanomas treated with proton beam irradiation were evaluated. Metastasis developed in 64 patients (8%). The median time from treatment to the diagnosis of metastasis was 2.1 years (range, 3 months to 7.3 years). The liver was primarily involved in 58 (90%) patients. The 5-year cumulative probability of metastasis developing was 20%. Prognostic factors for metastasis developing were quite comparable to those found for patients treated by enucleation and included largest tumor diameter, involvement of the ciliary body, older age, and extrascleral extension. Surgical localization, tumor height, and elevated liver enzymes before treatment were not important factors in the development of metastasis.

Characterization of the state of differentiation of six newly established human non-small-cell lung cancer cell lines

Six new non-small-cell lung cancer (NSCLC) cell lines were established directly from human tissue or indirectly via nude mouse xenografts in serum-supplemented media with success rates of 8% and 13%, respectively. They comprised one adenocarcinoma (ADLC-5M2), two squamous cell carcinomas (EPLC-32M1, EPLC-65H), two large cell carcinomas (LCLC-97TM1, LCLC-103H), and one malignant biphasic mesothelioma (MSTO-211H). All cell lines grew adherent to culture vessels with population doubling times (PDT) of 16-40 h, formed colonies in soft agarose with efficiencies of 0.1%-5.1%, and all grew in athymic nude mice. Xenograft histologies appeared as follows: (a) undifferentiated carcinomas with feeble resemblance to the original tumors in the case of adenocarcinomas and squamous cell carcinomas; (b) large cell carcinoma with high resemblance to the original tumor; (c) an undifferentiated tumor with predominance of large epithelial cells and few fibrous cells in the case of mesothelioma. Human chorionic gonadotropin (HCG) was found by radioimmunoassay and high-affinity binding sites for epidermal growth factor (EGF) by radio-receptor assay in 4/4 cell lines. A very low activity of L-DOPA decarboxylase (DDC) was detectable only in the adenocarcinoma cell line. All cell lines overexpressed the c-myc protooncogene, and no gene rearrangement or amplification was observed. Chromosome analysis revealed modal chromosome numbers of 70-73 in ADLC-5M2, EPLC-32M1, EPLC-65H, and MSTO-211H. Cell lines derived from large cell carcinoma had modal values of 65 and 170 and a wider chromosome distribution than all other cell lines. A NSCLC specific chromosomal aberration has been undetectable until now. These cell lines may aid in elucidating the biology of NSCLC and its interrelationship to other lung tumors.

Markers and characteristics of human SCLC cell lines. Neuroendocrine markers, classical tumor markers, and chromosomal characteristics of permanent human small cell lung cancer cell lines

Permanent human small cell lung cancer (SCLC) cell lines established in our laboratory were investigated for their expression of the enzymatic neuroendocrine markers L-DOPA decarboxylase (DDC), neuron-specific enolase (NSE), and creatine kinase (CK), including its BB isoenzyme (CK-BB), the classical tumor markers carcinoembryonic antigen (CEA), the alpha and beta subunits of human chorionic gonadotropin (alpha-HCG, beta-HCG), and alpha-fetoprotein (alpha-FP), and their chromosomal characteristics. DDC activities were detectable in 5/6 SCLC cell lines and absent in non-SCLC. NSE levels ranged from 160 to 1422 ng/mg soluble protein and were less than 290 ng/mg soluble protein in non-SCLC. Activities of CK and levels of CK-BB clearly distinguished SCLC from non-SCLC with CK activities greater than 1000 munits/mg soluble protein and CK-BB levels greater than 3000 ng/mg soluble protein in SCLC and less than 300 munits/mg soluble protein and less than 2000 ng/mg soluble protein in non-SCLC. CEA was detectable in 5/6 SCLC cell lines but absent in non-SCLC, and its level seemed to correlate with those of DDC, NSE, and CK. One cell line, SCLC-16H, lost some of its neuroendocrine properties and CEA after 1 year of in vitro cultivation. Generally, marker levels were low in fast growing cell lines and high in slow growing cell lines. HCG alpha and beta subunit and alpha-FP were not detectable in SCLC cell lines. All SCLC cell lines examined had near diploid DNA indices and modal chromosome numbers. Double minute chromosomes and homogeneously staining regions were found in 2/5 and 4/5 SCLC cell lines respectively. With respect to chromosomal aberrations, we found a deletion of the short arm of at least one chromosome 3 in all SCLC cell lines (5/5). These data show that SCLC expresses neuroendocrine markers and CEA; CK is the most sensitive marker, and DDC and CEA are the most specific markers for SCLC in vitro; individual marker levels correlate with each other and the in vitro malignancy of SCLC; and SCLC cell lines have relatively uniform chromosomal characteristics. Our results suggest that patients whose tumors have high levels of DDC, NSE, CK-BB, and CEA have a better prognosis than those with low marker levels. This hypothesis could be proved by comparing pairs of patients that are matched for all known prognostic parameters, in particular tumor spread, for their serum and tumor marker levels with respect to the patients' outcome and prognosis.

Characterization of two cell lines with distinct phenotypes established from a patient with small cell lung cancer

Two small cell lung cancer (SCLC) cell lines were established from pericardial and pleural effusions of a patient with histopathologically proven SCLC of the oat cell type. Chemotherapy was administered without response during the 148-day period prior to the establishment of the first cell line, SCLC-22H, and some of the same drugs were administered in the 15 days prior to the establishment of the second cell line, SCLC-21H. Both cell lines differed markedly in their biochemical, kinetic, and morphological properties. Although the biomarkers L-Dopa decarboxylase, bombesin, carcinoembryonic antigen, and neurotensin were detectable in SCLC-22H, they were undetectable or low in SCLC-21H. The population doubling time was twice as fast and the colony forming efficiency higher in SCLC-21H than in SCLC-22H. They both expressed high concentrations of the SCLC marker enzymes neuron-specific enolase and the creatine kinase isoenzyme BB and showed no significant differences in their chromosomal characteristics. c-myc was amplified and expressed in both cell lines, and SCLC-21H had an additional rearranged and amplified EcoRI c-myc fragment. Morphological differences were apparent in liquid culture, cytology, and xenograft histology; SCLC-21H grew much more loosely than SCLC-22H, and had more prominent nucleoli and more abundant cytoplasm. Ultrastructurally dense core granules were present in both cell lines. SCLC-21H thus expressed properties of the variant cell type of SCLC, whereas SCLC-22H had mixed classic/variant features. An in vivo progression of the patient's tumor from a pure small cell to a mixed small cell/large cell morphology could be demonstrated, which suggests that cell line SCLC-22H represents a cell type characteristic for the transitional phase of the tumor. The features of this cell line therefore define a new subclass of SCLC called transitional cell type. SCLC-22H may be of use to study the mechanisms involved in the classic to variant transition, which probably has a considerable impact on the prognosis and response to therapy.