A stable cell line carrying adenovirus-inducible rep and cap genes allows for infectivity titration of adeno-associated virus vectors

Adeno-associated virus (AAV) vectors are being developed for in vivo and ex vivo gene transfer to human cells. At present, widespread usage of AAV vectors is limited primarily by difficulties in generating recombinant virions on a scale sufficient for in-depth preclinical and clinical trials. However, recent work in several laboratories suggests that this technical obstacle should be overcome in the near future. As a result, it can be anticipated that the interest in AAV vectors will expand, Thus, it becomes important to develop assay systems that will permit accurate quantification of the infectivity of AAV vectors derived from a variety of sources. We have developed an assay using a cell line that expresses AAV helper functions (rep and cap) upon induction by adenovirus infection. This assay system is based on the replication of input rAAV genomes rather than transgene expression (transduction). Thus, infectivity titrations in this system yield an estimation of rAAV infectious particles irrespective of the promoter or transgene present in the vector genome. Moreover, this assay method is more sensitive than conventional methods being used in other laboratories.

Relationship of plasma leptin to plasma insulin and adiposity in normal weight and overweight women: effects of dietary fat content and sustained weight loss

Leptin, the product of the human homologue of the ob gene, which is defective in the obese (ob/ob) mouse, may be a humoral regulator of human adiposity. Plasma leptin concentrations were measured by RIA in 19 normal weight [body mass index (BMI) = 24.5 +/- 0.6 kg/m2] and 19 overweight to obese (BMI = 34.7 +/- 1.2 kg/m2) nondiabetic postmenopausal women on sequential controlled weight-maintaining diets containing 31%, 23%, and 14% of energy as fat, each for 4-6 weeks. Thereafter, the subjects ate a very low fat diet (< 15%) ad libitum; plasma leptin and insulin concentrations, BMI, percent body fat (%BF), and resting energy expenditure were determined after 6 and 8 months. Absolute and adiposity-corrected plasma leptin levels were higher in overweight/obese women (37.7 +/- 3.5 ng/mL; 1.01 +/- 0.07 ng.mL-1.%BF-1) than in normal weight women (16.9 +/- 2.2 ng/mL; 0.57 +/- 0.06 ng.mL-1.%BF-1, both P < 0.005 vs. obese), but were not different between the 31%, 23%, and 14% fat diets when body weight was stable. Plasma leptin was highly correlated with BMI (r = 0.81, P < 0.0001), %BF (r = 0.80, P < 0.0001), and fasting plasma insulin (r = 0.61, P < 0.0001). After 8 months on the ad libitum low fat diet, the women had lost an average of 6.9 +/- 1.0% of body mass (-2.0 +/- 0.3 kg/m2, P < 0.0001). In 15 subjects who lost more than 7% of body mass (-12.3 +/- 1.0%), plasma leptin concentrations decreased (-9.6 +/- 1.9 ng/mL, P < 0.0005), and the decrease of plasma leptin per change of adiposity (delta leptin/delta %BF) was greater in overweight/obese women (3.6 +/- 0.5) than in normal weight women (0.9 +/- 0.4, P < 0.01 vs. obese). In 18 other subjects who lost less than 7% of body mass (-2.7 +/- 0.6%), plasma leptin was unchanged (+1.4 +/- 1.4 ng/mL). Overall, the change of plasma leptin was significantly correlated with change of BMI (r = 0.43, P < 0.02), the change of %BF (r = 0.49, P < 0.005), the change of resting energy expenditure (r = 0.40, P < 0.02), and with the change of plasma insulin independently of changes of body adiposity (r = 0.45, P < 0.01). We conclude that plasma leptin concentrations are: 1) not affected by dietary fat content per se; 2) highly correlated with BMI, %BF, and plasma insulin in both overweight/obese and normal weight women; 3) decreased in parallel with plasma insulin after sustained weight loss; and 4) decreased more in overweight/obese than in normal weight women.

Loss of functional KATP channels in pancreatic beta-cells causes persistent hyperinsulinemic hypoglycemia of infancy

Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) is a disorder of childhood associated with inappropriate hypersecretion of insulin by the pancreas. The pathogenesis of the condition has hitherto remained controversial. We show here that insulin-secreting cells from a homogeneous group of five infants with PHHI lack ATP-sensitive K+ channel (KATP) activity. As a consequence, PHHI beta-cells are spontaneously electrically active with high basal cytosolic Ca2+ concentrations due to Ca2+ influx. Our findings define the pathogenesis of this disease as a novel K+ channel disorder.

Long-term results of unilateral neck exploration for preoperatively localized nonfamilial parathyroid adenomas

BACKGROUND

Unilateral neck exploration for sporadic parathyroid adenomas remains a contentious policy. The morbidity is lower than for bilateral surgery, but the long-term outcome may be inferior.

METHODS

The results of a policy of unilateral neck exploration for primary hyperparathyroidism based on preoperative localization are reviewed.

RESULTS

Over a 10-year period, 89 patients were operated on, 57 undergoing unilateral neck exploration. Unilateral neck exploration significantly reduced operative time (P < 0.0001) and postoperative hypocalcaemia (P = 0.021). Over a mean biochemical follow-up of 38 months, recurrent hypercalcaemia occurred in 6% of patients, including 3.5% of those undergoing unilateral neck exploration, an additional 10% of patients were normocalcaemic with an inappropriately elevated parathormone level.

CONCLUSIONS

A policy of unilateral neck exploration can achieve comparable long-term results to more extensive bilateral surgery.

Influence of different collagenase solvents and timing of their delivery on porcine islet isolation

Methods to minimize the effect of cold ischaemia on porcine islet isolation were investigated. Forty pancreata were randomized to intraductal collagenase delivery in University of Wisconsin solution (UW) or Hanks balanced salt solution (HBSS) (control) both before and after 65 min of cold pancreas storage. Collagenase was also administered in a specially designed cold storage solution (University of Leicester solution, ULEIC), before cold storage. Median islet yield was significantly greater if the pancreas was distended with collagenase in either UW (21524 islet equivalents (IEQ) per g) or ULEIC (19814 IEQ/g) before cold storage, compared with that after distension with HBSS (6924 IEQ/g) following cold storage (P < 0.05). Islet fragmentation, islet purification and glucose-stimulated insulin release were not significantly different after collagenase delivery in either UW or ULEIC compared with those after administration in HBSS. It is concluded that porcine islet yields can be improved significantly by intraductal collagenase administration in either UW or ULEIC immediately after excision of the pancreas.

Airway smooth muscle in asthma

One of the factors that may contribute to the exaggerated airway narrowing in asthma is an abnormality of the airway smooth muscle. This abnormality could take the form of an increase in the amount of muscle or an alteration in its pharmacological reactivity. The former could be due to either hypertrophy (an increase in individual muscle cell size) or hyperplasia (an increase in cell number). Changes in pharmacological reactivity that could be relevant to altered airway calibre could result from an increase in contraction or alternatively, a decrease in relaxation. Based on available evidence, the increase in smooth muscle bulk is probably the consequence of both hyperplasia and hypertrophy and several growth factors, inflammatory mediators and cytokines have been implicated. Asthmatic airway tissue is rarely available for in vitro pharmacological studies and evidence for enhanced contraction is limited. Recent evidence suggests that an abnormality in beta adrenoceptor function may contribute to impairment of relaxation, but further work needs to be done. Passive sensitization of non-asthmatic airways in vitro provides a good model for the study of the mechanisms underlying airway hyperresponsiveness, and will be the subject of more intensive study in the future.

Successful treatment of HTLV-1-associated acute adult T-cell leukaemia lymphoma by allogeneic bone marrow transplantation

HTLV-1-associated acute adult T-cell leukaemia-lymphoma (ATL) is a highly aggressive malignant disorder with a median survival of 6 months or less. We describe an Afro-Caribbean female with very poor prognosis ATL who underwent chemotherapy with a 4 d infusion schedule of cyclophosphamide, doxorubicin and etoposide, followed by successful allogeneic bone marrow transplantation (BMT) from her HTLV-1-negative histocompatible sister. The patient remains in complete remission 23 months after BMT and has 100% donor haemopoiesis with no evidence of HTLV-1 infection on PCR testing. We suggest that allo-BMT can prolong disease free survival or may even be curative in HTLV patients.

Predominately glucocorticoid agonist actions of RU-486 in young specific-pathogen-free Zucker rats

Previous studies have demonstrated antiglucocorticoid actions for the progesterone receptor antagonist RU-486. In one study, daily administration of this drug for 2 wk decreased food intake (FI) and body weight gain (delta BW) in obese, but not lean, conventionally housed 5-wk-old female Zucker rats. We recently found that 2-wk administration of RU-486 attenuated delta BW in lean but not obese 12-wk-old male Zucker rats without affecting FI. To examine the actions of RU-486 and its effects on FI and delta BW in young (5 wk old) specific-pathogen-free (SPF) male and female Zucker rats, RU-486 was administered at 30 mg.kg-1.day-1 subcutaneously for 14 days. RU-486 did not affect FI in obese or lean male or female rats. RU-486 increased adrenal weight (P < 0.05) overall and in lean female rats and modestly decreased inguinal fat weight overall and in obese female rats (P < 0.01), suggesting some antiglucocorticoid activity in these animals. However, RU-486 also decreased thymus weight by 18-31% (P < 0.0001), increased plasma glucose by 10-16 mg/dl (P < 0.002), and increased plasma insulin by 47% in obese male rats (P < 0.028), demonstrating glucocorticoid agonist actions for the drug. Plasma corticosterone (B) and adrenocorticotropic hormone (ACTH) were elevated in vehicle-treated obese female and male rats by 150-360% (P < 0.0025) and 32-38% (P < 0.05), respectively, compared with lean rats. RU-486 treatment lowered the elevated plasma B and ACTH levels in obese female and male rats (both P < 0.02 vs. vehicle), a glucocorticoid agonist effect. We conclude that in young SPF Zucker rats 1) RU-486 administration does not alter FI or delta BW, 2) RU-486 has predominately glucocorticoid agonist actions in several tissues, 3) obese animals have increased hypothalamic-pituitary-adrenal (HPA) axis activity (plasma B and ACTH), and 4) RU-486 administration suppresses the HPA axis in obese rats.

Production of glycosylated heparin-binding EGF-like growth factor in HeLa cells using vaccinia virus

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a 22-kDa, O-glycosylated protein. Because recombinant expression systems permitting a detailed analysis of the functional significance of HB-EGF glycosylation have not been described, a recombinant vaccinia virus designed to express HB-EGF was generated by homologous recombination of an intermediate plasmid vector carrying the HB-EGF cDNA and the genome of vaccinia virus and was used to infect HeLa cells. Production of immunoreactive HB-EGF was confirmed by immunofluorescence and radioimmunoprecipitation analysis. Furthermore, the expressed protein was shown to be a secreted, biologically active protein by radioreceptor and DNA synthesis assays of HeLa cell conditioned medium. The recombinant protein was purified from the conditioned medium using heparin-affinity fast protein liquid chromatography followed by C4 reverse-phase high-performance liquid chromatography (RP-HPLC). SDS-PAGE and Western blotting of the RP-HPLC-purified product showed an immunoreactive HB-EGF protein of approximately 22 kDa that was decreased to a 14-kDa protein by treatment with O-glycanase. Amino acid sequencing revealed an N-terminus that was characteristic of native, glycosylated HB-EGF. Interestingly, a Thr residue that is a putative site of O-linked glycosylation failed to be resolved. This system provides a valuable method for evaluating the role of glycosylation in HB-EGF function(s) as well as addressing other questions concerning HB-EGF structure-function relationships.

Passive immune globulin therapy in the SIV/macaque model: early intervention can alter disease profile

One of the major questions in AIDS is the role that the host immune system and the virus play in the dynamics of infection and the development of AIDS in an infected individual. In order to test the role of antibody in controlling viral infection, high-dose SIV-immune globulin was passively transferred to infected macaques early in infection. Immune globulin purified from the plasma of an SIV-infected long-term non-progressor macaque (SIVIG) or a pool of normal immune globulin (normal Ig) was infused into SIVsmE660-infected macaques (170 mg/kg) at one and fourteen days post infection. Animals were monitored for SIV-specific antibodies, viremia, plasma antigenemia, and clinical course. All animals were infected by SIV. At 16 months post infection, five macaques in the combined control groups have been euthanized, one as a rapid progressor with debilitating disease at 20 weeks post infection. Four macaques from the comparison groups have signs of AIDS, accompanied by high and increasing levels of virus and p27 antigenemia. One of the ten control animals had a very low virus load in plasma and peripheral blood and lymph node mononuclear cells at all times tested and has remained disease-free. In the SIVIG treatment group, two macaques were euthanized at 18-20 weeks due to AIDS, rapid progressors to disease. Three macaques in the SIVIG group had an initial high level of virus in plasma, peripheral blood mononuclear cells (PBMC), and lymph node mononuclear cells (LNMC), which dropped to baseline at 6 weeks post infection and has remained very low or negative for 16 months, a disease profile which has not been observed in untreated animals in this model to date. These macaques have remained clinically healthy. The sixth treated animal is also healthy, with very low virus burden that is detectable only by nested set polymerase chain reaction (PCR). All SIVIG-treated macaques had no detectable p27 plasma antigenemia for the first 10 weeks of infection, demonstrating that the IgG effectively complexed with the virus. The immunological correlates in the treated animals include development of de novo virus-specific antibodies and/or cytotoxic T cell (CTL), both of which are hallmarks of long term non-progressors. The two SIVIG-treated macaques that progress to disease rapidly had no detectable de novo humoral immune responses, as is often seen in rapid HIV disease in humans. Envelope-specific and virus neutralizing antibodies alone were not sufficient to prevent disease progression, as the plasma of both non-progressors as well as progressors had high titers of envelope-specific and neutralizing antibodies against SIVsmE660. Poor clinical prognosis was associated with moderate to high and increasing virus loads in plasma, PBMC, and lymph nodes. Good clinical prognosis correlated with low or undetectable post acute viremia in the peripheral blood and lymph nodes. We hypothesize that SIVIG reduced the spread of virus by eliminating or reducing plasma virus through immune complexes during the first four to 8 weeks of infection and then maintaining this low level of viremia until the host immune response was capable of virus control. Reduction of virus burden early in infection by passive IgG can alter disease outcome in SIV infection of macaques. Modifications of this strategy may lead to effective early treatment of HIV-1 infection in humans.

Does the disease state influence the responsiveness of human airways studied in vitro?

Human airway tissue has been used in vitro to study mechanisms of airway disease. However, there has never been a comprehensive study that has looked at the influence of disease on the subsequent in vitro responsiveness of human airways. In this study, we obtained airway tissue from patients who were undergoing resection of the lung for carcinoma. We then compared the airway responsiveness in these tissues and in tissues from patients who had undergone lung transplantation for alpha-1-antitrypsin deficiency, emphysema, or cystic fibrosis with the responsiveness in tissues obtained from donor lungs, i.e., nondiseased. When the relationships between concentration and response were compared, we found that for histamine, electrical field stimulation, levcromakalim, and isoproterenol similar responses could be expected in tissues obtained from all the sources studied. This was not true for acetylcholine in that there were significantly lower responses in tissues from patients with alpha-1-antitrypsin deficiency (P = 0.02; n = 9) or from patients having a lung resected for carcinoma (P = 0.01; n = 6) compared with that of the nondiseased group (n = 6). Similarly, for carbachol, the responses were significantly lower in the alpha-1-antitrypsin deficiency group (P = 0.001; n = 10) and in specimens resected for carcinoma (P = 0.001; n = 6) than in the nondiseased group (n = 9). We conclude that, apart from acetylcholine and carbachol, contractile and relaxant agonists give similar responses when used in human airway tissues from various sources. Our results highlight the importance of stating the source of tissue when human airways are to be studied.

Ionic control of beta cell function in nesidioblastosis. A possible therapeutic role for calcium channel blockade

A preterm female infant presented with intractable hypoglycaemia within 10 minutes of delivery. Normoglycaemia could be maintained only by the intravenous infusion of glucose at a rate of 20-22 mg/kg/min. Persistent hyperinsulinaemic hypoglycaemia of infancy was diagnosed from an inappropriately raised plasma insulin concentration (33 mU/l) at the time of hypoglycaemia (blood glucose < 0.5 mmol/l). Medical treatment with glucagon, somatostatin, and diazoxide led to only a modest reduction in the intravenous glucose requirement; a 95% pancreatectomy was performed and histological 'nesidioblastosis' confirmed. In vitro electrophysiological studies using patch clamp techniques on isolated pancreatic beta cells characterised the ionic basis for insulin secretion in nesidioblastosis. The beta cells were depolarised in low ambient glucose concentrations with persistently firing action potentials; these were blocked reversibly by the calcium channel blocking agent verapamil. Persistent postoperative hyperinsulinaemic hypoglycaemia was treated with oral nifedipine. This increased median blood glucose concentrations from 3.5 to 4.8 mmol/l and increased in duration the child's tolerance to fasting from 3 to 10.5 hours. These data allude to an abnormality in the ionic control of insulin release in nesidioblastosis and offer a new logical approach to treatment which requires further evaluation.

In vivo MRI characteristics of lipoma arborescens utilizing fat suppression and contrast administration

Lipoma arborescens or villous lipomatous proliferation of the synovium is a rare lesion. We describe the in vivo imaging characteristics of lipoma arborescens of the knee utilizing fat suppression techniques and contrast medium administration. As expected, the lesion demonstrated signal loss when utilizing fat suppression. In addition, no contrast enhancement was noted. When a synovial process demonstrates isointensity with subcutaneous fat on all pulse sequences and no contrast enhancement, lipoma arborescens should be the primary diagnosis consideration.

Selection criteria for preoperative endoscopic retrograde cholangiopancreatography in the laparoscopic era

BACKGROUND

Indicators for cholangiography were originally designed to select patients at risk for common bile duct (CBD) stones for intraoperative cholangiography.

OBJECTIVE

To refine these criteria to apply to the much more invasive procedure of preoperative endoscopic retrograde cholangiopancreatography (ERCP).

DESIGN

Retrospective review of selection criteria for ERCP in consecutive patients referred over 18 months following the introduction of laparoscopic cholecystectomy.

SETTING

Two ERCP units in adjacent teaching hospitals.

PATIENTS

Three hundred seventeen patients with gallstones and in situ gallbladders.

INTERVENTION

Common bile duct imaging at ERCP.

MAIN OUTCOME MEASURES

Abnormalities justifying ERCP.

RESULTS

Abnormalities justifying ERCP were found in 66% of patients. This group differed significantly from those with normal ducts, with more being referred with abnormal results of all liver function tests (P < .001), jaundice (P < = .001), a dilated CBD on ultrasound (P < .001), or CBD stones on ultrasound (P < .001). On the other hand, patients with normal ducts were significantly more likely to have been referred with pancreatitis (P = .003) or elevated results of individual liver function tests (P < .001). A logistic regression model using age, presence of jaundice at ERCP, levels of alkaline phosphatase and albumin, and ultrasonography showing dilated ducts or visible CBD stones was found to have a specificity of 75% and a sensitivity of 89%. Past pancreatitis or elevated results of individual liver function tests were not predictive factors.

CONCLUSION

The use of such a model rather than individual criteria would improve the selection of patients for preoperative ERCP, optimizing its role in the laparoscopic era.

Cervical cancer survival in a high risk urban population

BACKGROUND

Cervical cancer remains an important public health problem, particularly for the urban minority population. To the authors' knowledge, determinants of cervical cancer survival have not been studied in this high risk population.

METHODS

This study included all 158 women diagnosed and treated for invasive cervical cancer from January 1, 1986, through December 31, 1992, at the Grady Memorial Hospital and Clinics (Atlanta, GA). Medical records were abstracted to determine age at diagnosis, race, International Federation of Gynecology and Obstetrics (FIGO) clinical stage, treatment, and survival. Pathologic material was reviewed to confirm the diagnosis.

RESULTS

Most patients (80%) were African American, and the stage distribution was similar for African American and white patients. Sixty-six (42%) had FIGO Stage I disease; 50%, Stage II or III; and 8%, Stage IV. Four-year actuarial survival differed significantly according to clinical stage (Ia = 94%, Ib = 79%, II = 39%, III = 26%, IV = 0%). Overall survival was lower for patients with glandular carcinomas than for those with squamous cell carcinomas (26% vs. 55%, P = 0.09). This difference was almost entirely due to increased mortality in patients with Stage Ib adenocarcinomas (53% vs. 88% for squamous cell carcinoma, Stage Ib, P = 0.03).

CONCLUSIONS

The major prognostic markers for cervical cancer survival in this high risk patient population were clinical stage and histology, factors identical to those identified for other populations.

Puerperal cerebral venous thrombosis associated with decreased free protein S: a case report

BACKGROUND

Cerebral venous thrombosis is a rare event with multiple risk factors. This condition can be associated with a hypercoagulable state, such as that seen with dysfunctional or decreased plasma protein C and protein S. Both plasma proteins are naturally occurring, vitamin K-dependent anticoagulants that are important for regulation of the clotting cascade.

CASE

A postpartum patient presented with complaints of a severe headache and hypertension and later developed status epilepticus. She was found to have superior sagittal sinus and right internal jugular vein thrombosis and protein S deficiency.

CONCLUSION

The combination of protein S deficiency and the further reduction due to pregnancy may enhance the risk of major thrombotic episodes in the peripartum period.

Flow cytometry in diagnosis and management of large fetomaternal haemorrhage

AIMS

To evaluate an indirect immunofluorescence flow cytometry technique in a series of patients with large fetomaternal haemorrhage (FMH).

METHODS

Patient samples identified by Kleihauer testing in local laboratories as having FMH > 4 ml were sent for flow cytometric analysis. In a proportion of cases the mothers received anti-D immunoglobulin prophylaxis according to the flow cytometer estimate of FMH volume.

RESULTS

Forty three cases of FMH were studied prospectively. The correlation between Kleihauer and flow cytometry results was poor. In 38 (88%) cases the size of FMH quantitated by flow cytometry was lower than that estimated using the Kleihauer technique. In 13 (30%) cases no Rh D immunoglobulin positive cells were detected by flow cytometry. Centralised review of the original Kleihauer films using a calibrated microscope resulted in improved, but still suboptimal correlation with flow cytometry results. In 15 cases anti-D immunoglobulin was given according to the flow cytometer estimation of FMH size, resulting in a 58% reduction in the amount of anti-D immunoglobulin given. None of the patients were immunised when tested six months later.

CONCLUSIONS

Flow cytometry is helpful for the accurate quantitation and management of patients with large FMH and in cases where the presence of maternal haemoglobin F containing cells renders the Kleihauer technique inaccurate. Worthwhile reductions in the use of anti-D immunoglobulin can be achieved.

Factors predicting outcome after selective ERCP in the laparoscopic era

This study assessed the outcome of 342 patients with in situ gallbladders undergoing ERCP for suspected choledocholithiasis. The result of ERCP was found to play a significant role (P < 0.0001) in determining whether patients were subsequently managed conservatively (n = 152) or underwent either laparoscopic (n = 110) or open (n = 80) surgery. Those undergoing laparoscopic surgery were noted to be younger (P = 0.0001) and were less likely to be jaundiced (P = 0.0015) or have CBD stones at ERCP (P = 0.0295). In 28 patients with CBD stones remaining after ERCP, pre- rather than postoperative timing of ERCP prevented a potential second operation. The current success rate of 85% in clearing CBD stones at ERCP cannot support a routine policy of intraoperative cholangiography followed by postoperative ERCP.

Heparin and PGE2 inhibit DNA synthesis in human airway smooth muscle cells in culture

An increase in the bulk of the airway smooth muscle is a characteristic of asthma. Much of the research investigating the mechanisms of this increase in muscle has focused on mediators that are mitogenic for smooth muscle, while relatively few studies have focused on mediators inhibiting mitogenesis. In this study we have examined the effects of two mediators proposed as regulators of smooth muscle proliferation, namely heparin and prostaglandin (PG) E2, on human airway smooth muscle cells in culture stimulated with 1, 2.5, 5, and 10% fetal bovine serum (FBS) and platelet-derived growth factor AB (PDGF), 50 ng/ml. PGE2 had a biphasic effect on DNA synthesis in the presence of 1% FBS, with 10(-6) M causing inhibition and 10(-7) M causing an increase in DNA synthesis. PGE2 caused inhibition of DNA synthesis in the presence of 2.5, 5, and 10% FBS. Heparin (10 and 100 U/ml) caused an inhibition of DNA synthesis induced by 1% FBS, while 100 U/ml inhibited DNA synthesis induced by 5 and 10% FBS. PGE2 (10(-8), 10(-7), and 10(-6) M) inhibited the DNA synthesis induced by PDGF, while heparin (1, 10, and 100 U/ml) had no effect. These results indicate that both PGE2 and heparin may have a role in the control of human airway smooth muscle cell growth.