In vivo tumor targeting of a recombinant single-chain antigen-binding protein

We describe here the first in vivo targeting of tumors with a single-chain antigen-binding protein. The molecule, which was constructed and expressed in Escherichia coli, is a novel recombinant protein composed of a variable light-chain (VL), amino acid sequence of an immunoglobulin tethered to a variable heavy-chain (VH) sequence by a designed peptide. We show that this protein, derived from the DNA sequence of the variable regions of the antitumor monoclonal antibody B6.2, has the same in vitro antigen-binding properties as the B6.2 Fab' fragment. Comparative pharmacokinetic studies in athymic mice demonstrate much more rapid alpha and beta phases of plasma clearance for the single-chain antigen-binding protein than for the Fab' fragment, as well as an extremely rapid whole-body clearance. Half-life values for alpha and beta phases of single-chain antigen-binding protein clearance were 2.4 minutes and 2.8 hours, respectively, versus 14.8 minutes and 7.5 hours for Fab'. Furthermore, the single-chain antigen-binding protein molecule did not show accumulation in the kidney as did the Fab' molecule or, as previously shown, the F(ab')2 molecule. Despite its rapid clearance, the single-chain antigen-binding protein showed uptake in a human tumor xenograft comparable to that of the Fab' fragment, resulting in tumor to normal tissue ratios comparable to or greater than those obtained with the Fab' fragment. These studies thus demonstrate the in vivo stability of recombinant single-chain antigen-binding proteins and their potential in some diagnostic and therapeutic clinical applications in cancer and other diseases.

Meta-analysis examining the epidemiology of clozapine-associated neutropenia

BACKGROUND

Clozapine is associated with life-threatening neutropenia. There are no previous meta-analyses of the epidemiology of clozapine-associated neutropenia.

OBJECTIVES

To determine the cumulative incidence of mild, moderate and severe neutropenia, incidence of death related to severe neutropenia, case fatality rate of neutropenia and the longitudinal incidence of neutropenia following exposure to clozapine.

DATA SOURCES

A systematic search of Medline, EMBASE and PsycINFO using search terms [clozapine OR clopine OR zaponex OR clozaril] AND [neutropenia OR agranulocytosis].

METHODS

Random effects meta-analysis to determine event rates and longitudinal incidence of events per 100 person-years of exposure.

RESULTS

A total of 108 studies were included. The incidence of clozapine-associated neutropenia was 3.8% (95% CI: 2.7-5.2%) and severe neutropenia 0.9% (95% CI: 0.7-1.1%). The incidence of death related to neutropenia following prescription of clozapine was 0.013% (95% CI: 0.01-0.017%). The case fatality rate of severe neutropenia was 2.1% (95% CI: 1.6-2.8%). The peak incidence of severe neutropenia occurred at one month of exposure and declined to negligible levels after one year of treatment.

CONCLUSION

Severe neutropenia associated with clozapine is a rare event and occurs early with a substantial decline in risk after one year of exposure. Death from clozapine-associated neutropenia is extremely rare. Implications for haematological monitoring are discussed.

Angiotensin-converting enzyme and its clinical significance--a review

There have been considerable advances in understanding the metabolic role of the endothelial lining cells of the blood vessels. Angiotensin-converting enzyme activity is concentrated in these cells, especially those lining the pulmonary circulation. The enzyme exerts control over systemic vascular tone indirectly through the powerful pressor effect of angiotensin II. A number of therapeutic agents are now available which directly inhibit converting enzyme activity and thereby effect a reduction in blood pressure. Macrophages are the source of increased angiotensin-converting enzyme activity commonly found in association with active sarcoidosis. A better understanding of this phenomenon may give fresh insight into this puzzling condition. Pulmonary endothelial metabolism is affected by lung injury and it is likely that in this situation changing activities of serum angiotensin converting enzyme may indicate the extent of damage and the response to therapy. The full clinical significance of serum ACE measurements has yet to be established. However, raised activities have been reported in a number of other conditions and diabetes mellitus and hyperthyroidism are of particular current interest. The numerous methods and reference ranges described in the literature for the measurement of serum ACE activity require further assessment, and there is a clear need for an accepted reference method.

Serum angiotensin-converting enzyme (SACE) in sarcoidosis and other granulomatous disorders

Serum angiotensin-converting enzyme (SACE) activity was significantly higher in 90 patients with sarcoidosis (55 +/- [S.D.] 23 nmol min-1 ml-1) than in 80 healthy controls (34 +/- 9 nmol min-1 ml-1). Steroid therapy modified SACE activity; 60 sarcoidosis patients who were not being treated with steroids had significantly higher enzyme activities (58 +/- 24 nmol min-1 ml-1) than 30 steroid-treated sarcoidosis patients (40 +/- 19 nmol min-1 ml-1). In 50% of the non-steroid treated sarcoidosis patients SACE activity was more than 2 S.D. above the mean value for the controls. SACE activity was measured in 22 tuberculous patients (38 +/- 14 nmol min-1 ml-1), 20 leprosy patients (34 +/- 9 nmol min-1 ml-1), 31 with primary biliary cirrhosis (44 +/- 20 nmol min-1 ml-1), 26 with inflammatory bowel disease (31 +/- 9 nmol min-1 ml-1), 8 with hepatic granulomatous disease, 5 with Hodgkin's disease, and 2 with schistosomiasis. The combined false-positive rate for these non-sarcoidosis patients was 10%. Serial SACE assays provide useful information on the course of sarcoidosis and response to steroid treatment.

Stereotactic core-needle breast biopsy: a multi-institutional prospective trial

PURPOSE

To assess the accuracy of stereotactic core-needle biopsy (CNB) of nonpalpable breast lesions within the context of clinically important parameters of anticipated tissue-sampling error and concordance with mammographic findings.

MATERIALS AND METHODS

CNB was performed in 1,003 patients, with results validated at surgery or clinical and mammographic follow-up. Mammographic findings were scored according to the American College of Radiology Breast Imaging Reporting and Data System with a similar correlative scale for histopathologic samples obtained at either CNB or surgery. Agreement of CNB findings with surgical findings or evidence of no change during clinical and mammographic follow-up (median, 24 months) for benign lesions was used to determine results. Three forms of diagnostic discrimination measures (strict, working [strict conditioned by tissue sampling error], applied [working conditioned by concordance of imaging and CNB findings) were used to evaluate the correlation of CNB, surgical, and follow-up results.

RESULTS

Strict, working, and applied sensitivities were 91% +/- 1.9; 92% +/- 1.8, and 98% +/- 0.9, respectively; strict, working, and applied specificities were 100%, 98% +/- 0.8, and 73% +/- 0.9; strict, working, and applied accuracies were 97%, 96%, and 79%.

CONCLUSION

Percutaneous stereotactic CNB is an accurate method to establish a histopathologic diagnosis of nonpalpable breast lesions. Accuracy increases when additional surgery is performed for lesions with anticipated sampling error or when CNB findings are discordant with mammographic findings. An understanding of the interrelationship among these parameters is necessary to properly assess results.

Serum angiotensin converting enzyme in sarcoidosis--its value in present clinical practice

Angiotensin converting enzyme (ACE) has a central role in blood pressure homeostasis. It is present in low and fairly constant concentration in the serum and in high concentration in the pulmonary capillary bed. Unusually high serum angiotensin converting enzyme (SACE) activity is present in active sarcoidosis, an observation now confirmed by many investigators. In spite of its lack of specificity as a test for sarcoidosis, SACE provides a good monitor of disease activity which clinicians find useful in the management of patients with sarcoidosis. There continues to be considerable interest in SACE in sarcoidosis and with the recent development of simpler assays, more centres may be expected to offer SACE measurements as a service. In this paper we discuss the indications for estimating SACE in sarcoidosis and its relevance to current clinical practice.

Is surgical excision necessary for atypical ductal hyperplasia of the breast diagnosed by Mammotome?

BACKGROUND

Core biopsy findings of atypical ductal hyperplasia (ADH) underestimates the diagnosis of malignancy by 18% to 88%. Using the Mammotome biopsy technique, more accurate assessment of the lesion is possible, making selective excision of these lesions a consideration.

METHODS

The records of 62 patients who were found to have ADH at Mammotome biopsy and subsequently underwent excision of the lesion were reviewed. Patient data were statistically analyzed for predictors of malignancy at the time of surgical excision.

RESULTS

Of the 62 patients, 9 (15%) had malignancy at excision. Variables predicting for malignancy included markedly atypical hyperplasia and incomplete removal of calcifications at Mammotome biopsy, a previous contralateral breast cancer, and a family history of breast cancer, with a combined sensitivity of 100% and specificity of 80%.

CONCLUSIONS

Mild ADH found on Mammotome, not associated with a personal or family history of breast cancer, may not need excision if all calcifications have been removed.

Prediction of patient responses to antihypertensive drugs using genetic polymorphisms: investigation of renin-angiotensin system genes

OBJECTIVE

To investigate whether the M235T polymorphism of the angiotensinogen (AGT) gene and the insertion/deletion (I/D) polymorphism of the angiotensin-1 converting enzyme (ACE) gene predict blood pressure response to different antihypertensive agents.

DESIGN

Sixty-three patients with untreated essential hypertension were randomly assigned in a placebo-controlled crossover comparison to atenolol 50 mg once daily, lisinopril 10 mg once daily and nifedipine SR 20 mg twice daily, and the effect on blood pressure was assessed by ambulatory blood pressure monitoring (ABPM). In a further 44 patients, placebo-controlled ABPM data were available after treatment with a single agent (atenolol 50 mg once daily in 16 cases and lisinopril 10mg once daily in 28 cases). The change in systolic and diastolic blood pressure achieved by each agent was analysed for association with genotypes at the AGT and ACE gene loci.

METHODS

Polymerase chain reaction (PCR) amplification of genomic DNA from each individual was used to identify the I/D polymorphism of the ACE gene. The M235T polymorphism of the AGT gene was detected by Tth111I digestion of PCR product.

RESULTS

There was no significant association between response to any drug and either the AGT M235T or ACE I/D polymorphisms.

CONCLUSIONS

The large variability between individuals in the observed blood pressure response to these agents cannot be attributed to the polymorphisms analysed at the ACE and AGT loci.

Orbital-facial complications of sinusitis in children

Although complications of sinusitis in children have lessened remarkably since and advent of antibiotics, nevertheless they still occur. In a 25-year period at the Hospital for Sick Children, 6,770 patients with the diagnosis of sinusitis were reviewed and 159 of these had orbital-facial complications. Surgical intervention was necessary in 17 to prevent more serious complications. Although there were no deaths in non-malignant disease, two patients developed permanent optic atrophy, presumably because of delayed surgical drainage. On occasion, malignant disease may simulate inflammatory processes.

Tumors of the central nervous system studied by computed tomography and ultrasound

Intraoperative ultrasound (US) was compared to computed tomography (CT) in 41 intracranial and 6 spinal cord tumors. The studies correlated closely except for primary gliomas. Eight of the 22 primary intracranial gliomas (37%), including 1 low-grade and 7 anaplastic tumors, were larger and more extensive on US than on CT. Margins of non-enhanced primary astrocytomas were shown by US but not CT. Four anaplastic tumors (19%) exhibited echogenicity extending beyond the enhanced area. In 4 patients an enhanced lesion contained a lucent center which proved to be echogenic. Low-grade astrocytomas were relatively homogeneous on US, while anaplastic astrocytomas were more inhomogeneous. Cysts could be found in both types of astrocytomas and were often small and multiple. The echo pattern was not helpful in differentiating metastases from primary tumors, although all of them had sharp margins. Sonography of the central nervous system can provide valuable information about tumor morphology and margins.

Biochemical findings in sarcoidosis

The majority of patients with sarcoidosis in this large series have had a number of biochemical investigations performed. Abnormal calcium metabolism was demonstrated in 40% of the patients but permanent renal damage due to nephrocalcinosis as a result of persistent derangement of calcium metabolism was rare. Raised immunoglobulin levels were seen. Half the white and two-thirds of the West Indian patients had elevated IgG levels. Abnormal immunoglobulin levels carried no obvious diagnostic or prognostic significance. Raised alkaline phosphatase levels reflected space-occupying hepatic granulomas and occurred in 23% of patients. Serum angiotensin converting enzyme (SACE) was elevated in half the patients. The highest SACE activity was found in patients with severe parenchymal lung infiltration due to sarcoidosis, and the lowest levels in those with inactive disease or after successful management with steroid drugs. SACE levels were not significantly elevated in four other granulomatous conditions: Crohn's disease, primary biliary cirrhosis, Hodgkin's disease, and active tuberculosis.

Infantile gastroenteritis: a clinical study of reovirus-like agent infection

In a clinical study of 32 infants with symptoms from infections with the human reovirus-like agent (R.I.A.) identified by electron microscopy (E.M.) of faecal extracts, a fairly consistent clinical pattern was found in 30 who had a gastroenteritis-like illness. The disease was usually mild, affecting mainly infants less than 2 years and males more commonly than females. The incubation period appeared to be 48-72 hours; and the onset was sudden, often with vomiting in the first 1-2 days of the illness. Loose yellow-green offensive stools without blood or mucus developed after a variable time, and there was often accompanying fever. Severe dehydration and electrolyte inbalance were uncommon; and with standard treatment the illness was uncomplicated, usually lasting 5-8 days. These features resemble those of previously reported winter epidemics of infantile non-bacterial gastroenteritis, and it is suggested that these epidemics were due to R.L.A. 2 infants in whom R.L.A. was identified in the stool did not have a gastroenteritis-like illness although both had protracted diarrhoea.

Left ventricular hypertrophy in hypertensive patients is associated with abnormal rate adaptation of QT interval

OBJECTIVES

This study sought to examine whether the responses of the QT interval to changes in the heart rate were altered in left ventricular hypertrophy (LVH).

BACKGROUND

The QT interval has been shown to have a delayed adaptation to sudden changes in heart rate in normal subjects. Abnormalities in the adaptation of the QT interval to changes in the RR interval may facilitate the development of ventricular arrhythmias.

METHODS

Consecutive newly diagnosed hypertensive subjects, not taking any medications, were age and gender matched for LVH (n = 21) versus on LVH (n = 16). QT interval dynamics were analyzed under visual control using a validated algorithm with automatic QT measurements at the end of the T wave. A computerized Holter system was developed to study the QT interval response to changes in the RR interval. The adaptive response of the QT interval was measured as the ratio of the slope from 10% to 90% of the QT change relative to the RR interval change (dQT/dRR10-90). Steady state adaptation was also studied as the percent shortening and lengthening of the QT interval during acceleration and deceleration of heart rate.

RESULTS

The adaptive response of the QT interval measured as dQT/dRR10-90 was increased in the LVH group compared with that in the control subjects during both acceleration (0.33 +/- 0.06 vs. 0.18 +/- 0.02, p = 0.02) and deceleration phases (0.23 +/- 0.04 vs. 0.16 +/- 0.02, p = 0.03). In the LVH group, the percent lengthening of the QT interval was greater (7.6 +/- 0.7 vs. 5.1 +/- 0.2, p = 0.03), whereas the percent shortening was not significantly different (5.71 +/- 0.5 vs. 4.6 +/- 0.3, p = 0.43), than that in control subjects.

CONCLUSIONS

The QT interval response to changes in the RR interval is rapid and exaggerated in LVH. These abnormalities of the QT interval response demonstrate that there are altered repolarization dynamics in patients with LVH that may make them vulnerable to serious ventricular arrhythmias.

Predictors for optimal mobilization and subsequent engraftment of peripheral blood progenitor cells following intermediate dose cyclophosphamide and G-CSF

Fifty consecutive patients undergoing cyclophosphamide/G-CSF mobilization were studied for indicators predictive for adequate harvest (CD34+ cells > 2 x 10(6)/kg, CFU-GM > 1 x 10(5)/kg). Target yields following a single leukopheresis were achieved for 66% of patients (89% with no previous alkylation chemotherapy or radiotherapy). Previous alkylation therapy, radiotherapy and low collection day platelet count were predictive of poor collection yields. Following reinfusion, the median time to platelets > 20 x 10(9)/l (PLT > 20) was 10 days and to neutrophils > 500 x 10(6)/l (ANC > 500) was 13 days. Total CD34+ cells infused was predictive of early platelet engraftment. Previous radiotherapy was inversely predictive of neutrophil engraftment. For the majority of patients not exposed to alkylation therapy or radiotherapy, adequate progenitor cells can be collected following a single leukopheresis. In patients suitable for future autologous bone marrow transplantation it would seem appropriate to avoid or minimize radiotherapy and alkylation therapy exposure in the pre-collection period.

Optimal timing of doses of chenic acid in patients with gall stones

Sixteen patients with gall stones were treated with chenic acid (14-16 mg/kg/day) given at three different times in random order for one month each. Before treatment the mean (+/- SE of mean) cholesterol saturation index (SI) of fasting gall-bladder bile was 1.28 +/- 0.06. During bedtime administration of chenic acid the mean SI fell to 0.78 +/- 0.04, which was significantly lower than that obtained with administration in the morning (0.92 +/- 0.05) or with three divided doses at mealtimes (0.92 +/- 0.04). The bile remained supersaturated in seven patients when they received a single morning dose, in five patients when they received mealtime doses, but in only one patient when a single bedtime dose was given. There was no significant difference in side effects between the three different dose timings, or in the proportion of bile acids present in the bile as chenic acid. This enhanced effect obtained with bedtime administration may be due to the enterohepatic circulation of bile acids being maintained during overnight fasting.

Expression of CEA, CA125, CA19-9 and human milk fat globule membrane antigen in ovarian tumours

The expression of five different antigens in ovarian tumours was studied by means of an immunohistochemical test with anti-CEA, HMFG1 and HMFG2, NS19-9 and OC125 antibodies. Considerable variation was noted not only between different histological types and between tumours of one type but also between areas in a single tumour. HMFG1 and HMFG2 were the most reactive of all the antibodies; NS19-9 and OC125 were expressed by different populations of cells. It is concluded that specific combinations of antibodies are more effective both for the monitoring of ovarian cancer as well as for immunodiagnosis and treatment, than any single one used.

Subglottic stenosis of the larynx in the infant and child. Methods of management

This presentation is a ten-year retrospective study on all patients with proven subglottic stenosis admitted to the Department of Otolaryngology, Hospital for Sick Children, Toronto. Some of these patients have required no treatment, others one or two dilatations of the stenosis only; others tracheotomy only; some tracheotomy plus dilatations; some the Fearon-Cotton operation, and a few who had very extensive stenosis of the larynx and trachea, extensive reparative surgery. In this presentation, the authors describe the different types of management, and the results of treatment are assessed and compared.