Systematic drug perturbations on cancer cells reveal diverse exit paths from proliferative state

During a cell state transition, cells travel along trajectories in a gene expression state space. This dynamical systems framework complements the traditional concept of molecular pathways that drive cell phenotype switching. To expose the structure that hinders cancer cells from exiting robust proliferative state, we assessed the perturbation capacity of a drug library and identified 16 non-cytotoxic compounds that stimulate MCF7 breast cancer cells to exit from proliferative state to differentiated state. The transcriptome trajectories triggered by these drugs diverged, then converged. Chemical structures and drug targets of these compounds overlapped minimally. However, a network analysis of targeted pathways identified a core signaling pathway - indicating common stress-response and down-regulation of STAT1 before differentiation. This multi-trajectory analysis explores the cells' state transition with a multitude of perturbations in combination with traditional pathway analysis, leading to an encompassing picture of the dynamics of a therapeutically desired cell-state switching.

The gas density measurement of one long distance supersonic molecular beam

The gas density of the supersonic molecular beam (SMB) is a crucial parameter for the fueling or diagnostic process in the tokamak experiments. Using the microphone, one improved method of gas density measurement is proposed, which can greatly improve the measurement capacity by about 3 orders of magnitude by studying the pulsed signal characteristic of the microphone when it is pushed by the SMB. The gas density of the SMB is measured within the axial range of 20-2000 mm, and the axial central density at 2000 mm is about 100 times less than that at 20 mm. It is also found that the radial density distribution follows the Gaussian function in both free expansion (where the SMB can expand freely without any influence from the vacuum chamber) and restricted expansion (where the expansion of the SMB is restricted inside the flight tube of the vacuum system). And the axial central density decreases with the axial distance, which follows the inverse square law in the free expansion, but it deviates from this law in the restricted expansion.

Cellular network entropy as the energy potential in Waddington's differentiation landscape

Differentiation is a key cellular process in normal tissue development that is significantly altered in cancer. Although molecular signatures characterising pluripotency and multipotency exist, there is, as yet, no single quantitative mark of a cellular sample's position in the global differentiation hierarchy. Here we adopt a systems view and consider the sample's network entropy, a measure of signaling pathway promiscuity, computable from a sample's genome-wide expression profile. We demonstrate that network entropy provides a quantitative, in-silico, readout of the average undifferentiated state of the profiled cells, recapitulating the known hierarchy of pluripotent, multipotent and differentiated cell types. Network entropy further exhibits dynamic changes in time course differentiation data, and in line with a sample's differentiation stage. In disease, network entropy predicts a higher level of cellular plasticity in cancer stem cell populations compared to ordinary cancer cells. Importantly, network entropy also allows identification of key differentiation pathways. Our results are consistent with the view that pluripotency is a statistical property defined at the cellular population level, correlating with intra-sample heterogeneity, and driven by the degree of signaling promiscuity in cells. In summary, network entropy provides a quantitative measure of a cell's undifferentiated state, defining its elevation in Waddington's landscape.

Stability and chaotification of vibration isolation floating raft systems with time-delayed feedback control

This paper presents a systematic study on the stability of a two-dimensional vibration isolation floating raft system with a time-delayed feedback control. Based on the generalized Sturm criterion, the critical control gain for the delay-independent stability region and critical time delays for the stability switches are derived. The critical conditions can provide a theoretical guidance of chaotification design for line spectra reduction. Numerical simulations verify the correctness of the approach. Bifurcation analyses reveal that chaotification is more likely to occur in unstable region defined by these critical conditions, and the stiffness of the floating raft and mass ratio are the sensitive parameters to reduce critical control gain.

Dynamic changes in blood solubility of desflurane, isoflurane, and halothane during cardiac surgery

OBJECTIVE

To determine an estimate of blood/gas partition coefficients of volatile anesthetics during cardiac surgery.

DESIGN

Descriptive

SETTING

University hospital

PARTICIPANTS

Six adult patients undergoing valvular replacement with hypothermic cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

Blood samples were obtained from patients at 6 time points: before induction, at skin incision, at aortic cannulation, at rewarming during bypass, at weaning off bypass, and at skin suture. Measured blood/gas partition coefficients were plotted against corresponding solubilities estimated according to the combined effects of hypothermia and hemodilution. Significant differences were found in blood/gas partition coefficients of the 3 anesthetics at different times during surgery (p < 0.05). Blood/gas partition coefficients at weaning off bypass were the lowest, about 75% of that before anesthetic induction. A direct linear relationship for estimated solubility against measured solubility was found (r2 = 0.94; p < 0.05).

CONCLUSION

Dynamic changes in blood/gas partition coefficients of volatile anesthetics were found during cardiac surgery. They could be estimated by using multiple linear regression equations reflecting the combined effects of hypothermia and hemodilution.

Blood solubilities of volatile anesthetics in cardiac patients

OBJECTIVE

To determine and compare the effects of hematocrit and serum constituents on the blood solubilities of volatile anesthetics in different cardiac surgical patients.

DESIGN

Descriptive

SETTING

University hospital.

PARTICIPANTS

Twenty healthy adult volunteers, 40 adult cardiac patients, and 20 pediatric cardiac patients.

MEASUREMENTS AND MAIN RESULTS

Blood/gas partition coefficients of desflurane, isoflurane, and halothane; hematocrit; and serum concentrations of cholesterol, triglyceride, albumin, and globulin were determined in healthy adult volunteers, adult patients with coronary artery disease or rheumatic heart disease, and pediatric patients with cyanotic or acyanotic congenital heart disease. Statistical analysis was used to determine the difference in serum constituents and blood solubility of each anesthetic among volunteers and patients with different cardiac diseases. Triglyceride and blood/gas partition coefficients of the 3 volatile anesthetics in the patients with coronary artery disease were significantly higher than those in healthy volunteers and the patients with rheumatic heart disease (p < 0.05). Hematocrits were significantly higher in cyanotic children than acyanotic children (p < 0.05), but the serum constituents and anesthetic solubilities were not different between the 2 groups (p > 0.05).

CONCLUSION

Patients with coronary artery disease have significantly higher serum triglyceride and blood/gas partition coefficients for desflurane, isoflurane, and halothane than healthy volunteers and patients with rheumatic heart disease. Although cyanotic children have higher hematocrits compared with acyanotic children, no significant difference in anesthetic blood gas solubilities was found between the 2 groups.

The effect of temperature on solubility of volatile anesthetics in human tissues

Hypothermia often occurs during surgery, a factor influencing anesthetic pharmacokinetics through its influence on solubility. Information on the tissue solubility of volatile anesthetics under hypothermia is limited. The present study supplies this information for the solubility of volatile anesthetics in human tissues. Tissue specimens of brain, heart, liver, muscle, and fat were obtained from 10 postmortem males (27 +/- 8 yr). Tissue/gas partition coefficients of desflurane, sevoflurane, enflurane, isoflurane and halothane were measured at 37 degrees C, 33 degrees C, 29 degrees C, 25 degrees C, 21 degrees C, and 17 degrees C. For each given tissue, the order of tissue/gas partition coefficient was halothane >enflurane >isoflurane >sevoflurane >desflurane. Tissue/gas partition coefficients at 37 degrees C differed significantly (P < 0.05) across drugs, except that liver/gas partition coefficients for isoflurane and enflurane did not differ. The logarithm of all tissue/gas partition coefficients increased linearly with decreasing temperature (P < 0.05). In conclusion, hypothermia increases tissue/gas partition coefficients of volatile anesthetics. The increases are proportional to those for blood/gas partition coefficients, and therefore tissue/blood partition coefficients will not change during hypothermic conditions.

IMPLICATIONS

Volatile anesthetics are often used during hypothermic conditions, and tissue solubility of volatile anesthetics is an important determinant for the wash-in and washout of the anesthetics in tissue. Tissue/gas partition coefficients during hypothermia have implications for understanding the pharmacokinetics of volatile anesthetics at hypothermic conditions.

Mechanisms of G1 checkpoint loss in resected early stage non-small cell lung cancer

Loss of the G1 checkpoint appears to be extremely common among virtually all neoplasms. A variety of genetic and epigenetic mechanisms have been demonstrated to play significant roles in this process. In a consecutive series of early stage non-small cell lung cancer (NSCLC), we have established the loss of expression of the G1 Cdk inhibitors p15INK4b) and p16INK4a by DNA methylation is very common (37%), and methylation of p16INK4a is tightly correlated with loss of expression of p16INK4a protein (P = 0.0018). Furthermore, methylation of p15INK4b and p16INK4a appear inversely correlated, although methylation of p15INK4b is an infrequent event in this cohort (4%). Methylation was detected in all stages of NSCLC equally, and did not correlate with survival in these patients. Evidence for methylation was more frequent in squamous cell carcinomas in comparison to other tumor histologies (P = 0.0156). In addition, over-expression of cyclin D1 was found to be tightly restricted (P = 0.0032) to those tumors that had retained wild-type expression of pRB, and did not correlate with methylation or expression of p16INK4a gene product. Although loss of p16INK4a function remains tightly correlated with pRB expression, loss of other regulatory elements in NSCLC such as p53 mutation and cyclin D1 over-expression appear independent of loss of the p16INK4a gene product.

Prediction of volatile anaesthetic solubility in blood and priming fluids for extracorporeal circulation

Volatile anaesthetics are often used during cardiopulmonary bypass (CPB). To understand the kinetics of inhaled anaesthetics during CPB, anaesthetists should understand changes in blood solubility caused by fluid use. We set out to predict the solubility of three volatile anaesthetics, desflurane, isoflurane and halothane, during CPB by determining: (i) their solubility in fresh whole blood and eight CPB priming fluids at 37 degrees C; (ii) the effect of temperature on the solubility of these anaesthetics in lactated Ringer's, gelofusin, banked blood and plasma; (iii) their solubility in different mixtures of these four priming fluids at different temperatures; and (iv) their estimated and actual solubility in blood during hypothermic CPB. We calculated solubility using a concept of volume fraction partition coefficient and compared estimated and measured solubilities. For the three anaesthetics tested, solubilities are in the order: fresh whole blood approximately = plasma > banked blood > normal saline approximately = lactated Ringer's approximately = gelofusin approximately = Haemaccel approximately = hydroxyethyl starch > mannitol. The solubilities of the anaesthetics in all priming fluids increased logarithmically at lower temperatures (P<0.05). The volume-fraction estimates of the partition coefficients were within approximately +/-20% of the measured values for all values of solubility. The corresponding estimates of solubility for CPB blood samples were between -36% and +24% of the measured values. During normothermic CPB, blood solubility of volatile anaesthetics would be unchanged when using plasma, slightly reduced when using banked blood and markedly reduced when using crystalloids and colloids.

Gene therapy of established mesothelioma xenografts with recombinant p16INK4a adenovirus

The absence of expression of the p16INK4a gene product is observed in virtually all mesothelioma tumors and cell lines, whereas wild-type pRB expression is maintained. We have examined the potential therapeutic role of re-expressing the p16INK4a gene product in mice with established human mesothelioma xenografts. Experiments using Adp16 treatments in mesothelioma xenografts demonstrated prolonged survival and potential cure following treatment with p16INK4a-based gene therapy. These results demonstrate that p16INK4a gene transfer may play a therapeutic role in the treatment of mesothelioma.

[A preliminary study of developmental genetics of polymorphic serum esterase in domestic fowls]

Polymorphism of serum esterase was examined in 3 Super-Y 2000 broiler breeding populations differing in developmental stages (i.e. day 120, 180 and 300) using vertical polyacrylamide gel electrophoresis. The results indicated that both Es-1 and Es-2 loci exhibited polymorphism. Two to three polymorphic enzyme bands were detected at zone Es-1, and one band at zone Es-2 after electrophoresis. It was first discovered in this work that obvious developmental difference in products of Es-1 alleles existed with female birds, polymorphic bands of which disappeared after onset of lay. An individual tracing experiment conducted in a Super-Y 380 commercial layer population and an extensive experiment carried out in 2 ISA B380 parent CD stocks supported the previous finding. It could thus be inferred that phenotype "O" (no band at Es-1) discovered in hens was not genetically controlled by the recessive allele Es-1(0), which itself did not exist, but might be an evidence of gene regulation at laying period. For female birds, expression of Es-1 alleles was active before sexual maturity, and depressed after onset of lay, to meet their physiological need of high level of blood esterase for laying. It could also be inferred that this developmental difference in serum esterase polymorphism might be a common phenomenon in all avian species. If this hypothesis were true, the synthesis of esterase inside avian bodies could be a desirable model for investigating expression, and regulation of expression, of genes in avian populations.

Electrochemical generation of ferrylmyoglobin during oxidation of styrene with films of DNA and a poly (ester sulfonic acid) ionomer

The chemistry of electrochemically-driven myoglobin-catalyzed oxidation of styrene was investigated in films of DNA or Eastman AQ ionomer on optically transparent electrodes. Conversion of styrene to styrene oxide proceeded via a ferrylmyoglobin radical intermediate. Ferrylmyoglobins were clearly detected by spectroelectrochemistry in films of 1-4 mm thick. The ferrylmyoglobin radical is produced by reaction of metmyoglobin (Mb) in the films with hydrogen peroxide formed by electrochemical catalytic reduction of oxygen catalyzed by Mb. Thus, electrochemically-driven styrene oxidation with these films proceeds by a 'doubly catalytic' electrode-driven reduction-oxidation pathway. Ferrylmyoglobin formation during electrolysis of Mb-DNA films in aerobic solutions was much faster, and styrene oxidation occurred with less Mb decomposition compared to the Mb-AQ films. The better performance of Mb-DNA films is correlated with a larger fraction of electroactive Mb and better stability than for the Mb-AQ films.

Equilibrium intermediates in the unfolding pathway of creatine kinase

The unfolding of creatine kinase in various concentrations of guanidine hydrochloride of increasing concentrations has been investigated by combination of size-exclusion chromatography (SEC) with other methods. There are two peaks in the profiles of SEC in GuHCl at moderate concentrations, showing that unfolding of creatine kinase goes through dimeric and monomeric intermediates with increasing guanidine hydrochloride concentrations. Both intermediates have relatively compact structure and retain considerable ordered structure.

Histone acetyltransferase activity and interaction with ADA2 are critical for GCN5 function in vivo

Yeast GCN5 is one component of a putative adaptor complex that includes ADA2 and ADA3 and functionally connects DNA-bound transcriptional activators with general transcription factors. GCN5 possesses histone acetyltransferase (HAT) activity, conceptually linking transcriptional activation with enzymatic modification at chromatin. We have identified the minimal catalytic domain within GCN5 necessary to confer HAT activity and have shown that in vivo activity of GCN5 requires this domain. However, complementation of growth and transcriptional activation in gcn5- cells required not only the HAT domain of GCN5, but also interaction with ADA2. The bromodomain in GCN5 was dispensable for HAT activity and for transcriptional activation by strong activators; however, it was required for full complementation in other assays. Fusion of GCN5 to the bacterial lexA DNA binding domain activated transcription in vivo, and required both the HAT domain and the ADA2 interaction domain. These results suggest that both functions of GCN5, HAT activity and interaction with ADA2, are necessary for targeting and acetylation of nucleosomal histones.

Characterization of a tunable optical parametric oscillator laser system for multielement flame laser excited atomic fluorescence spectrometry of cobalt, copper, lead, manganese, and thallium in buffalo river sediment

A pulsed (10 Hz) optical parametric oscillator (OPO) laser system based on beta-barium borate (BBO) crystals and equipped with a frequency-doubling option (FDO) was characterized for use in laser excited atomic fluorescence spectrometry (LEAFS). This all-solid-state laser has a narrow spectral line width, a wide spectral tuning range (220-2200 nm), and a rapid, computer-controlled slew scan of wavelength (0.250 nm s-1 in the visible and infrared, and 0.125 nm s-1 in the ultraviolet). The output power characteristics (15-90 mJ/pulse in the visible, 1-40 mJ in the infrared, and 1-11 mJ in the ultraviolet), laser pulse-to-pulse variability (3-13% relative standard deviation, RSD, of the laser pulses), conversion efficiency of the FDO (2-17%), and spectral bandwidth in the visible spectrum (0.1-0.3 cm-1) were measured. The laser was used as the excitation source for a flame LEAFS instrument for which rapid, sequential, multielement analysis was demonstrated by slew scan of the laser. The instrument allowed about 640 measurements to be made in about 6 h, with triplicate measurements of all solutions and aqueous calibration curves, which yielded accurate analyses of a river sediment (National Institute of Standards and Technology, Buffalo River Sediment, 2704) for five elements with precisions < 5% RSD. Comparable or improved flame LEAFS detection limits over literature values were obtained for cobalt (2 ng mL-1), copper (2 ng mL-1), lead (0.4 ng mL-1), manganese (0.2 ng mL-1), and thallium (0.9 ng mL-1) by flame LEAFS.

VH and VL gene analysis in sporadic Burkitt's lymphoma shows somatic hypermutation, intraclonal heterogeneity, and a role for antigen selection

Tumor cell lines and one tumor biopsy from seven cases of Epstein-Barr virus (EBV) genome-negative sporadic Burkitt's lymphoma (BL) have been investigated for usage and mutational pattern of Ig variable region genes. The VH genes were derived from the VH 3 (one) and VH4 (six) families and both the IgM-positive (six) and the IgA-positive (one) were all mutated from their germline counterparts. The VL genes were derived from V kappa 1 (one), V kappa 3 (one), V lambda 1 (four), and V lambda 2 (one) families and were also somatically hypermutated. Biopsy material from one of the IgM-positive cases showed VH and VL sequences that matched the derived cell line, with additional intraclonal sequence heterogeneity, indicating that the tumor cells had undergone posttranformation somatic mutation. Mutational patterns in V(H) genes did not show a conventional role for antigen in selecting tumor cell sequences. In contrast, patterns in VL sequences were consistent with a role for antigen in five of seven cases. The pattern of extensive scattered somatic hypermutation and intraclonal variation is similar to that in VH sequences of EBV genome-positive endemic BL, although the degree of mutational activity is less. These common features indicate that B cells involved in the two variants of BL may share a common clonal history.

Creatine kinase: the characteristics of the enzyme regenerated from the thio-methylated creatine kinase reflect a differentiation in function between the two reactive thiols

The activity of S-thiomethyl-modified creatine kinase is due to regeneration of the free thiol (Hou and Vollmer, Biochim Biophys Acta (1994) 1205, 83-88). Characteristics of enzyme regenerated from the S-thiomethyl-modified creatine kinase are reported in the present study. The intrinsic fluorescence of the regenerated enzyme is similar to that of the native enzyme in the presence or absence of the dead-end complex. Regenerated CK (rCK) with full activity has only one reactive thiol. The rate constant of the rCK-reactive thiol reacting with DTNB is close to that of the slow phase of the reactive thiols of the native enzyme. If the IAM-modified rCK is treated with the same method as that for obtaining the rCK, the thiol-methylated reactive thiol of the rCK is reduced to a free SH and a regenerated enzyme, RCK, is produced with about 10% of the rCK activity. Therefore, the different roles of the two reactive thiols of creatine kinase may stem from the characteristics of the rCK, which suggests that only one of the two reactive thiols is related to the activity of the enzyme and the slower phase thiol (the first SH) in the modification reaction with DTNB is directly related to the enzymatic activity, while the faster phase thiol (the second SH) assists the first SH. This compensatory mechanism is proposed in the present study to interpret the dispute on the reactive SH role in the enzymatic catalysis.

Isolation and some properties of glycated D-glyceraldehyde-3-phosphate dehydrogenase from rabbit muscle

Glycated D-glyceraldehyde-3-phosphate dehydrogenases (GAPDH) from rabbit muscle and human erythrocytes have been investigated. The specific activity of the non-glycated GAPDH from rabbit muscle is approx. 180 units. (One unit is defined as the specific activity required to convert 1 microM of substrate/min per mg of enzyme.) The activity of the glycated enzyme, consisting of two sugars per tetramer, is lower than that of the non-glycated GAPDH. Non-enzymic transamination of the N-termini of glycated GAPDH (gGAPDH) indicates that they are not blocked by glycation. The rate of modification of thiols (Cys-149) with 5,5'-dithiobis-(2-nitrobenzoic acid) was greater for the glycated than the non-glycated enzymes. The rate of modification of amino groups of Lys residues of gGAPDH with o-phthalaldehyde was greater for the non-glycated enzyme. In 0.18 M guanidine-HC1 solution, the emission intensity at 410 nm of a fluorescent NAD+ derivative introduced into the active site decreased to 80%, whereas that of gGAPDH decreased to 50%. This suggests that the glycated sites are near the active site; glycation of the enzyme leads to a change of the microenvironment of Cys-149, alters the conformation of the active site and decreases the activity.

[Experimental study on kidney invigorating and lipid reducing decoction-yishen jiangzhi tang in the treatment of chronic renal failure]

In exploring the effect of treatment of supporting the body resistance on chronic renal failure, a chronic renal failure model of rat was created by gastroperfusion of adenine and evaluation was made on the therapeutic effect of Kidney Invigorating and Lipid Reducing Decoction (KILRD). The mental state and body weight of the treated group have recovered well with polyuria and proteinurea improving, BUN and Creatinine decreasing, which appeared to be superior to the naturally recovered group. Renal pathological examination showed that: although the renal parenchymal damage was not reversed but its compensation was satisfactory with compensatory hypertrophy appearing in unaffected nephron. The dominant reaction in the affected area was polynucleomacrocytosis, foreign body granulamatosis, and interstitial lymphocytic infiltration, the fibrosis was inevident, while the above-mentioned condition in the naturally recovered group was relatively more serious, with fibrosis being observed. It was indicated that KILRD could increase the compensatory capacity and immunity, promote protein synthetization and improve renal function. The study on KILRD proved to be a significant conservative medical treatment for chronic renal failure.

Mass spectrometry software for biochemical analysis in electrospray and fast atom bombardment modes

New mass spectrometry techniques, such as electrospray ionization (ESI), allow the study of large biomolecules and peptide mixtures. The data produced are complex and interpretation can be a long and tedious process. A new suite of data-processing software is described which allows many of these operations to be carried out in a rapid, automated way. Software is described for the deconvolution of the spectra of multiply charged ions, for both pure compounds and mixtures. The rapid peptide mapping of protein digests from h.p.l.c.-m.s. data and peptide sequence confirmation from multiple-stage (MS)-m.s. data using tandem quadrupole m.s. are also described. In addition preliminary results are presented on first principle sequencing of unknown peptides from MS-m.s. experiments.

[Clinical and CT analysis of 35 cases of lumbar disc herniation before and after non-operative treatment]

35 cases of lumbar disc herniation were examined by clinical diagnosis and CT scanning. The results showed that there were 36 disc herniation (1 case of dual disc herniation). The radius vector of disc was 6.3 mm and the transverse diameter was 18.6 mm. There were 30 cases with sac of dura mater of spinal cord or nerve roots pressed and adhesive, yellow ligaments pachismus, lateral recessus filling and narrow bony lumbar vertebral canal. All patients were treated by means of manipulation. The clinical results showed that 29 cases (82.8%) had superior effects and 33 cases were effective. The clinical effective rate was 94.2%. CT re-scanning showed that disc reposition completely returned was 6 cases, and partially returned was 24 cases. The successful rate of the reposition by manipulation was 83.3%. The clinical analysis and CT showed that herniation of lumbar disc could be repositioned by means of manipulation. The reposition of herniation of disc was a key factor in clinical results but was by no means the only one. With regard to long duration of illness, repeated invasion, combined narrow bony lumbar vertebral canal, and non-improved central type herniation after a long period of treatment, the herniation of disc should be treated by operation.

[Influence of laurocapram on ultrastructures of mouse skin and sarcoma 180 membrane]

Laurocapram (Lau), 1-dodecyl-hexahydro-2 H-azepin-2-one, (azone) is a new percutaneous penetration enhancer. However, the mechanism of its action for absorption promoter of other agents is still unknown. In this paper the effect of Lau on ultrastructures of skin surface and tumor cell membrane were studies. Lau (2%) suspension was applied to abdominal skin of ICR/JCL, C 57 BL mice or one side of abdominal skin of nude mouse with drug and other side with the vehicle solvent once daily for 2-3 d. The skin was excised at 4 h after the final medication for examination under scanning electron microscope (SEM). The results showed the numerous small infolding lines which divided the skin surface into small areas with vesiculation and peeled the epidermal surface to form a few minor holes. The cuticles of the hair shaft dropped off and became thinner. Numerous desquamated cells around the orifice of the hair were fractured, detached and widened. Sarcoma 180 cells were incubated with Lau 25 micrograms/ml at 37 degrees C for 4 h. The microvilli of some cells dropped off and the size of villi became thinner and shorter. The top of some villi of the cells appeared occasionally thick to make the profile as a bat. The surface of numerous naked cells became rugged and rough and showed many black minor holes in the area of denuded cell membrane or dropped microvilli. More than 100 holes in the exposed surface of the naked cell were seen. It seemed that the Lau drilled holes on the biomembrane and enlarged the orifice of hair follicles and thus enhanced the transdermal absorption.