Use of propranolol in infantile haemangioma among Chinese children

OBJECTIVE

To describe the use of propranolol as first-line treatment or as single therapy to control the proliferating phase of infantile haemangioma in Chinese children.

DESIGN

Retrospective study.

SETTING

Regional hospital, Hong Kong.

PATIENTS

Children 3 years old or younger with facial haemangioma who took oral propranolol between 1 December 2008 and 1 December 2009.

RESULTS

There were 12 such patients, all of whom underwent prior clinical evaluation before starting the treatment. Ten patients had a solitary facial haemangioma and two had multiple haemangiomas. The mean age of symptom onset was 12 days. The mean age for starting propranolol treatment was 7 months, and in all cases a clinical response was observed within 7 days. Five (41%) of the patients had complete resolution 2 to 6 months after starting medication, at which time they were 5 to 12 months old. Two of them had a recurrence of the haemangioma within 8 weeks of stopping the drug, but responded to a second treatment course. In these two patients, the propranolol dosage had been tailed down rapidly and the therapy was of a shorter duration than in those without recurrence. The remaining seven patients are still taking propranolol and responding satisfactorily. Hypotension was observed in two patients, one of whom tolerated a lower dose and in the other, therapy was reinitiated at her older age. No serious side-effect was encountered in the remaining patients.

CONCLUSION

Propranolol was useful as first-line or single-agent treatment of facial infantile haemangioma in Chinese children, and gave rise to minimal side-effects. Although recurrence of infantile haemangioma occurred after propranolol was tailed off rapidly after a relatively short duration, an optimal treatment duration and tapering schedule has not yet been defined. Nevertheless, patients responded well to second courses of propranolol therapy.

High-yield expression of fully bioactive N-terminal parathyroid hormone analog in Escherichia coli

A fully active analog of human parathyroid hormone (hPTH) has been produced by recombinant expression in Escherichia coli. Initially, a nucleotide sequence encoding hPTH(1-34)-Asp-Pro was ligated to a proinsulin gene in the plasmid pUC8, for the eventual expression of a fusion protein of 137 amino acids. Unexpectedly, the proinsulin gene and 340 bp downstream were deleted by an unknown mechanism during transformation of the E. coli. This resulted in a new plasmid encoding a small (72-amino acid) fusion product of hPTH(1-34)-Asp35-Pro36-X, where X is a 36-residue "arbitrary" downstream sequence of pUC8. The fusion product was efficiently expressed and the hPTH analog, [Asp35]hPTH-(1-35), was readily released by acid cleavage, with a yield of 100 mg/L. This analog had an effective concentration for half-maximal adenylyl cyclase stimulation (EC50) in rat osteosarcoma cells of 14 nM, which was identical to that for hPTH-(1-34). In the ovariectomized rat model of osteoporosis, [Asp35]hPTH-(1-35) was fully active as a bone anabolic agent.

Expression of Trichoderma reesei and Trichoderma viride xylanases in Escherichia coli

Synthetic genes encoding the 190 amino acid Trichoderma reesei xylanase II (TrX) and the closely related Trichoderma viride xylanases have been synthesized in a two-step procedure. Initially, a partial gene encoding amino acids 92-190 was constructed in fusion with the N-terminal half of the Bacillus circulans xylanase (BcX). The remaining BcX gene sequence was replaced during the assembly of the coding sequence for amino acids 1-91. Expression of the synthetic genes in Escherichia coli yielded recombinant xylanases with specific activity generally identical with the natural TrX. However, the recombinant TrX showed thermostability and temperature optimum lower than those of the natural TrX, thus indicating that the posttranslational modifications of the latter in its fungal host are essential to its greater stability. A mutation N19K further decreased the thermostability of the recombinant TrX.

Effect of base-mismatch in the cohesive ends of oligonucleotide in gene cloning

The tolerance of mismatched nucleotides between the cohesive ends of insert and target DNAs in gene cloning has been investigated. An oligonucleotide duplex with a cohesive end GGCC-5' or variation was ligated to the 5'-CCGG end of a linearized plasmid. The ligation mixture was used in the transformation of E. coli. A single-base mismatch, such as 5'-CCGG/AGCC-, GACC-, GGAC- or GGCA-5' (mismatch underlined), was well tolerated in the cloning of the oligonucleotide duplex, with efficiency lower than the fully complementary ends. Double-base mismatch 5'-CCGG/AACC- or GGAA-5' resulted in further decrease of cloning efficiency. Via a similar approach, a tetracycline resistance gene was successfully inserted into a pUC-type plasmid.

Overexpression of the Bacillus subtilis and circulans xylanases in Escherichia coli

An efficient expression system for a low-molecular mass xylanase in Escherichia coli has been developed. A gene encoding the mature Bacillus circulans (Bc) xylanase was designed to imitate the frequency of degenerate codons used in E. coli. Appropriate degenerate codons were used to create multiple unique restriction sites for future mutagenesis studies. The synthetic gene was constructed in two stages, both involving ligation of overlapping oligonucleotides. The synthetic Bc gene was then converted to a Bacillus subtilis (Bs) xylanase gene via a single codon substitution (Thr147Ser). The plasmids containing both synthetic genes were further modified for the direct expression in E. coli. Under the control of the lac promoter, recombinant xylanase has been produced at levels as high as 300 mg/liter in soluble form in the cytoplasm. This efficiency represented a dramatic improvement over all previous attempts involving the expression of the natural genes, with the xylanase being secreted in those cases. Characterization of our gene products indicated that the purified recombinant product was correctly processed and enzymatically active.

Internal ribosome-binding site directs expression of parathyroid hormone analogue (8-84) in Escherichia coli

Expression of the human parathyroid hormone (PTH) gene in E. coli yielded intact PTH and PTH-(8-84). To determine if PTH-(8-84) is the result of a competing translation initiated from methionine codon-8 or degradation of the intact PTH, twelve new gene constructs with or without an internal ribosome-binding site (iRBS) in the PTH-(1-5) region were prepared via substitution with degenerate codons. Expression of constructs without iRBS produced only intact PTH. Constructs with weak iRBS, including one that resembles the cDNA sequence, yielded PTH-(8-84) as a minor product. In contrast, constructs with strong iRBS produced predominantly or exclusively this shorter analogue.

Evaluation of the probability of spontaneous transfer of drug resistance between cells in culture

Coculture of two different cell lines in monolayer or spheroids was used to investigate the spontaneous transfer of dominant genes determining drug resistance. MGH-U1 human bladder cancer cells (ouabain-sensitive, mitomycin C-resistant) were cocultured with UV-20 cells (a subline of Chinese hamster ovary cells which is ouabain-resistant and mitomycin C-sensitive). We investigated the possible transfer of mitomycin-C resistance from human to rodent cells by selection in both ouabain and mitomycin C. Regardless of coculture conditions, the frequency of surviving cells was at a similar level to that expected from studies of cell survival when cells were cultured alone. We found no evidence of spontaneous transfer of drug resistance between the two cell lines.

Effect of transient hypoxia on sensitivity to doxorubicin in human and murine cell lines

Overreplication of DNA associated with gene amplification and drug resistance has been reported to occur after transient hypoxia of rodent cells. Because oxygen levels fluctuate in solid tumors, clinical drug resistance might be stimulated by this mechanism. We have therefore studied the effect of transient hypoxia on sensitivity to doxorubicin in human and murine cell lines. Exposure to hypoxia led to a decreased rate of cell proliferation, and most of the observed changes in sensitivity to doxorubicin were consistent with cell cycle-dependent cytotoxicity of this drug. After transient hypoxia, about 10% of the murine cells (EMT6/Ro and KHT-LP1) contained greater than four times the haploid DNA content (greater than 4C DNA), but only 0%-5% of the human cells (MGH-U1, A549, and Hey) had greater than 4C DNA content. Murine cells that had been exposed to hypoxia and reoxygenation, and which had greater than 4C DNA content, were separated by flow cytometry. For KHT-LP1 cells, but not for EMT6/Ro cells, this subpopulation was found to be more resistant to doxorubicin than the subpopulation with less than 4C DNA content and the aerobic control. When resistant KHT-LP1 clones were expanded in the presence of doxorubicin, six of six clones showed amplification of the P-glycoprotein gene family. The ability and efficiency of hypoxia to induce DNA overreplication, gene amplification, and drug resistance appears to be cell-line dependent.

Flow cytometric analysis of doxorubicin accumulation in cells from human and rodent cell lines

The correlation between intracellular accumulation of doxorubicin (DOX) and drug cytotoxicity was studied in cells from seven cell lines of rodent and human origin. We used three Chinese hamster ovary cell lines (AuxB1, CHRC5, and UV20), two murine tumor cell lines (KHT-LP1 and EMT6/Ro), and two human tumor cell lines (MGH-U1 and DLD-1). Intracellular DOX was measured by its fluorescence intensity with flow cytometry, and drug cytotoxicity was quantified with clonogenic assays. When data for all of the cell lines were combined, cell killing was correlated with the intracellular concentration of DOX (r = -.88). For the cell line AuxB1 and its DOX-resistant subline CHRC5, in which cells express high levels of P-glycoprotein, the relationship between cell survival and the intracellular concentration of DOX was stronger than that for the other cell lines. These results suggest that differences in intracellular accumulation of DOX account for much of the heterogeneity in response to the drug in cells from different cell lines, although additional mechanisms also contribute to variation in drug sensitivity. Flow cytometric analysis of intracellular DOX fluorescence is a simple assay that should be tested in cells from human tumors as a possible predictor of tumor response. For a given cell line, this technique also provides a rapid way to monitor the development of drug resistance after multiple courses of chemotherapy.

Tumour response to chemotherapy in animals that have been treated with the same drugs prior to tumour implantation: a model for studying host effects on apparent drug resistance

The outcome of cancer chemotherapy is determined by an interplay of multiple factors between the host, the tumour, and the drugs administered. Most studies have emphasised the development or selection of drug resistant tumour cells. However, repeated drug treatment of the host may lead to changes (e.g. in pharmacokinetics, host defences, etc.) which can influence the subsequent response of the tumour. In this study, we present a model to investigate the role of the host in the development of drug resistance. A drug is administered repeatedly to animals prior to tumour implantation, and tumour response is then evaluated following treatment with the same drug in pretreated and control animals. To illustrate the method, cyclophosphamide was administered weekly for 4 weeks to C3H mice before implantation of the KHT tumour. Tumour growth delay was then compared after one further treatment of cyclophosphamide in this group of animals to that in control mice which had not received the cyclophosphamide pretreatment. Our results indicate that cyclophosphamide produces only a small effect on the host in this system, but the model is a potentially useful one to investigate the contribution of the host in the acquisition of drug resistance.

Nutrient modification of proliferation and radiation response in EMT6/Ro spheroids

The effects of external nutrients on the growth and radiation response of EMT6/Ro spheroids were studied by maintaining spheroids in media with different concentrations of glucose, amino acids, and vitamins. Compared to spheroids grown in normal glucose concentration (5.5 mM), spheroids grown in higher glucose media (24.8 mM), demonstrated no difference in initial volume doubling time, clonogenicity, number of proliferating cells, or cell cycle distributions. However, histology sections revealed that, spheroids grown in higher glucose concentration had a thicker viable rim than spheroids grown in normal glucose media. Two-step acridine orange staining and dual parameter flow cytometric analysis, in addition to continuous [3H]-thymidine labeling techniques, showed that spheroids grown in higher glucose had 2 to 3 times the fraction of quiescent cells, when compared to normal glucose spheroids. When irradiated in ice to reoxygenate, the Do's were similar in the normal and the higher glucose spheroids, but the Dq's were reduced in the higher glucose spheroids in the presence of increased amino acids and vitamins. When irradiated in air at 37 degrees C, spheroids grown in the higher glucose media were more sensitive (decreased Do), and had a smaller hypoxic fraction than when grown in normal glucose media. For spheroids grown in the same glucose concentrations but increased concentrations of amino acids and vitamins, there was generally an increased Do under all irradiation conditions. Some of these differences in radiation sensitivity could be correlated to differences in cellular glutathione levels of these spheroid cells.

Radiation response of proliferating and quiescent subpopulations isolated from multicellular spheroids

Two subpopulations enriched in cells with a G1-like content of DNA were isolated from EMT6/Ro spheroids using centrifugal elutriation. The techniques of two-step acridine orange staining followed by flow cytometry, and continuous [3H]-thymidine labelling agreed qualitatively that one of these subpopulations predominantly consisted of proliferating G1 cells, while the other contained about four times more quiescent G0/G1 cells. These two subpopulations had similar median cell volumes and DNA contents, but the cell volume distributions were different. The clonogenicity was greater in the 'proliferating' subpopulation than the 'quiescent' subpopulation. When cell number seeded was corrected for viability, regrowth studies showed that there was a longer time (25 h) for the 'quiescent' subpopulation than the 'proliferating' subpopulation (10 h) before any increase in cell number was observed. In addition, relative to the 'proliferating' cells, the 'quiescent' cells were more sensitive when exposed to 137Cs gamma-ray radiation. The D0's were similar between the two subpopulations (D0 = 1.6 Gy and 1.8 Gy for the 'proliferating' G1 and 'quiescent' G0/G1 subpopulation, respectively), but the width of the shoulder of the radiation survival curve was reduced in the 'quiescent' subpopulation (Dq = 2.3 Gy vs. 5.3 Gy).

Influence of growth phase, nutrition and hypoxia on heterogeneity of cellular buoyant densities in in vitro tumor model systems

EMT6/Ro multicellular spheroids were sequentially dissociated into outer, middle and inner layers, and the buoyant densities of these subpopulations were compared to aerobic or exponential or plateau-phase monolayers by isopycnic density centrifugation using Percoll as the gradient medium. Spheroids were more heterogeneous in buoyant density distributions than monolayer cultures. The outer-layer cells of spheroids and fed plateau monolayers peaked at a similar density; the majority of middle-layer cells banded close to unfed plateau and exponential hypoxic monolayers, while most inner-layer cells banded where fed or unfed plateau hypoxic monolayer peaked in density. Our data suggest that metabolic heterogeneity due to growth phase, together with altered cellular microenvironment brought about by differences in oxygenation and external nutrient supplies between spheroids and monolayers, can be manifested in one biophysical parameter such as buoyant density.

Effect of N-acetylcysteine on the ciliary beat frequency of human bronchial explants

The effect of N-acetylcysteine on human bronchial cilia was evaluated by measuring the changes in ciliary beat frequency (CBF) on human bronchial explants exposed to 1%, 2%, 3%, 4%, and 5% concentrations of N-acetylcysteine solution in nutrient medium. There was a progressive reduction in CBF at increasing concentration, indicating an inhibitory effect on human ciliary activity in vitro (P less than 0.05).

Regrowth and radiation sensitivity of quiescent cells isolated from EMT6/Ro-fed plateau monolayers

A quiescent [denoted as Q(G0/G1)] subpopulation was isolated from EMT6/Ro-fed plateau monolayers by centrifugal elutriation. The median Coulter volume of these cells was significantly smaller than that of the original population from which they were elutriated. Using two-step acridine orange staining and dual parameter flow cytometric analysis, over 95% of quiescent cells were found to have G1 DNA content, and 80% of the cells had a decreased RNA content as compared to rapidly proliferating exponential G1 cells. After labeling for 24 hr (two doubling times) with [3H]thymidine, less than 2% of the quiescent cells incorporated [3H]thymidine as measured by autoradiography. The colony-forming efficiency of these cells was not significantly different from that of exponential cells. When such Q(G0/G1) cells were replated in fresh medium at a lower density, there was a lag time of 30 hr before any increase in cell number was detected, after which the cell-doubling rate matched that of exponential culture. Results obtained from the radiation dose-response curves showed that quiescent (G0/G1) cells were more radiosensitive than exponential G1 or unseparated fed plateau cells.

Ciliary beat frequency of human respiratory tract by different sampling techniques

The intrinsic ciliary beat frequency of human respiratory epithelium collected by 3 different biopsy techniques was examined. Ciliated epithelium was obtained by nasal brush, endobronchial brush, and endobronchial forceps biopsies from 15 patients during bronchoscopy, and ciliary beat frequency was determined in vitro at 37 degrees C using a photoelectric technique. The overall mean beat frequencies of nasal brush biopsy, endobronchial brush biopsy, and endobronchial forceps biopsy specimens were 14.3, 14.4, and 14.6 hertz, respectively. There were no significant differences (p greater than 0.05) in the overall means. Although for a given patient ciliary beat frequency was not significantly different between specimens obtained by the 3 different biopsy techniques, the pooled mean beat frequency varied from one subject to another (p less than 0.01).

Effect of pH, viscosity and ionic-strength changes on ciliary beating frequency of human bronchial explants

1. Ciliary activity is significantly influenced by chemical and physical properties of the liquid medium in which the cilia beat. 2. We studied the effect of changes in pH, ionic strength and viscosity on the ciliary beat frequency (CBF) of explants of human respiratory mucosa. 3. Optimal CBF was elicited at pH 7 . 0-9 . 0, with a marked reduction of CBF outside these limits. The CBF was well preserved at NaCl concentrations between 5 g/l (80 mmol/l) and 12 g/l (200 mmol/l), but there was rapid loss at concentrations below 0 . 5 g/l (10 mmol/l). The cilia beat best at viscosities below 1 . 0 centipoises (1 mN s m-2). Increase of the viscosity gradually decreases CBF with a significant drop at viscosities above 87 millipoises. 4. It is concluded that the above limits may fairly accurately indicate the actual physical characteristics of the periciliary environment ('sol layer') in vivo.

Ciliary inhibitory effects of asthma patients' sputum

1. Sputum sols, obtained from patients with chronic obstructive pulmonary diseases, were applied to frogs' isolated palates and the effect on ciliary beat frequency was examined. 2. During clinical exacerbations, a significant number of asthmatic patients produced a distinct, slurry type of sputum, which induced ciliostasis. This ciliary inhibition largely disappeared with clinical improvement, at which time there was also a change of the type of sputum from slurry to mucoid. 3. Samples obtained from normal volunteers and from the great majority of the patients, excluding those with asthma, had no effect on ciliary beating.

Sputum and ciliary inhibition in asthma

Twenty-eight sputum samples collected from 20 patients with chronic bronchial asthma of atopic and intrinsic clinical types were incubated with human bronchial explants to study their influence on ciliary motility. Of these, 19 (68%) of the sputa exerted a ciliary inhibitory effect of varying degree in a two-hour period. Analysis of the data indicates that (1) the ciliary inhibitory effect was invariably present when patients produced a distinctive slurry sputum; (2) this occurred more frequently during clinical exacerbations; (3) the induced ciliary inhibition was reversible on removal of the sputum; (4) the intensity of the ciliary inhibitory effect decreased with clinical improvement of the patient; (5) the inhibitory effect was unrelated to the medications used; (6) it was equally common in the atopic and the intrinsic types of asthmatic patients; (7) the effect was not pH dependent or related to the degree of eosinophilia. The ciliary inhibitory factor in sputum was identified as having a molecular weight of 6000-8000. It may play a part in the pathogenesis of asthma and recognition of sputum containing it carries implications for treatment.

Ciliary beat frequency in human respiratory explants

Ciliary beat frequency was measured in 60 human bronchial explants obtained by bronchoscopic biopsy. The average rate of beating, at 37 degrees C, was 12.8 +/- 1.3 beats/s, and this rate remained quite constant for periods as long as 4 h. This basic rate of ciliary beat did not seem to be affected by factors such as age, topographical source of the biopsy, underlying disease, smoking history, or chronic alcohol consumption. The values obtained probably represented the "intrinsic" or automatic beat pattern. It remains to be seen if this pattern might be subject to modulation in situ.