Biomedical subjects

C F Chang

Publications and source records attributed to C F Chang.

At least 109 records · Page 6Linked to original sources

PubMed1995

Clinical significance of intratumoral blood flow in cervical carcinoma assessed by color Doppler ultrasound.

BACKGROUND: Much evidence has suggested that vascular density reflects the clinical behavior of cancer. In this study, the intratumoral blood flow in cervical carcinomas was assessed by transvaginal color Doppler ultrasound, and its clinical significance was evaluated. METHODS: Sixty-five patients with Stage Ib-IIb cervical carcinoma exhibiting visible cervical tumor by transvaginal ultrasound were enrolled. All patients were scheduled for radical hysterectomy and pelvic lymph node dissection. Transvaginal color Doppler ultrasound was performed before surgery to search for blood flow signals from the tumor and the main uterine artery. The corresponding arterial resistance index (RI) was calculated. Clinical and pathologic data were recorded. A cytokinetic study was performed by propidium iodide staining and flow cytometry. The human papillomavirus (HPV) status was assessed by polymerase chain reaction. RESULTS: Intratumoral blood flow was detected by color Doppler ultrasound in 46.2% (30/65) of the tumors. Patients with detectable intratumoral blood flow exhibited significantly more pelvic lymph node metastasis (10/30 vs. 2/35, P = 0.005), a higher percentage of cancer cells in the S- + G2M-phase (30.02 +/- 18.54% vs. 19.35 +/- 11.21%, P < 0.005), and a higher prevalence of HPV infection (30/30 vs. 25/35, P = 0.001) when compared with those without intratumoral blood flow. No significant difference was observed concerning the patient's age, tumor size, clinical staging, histologic type, and DNA ploidy status between these two groups. Regression analysis of the intratumoral RI value on the S- + G2M-phase fraction showed linear regression (n = 30, r2 = 0.501, P < 0.01). The RI values of the main uterine artery showed no significant difference between these two groups. CONCLUSION: The intratumoral blood flow by transvaginal color Doppler ultrasound correlated well with a higher proliferation index, higher incidence of HPV infection, and pelvic lymph node metastasis in cervical carcinoma.

Adult↗

PubMed1995

Cooperative action of cellular proteins YB-1 and Pur alpha with the tumor antigen of the human JC polyomavirus determines their interaction with the viral lytic control element.

Human JC polyomavirus (JCV) is the etiologic agent of the neurodegenerative disease progressive mulifocal leukoencephalopathy. By using JCV as a model, we investigated the role of the viral early protein tumor antigen (TAg) in the binding of two cellular proteins, Pura alpha and YB-1, to JCV regulatory sequences. Results from band-shift assays with purified YB-1, Pur alpha, and TAg indicated that efficient binding of Pur alpha, a strong activator of early gene transcription, to a single-stranded target sequence corresponding to the viral lytic control element, is diminished in the presence of the late gene activator YB-1, which recognizes the opposite strand of the Pur alpha binding site. Of particular interest was the ability of Pur alpha and TAg to enhance binding of YB-1 to DNA molecules without being associated with this complex. Binding studies using a mutant peptide encompassing the N terminus of YB-1 indicated that the C terminus of YB-1 is important for its DNA binding activity. The ability of Pur alpha and TAg to increase binding of YB-1 to DNA is independent of the YB-1 C terminus. Similarly, results from band-shift assays using Pur alpha variants indicated that two distinct regions of this protein contribute either to its ability to bind DNA or to its ability to enhance YB-1 DNA binding activity. Based on the interaction of Pur alpha, YB-1, and TAg, and their binding to DNA, a model is proposed for the role of these proteins in transcription of viral early and late genes during the lytic cycle.

Animals↗

PubMed1995

Stimulation of spermatogenesis or of sex reversal according to the dose of exogenous estradiol-17 beta in juvenile males of protandrous black porgy, Acanthopagrus schlegeli.

The objective was to investigate the effects of various doses of estradiol-17 beta (E2) on gonadal development, gametogenesis, and plasma levels of sex steroids in 1-year-old protandrous male black porgy, Acanthopagrus schlegeli. Juvenile black porgy were divided into four groups, fed with control diet or diet mixed with E2 (0.25, 1.0, or 4.0 mg/kg feed) for 7 months, respectively. Significantly higher gonadosomatic index was observed in the 0.25- and 1.0-mg E2 groups compared to that in the control and 4.0-mg E2 groups during the spawning season. E2 at 4.0 mg completely suppressed spermiation, while lower doses of E2 (0.25 and 1.0 mg) delayed spermatogenesis but increased the number of spermiating fish and spermiation volume. Sperm concentrations were similar in spermiating black porgy. At 10 months and older, gonads in all the groups except E2 (4.0-mg)-treated fish underwent an intensive spermatogenesis while spermatids were not observed until 11 and 12 months in the 0.25- and 1.0-mg E2 groups, respectively. Primary oocytes appeared in the 10- and 11-month-old gonads in testicular tissue of the 1.0- and 4.0-mg E2 groups. After 5 months of 4-mg E2 treatment, testicular tissue regressed and ovarian tissue with primary oocytes developed. Elevated levels of plasma E2 were observed only in the 4.0-mg E2 group while low levels of E2 and testosterone (T) were observed in the control and other E2-treated groups. Significantly higher levels of plasma 11-ketotestosterone (11-KT) were observed in the 0.25- and 1.0-mg E2-treated groups during the spawning season. Plasma vitellogenin levels showed a dose-dependent effect of E2 treatment. The present data suggest that exogenous E2 could stimulate the development of either testicular or ovarian tissues, depending on the dosage of E2. Plasma 11-KT but not T concentrations closely correlate with testicular development and spermiation in black porgy.

Animals↗

PubMed1995

Immersion in bovine insulin stimulates growth of tilapia.

The objective of this study was to investigate the effects of bovine insulin on growth responses in tilapia. Juvenile hybrid male tilapia (Oreochromis niloticus x O aurea; n = 135) were subjected to 1 of 3 treatments. Each treatment was subdivided into 3 replicates of 15 fish each. The fish were immersed into 1 of 2 doses (10 and 100 micrograms/100 ml water) of insulin or no hormone for 15 min per week for 8 weeks. Body weight, growth and feed conversion efficiency were significantly higher as a result of the first 4 weeks of insulin treatment as compared to control fish. The lower dose of insulin had a better stimulation effect than that of the higher doses. Insulin also stimulated feed consumption. Liver protein and protein/DNA ratio were higher in both insulin-treated groups than in the control group. Muscle proximate composition and hepatosomatic index were similar in the insulin-treated and control groups. The experimental findings suggest that insulin administered by immersion can enhance growth, feed consumption, food utilization and liver cell size in tilapia.

Animal Nutritional Physiological Phenomena↗

PubMed1995

A microencapsulated analog of LH-RH accelerates maturation but without stimulating sex reversal in the protandrous black porgy, Acanthopagrus schlegeli.

The objective of this study was to regulate the reproduction and levels of gonadal steroids in 3-year-old protandrous black porgy (Acanthopagrus schlegeli) by treatment with microencapsulated D-Trp6-luteinizing hormone-releasing hormone (LH-RH analog) during the prespawning season. Twenty-four previously male black porgy were equally divided into 2 groups and injected with vehicle (control group) or with microencapsulated LH-RH analog (LH-RH analog group), respectively. Spermiation and plasma levels of testosterone (T), estradiol-17 beta (E2) and 17 alpha-hydroxyprogesterone (17 alpha-OH P) were measured, after treatment, at intervals of 1-2 weeks for 4 months. Oocyte diameters were also measured after 4, 10, 12, 14 and 16 weeks of treatment. The microencapsulated LH-RH analog accelerated the onset of spermiation by at least 5 weeks. Oocyte diameters were also significantly increased in the LH-RH analog group. The microencapsulated LH-RH analog did not increase the number of sex-reversing females compared with the number in the control group. High levels of plasma E2 were found in the sex-reversing females in the LH-RH analog and control groups during the prespawning and spawning season. Low levels of plasma E2 were observed in the non-reversed males in both the LH-RH analog and the control groups. Similar profiles of plasma T levels were detected in male and in reversing female black porgy in the LH-RH analog and control groups. Plasma 17 alpha-CH P levels were low and constant throughout the experimental period in fish in each group. These findings indicate that the microencapsulated LH-RH analog accelerated gonadal maturation in the black porgy during the prespawning season. Plasma levels of E2 seem to be closely related to the occurrence of natural sex reversal in the protandrous black porgy, A schlegeli.

17-alpha-Hydroxyprogesterone↗

PubMed1995

Isolation and characterization of a type II JC virus from a brain biopsy of a patient with PML.

Brain tissue of a patient with multiple myeloma suffering from neurological disorders similar to those seen in progressive multifocal leukoencephalopathy (PML) patients was evaluated for the presence of the papovavirus, JCV. Results from polymerase chain reaction (PCR) revealed the presence of JCV with structural organization at the control region which is distinct from well-characterized isolates, ie Mad-1 and Mad-4. The control region of the new isolate, named JCVPhila-1' contains a 22 nucleotide insertion which separates the TATA box from the NF-1 regulatory motif. Only 18 nucleotides of the insert are duplicated in the second copy of the enhancer/promoter of the new isolate, which is 84 nucleotides in size. Results from a transcription assay indicate a modest elevated level of JCVPhila-1 early promoter activity compared to that of JCVMad-4 in glial cell lines. The basal and T-antigen-induced transcriptional activities of the JCVPhila-1 late promoter was lower with respect to Mad-4 late gene activity in glial cells. Of particular interest was the observation that in the cells producing the early protein, T-antigen, JCVPhila-1 DNA replicated more efficiently then the Mad-4 DNA. These results suggest that the alterations seen in the JCVPhila-1 control region may differentially influence early and late gene expression and facilitate amplification of the viral genome in cells derived from the CNS.

Aged↗

PubMed1995

Factors influencing the success rates of endoscopic nasobiliary drainage in treatment of obstructive jaundice.

BACKGROUND: Endoscopic nasobiliary drainage (ENBD) is a safe and effective modality which has been well documented for obstructive jaundice. However, factors predicting success rate of ENBD remain inconclusively. This study analyses those factors and discusses the outcome of patients with obstructive jaundice. METHODS: One hundred and sixteen patients (male 99, female 17; mean age 68.2 years) with obstructive jaundice received ENBD after endoscopic retrograde cholangiogram (ERC) by Olympus JF-lT20 endoscope and 7F Wilson-Cook nasobiliary catheter from Sep. 1990 to Oct. 1993. Bile output (QD), serum bilirubin (BIW), liver biochemistry (QW), bile culture (next day), blood culture (if BT > 38.5 degrees C) were checked until definite treatment or death. Adequate drainage was defined as a daily output of bile more than 200cc, a gradual drop in serum bilirubin and no signs of cholangitis. Factors such as causes of jaundice, obstruction level, serum bilirubin, albumin, juxtapapillary diverticulum (JPD), bacteremia, fever before ERCP and ascites were analyzed. RESULTS: The success rate was 86.2% (100/116) in ERC and 78% (78/100) in ENBD. Adequate biliary drainage was 82.1% (64/78), and serum bilirubin was reduced from 14.3 +/- 8.5 mg% to 7.5 +/- 5.6 mg% within one week. In patients with non-cancerous causes, higher success rate and adequate drainage rate were obtained compared with those with cancerous causes (94.3% vs. 69.2%, p < 0.01 and 88.6% vs. 50.8%, p < 0.01, respectively). In all patients, a higher success rate was achieved at the obstruction level at the common bile duct (CBD) compared with periampullary and hilar levels (90.7% vs 69.2%, p < 0.05 and 90.7% vs 28.6%, p < 0.001, respectively). In patients with cancer as a cause, higher success rate was achieved at CBD level than at hilar level (85% vs 28.6%, p < 0.05). Those patients with cancer and serum bilirubin above 15 mg/dl had a higher failure rate in ENBD. Success rate of ENBD was not related to the presence of JPD, bacteremia or fever before ERCP and serum albumin level. CONCLUSIONS: Factors decreasing the success rates of ENBD were underlying cancerous causes, obstruction level at hilum or periampullary region and serum bilirubin level more than 15 mg%.

Adult↗

PubMed1995

A prospective, randomized trial of sclerotherapy versus ligation in the management of bleeding esophageal varices.

We conducted a prospective, randomized trial comparing sclerotherapy and ligation in 120 patients with acute bleeding of esophageal varices. All the patients were cirrhotic, 59 received sclerotherapy, and 61 received ligation. Treatment was repeated regularly until the varices were obliterated. The mean follow-up period was 295 +/- 120 days and 310 +/- 105 days for the sclerotherapy and ligation groups, respectively. The control of active bleeding was 12/15 (80%) in the sclerotherapy group and 18/19 (94%) in the ligation group (P = .23). The numbers of treatment sessions required to achieve variceal obliteration were 6.5 +/- 1.2 in the sclerotherapy group and 3.8 +/- 0.4 in the ligation group (P < .001). Recurrent bleeding from the gastrointestinal tract was 51% in the sclerotherapy group compared with 33% in the ligation group (P < .05). Recurrent bleeding from esophageal varices was 36% in the sclerotherapy group and 11% in the ligation group (P < .01). However, bleeding from ectopic varices and congestive gastropathy was less common in the sclerotherapy group (7%) than in the ligation group (18%) (P = .05). Significant complications were encountered in 19% of the sclerotherapy group and in 3.3% of the ligation group (P < .01). Comparison of Kaplan-Meier estimates of time to death of both groups showed a significantly lower mortality in the ligation group (P = .011). Both sclerotherapy and ligation can effectively arrest active bleeding from esophageal varices. However, ligation is more effective than sclerotherapy in decreasing the risk of rebleeding from esophageal varices with fewer complications. Ligation can also achieve obliteration of esophageal varices more rapidly than sclerotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Dead on arrival study in Kaohsiung area.

Dead on arrival (DOA) is a distressful situation for most medical personnel and families. There are few papers about this topic in Taiwan though most DOAs are unexpected and sudden with or without underlying disease as predisposing factors. From January 1, 1993 to December 31, 1993, 487 DOA patients were sent to 4 large hospitals in the Kaohsiung area (including Kaohsiung City and Kaohsiung County). A retrospective study was carried out through questionnaires. The incidence was 0.22%, the male to female ratio was 2.25, and the largest age group was 61 to 75 years old. Most patients were sent to nearby hospitals and sent by non-medical personnel with non-ambulance motor vehicles. It is hard to define the exact time from arrest to arrival at the hospital, but the initial cardiac rhythm was mostly asystole. Only 1.44% of DOA patients survived and only 9.24% responded to resuscitation. About 31.42% of patients had no evident cause of death, 40.04% non-trauma deaths, and 28.54% trauma deaths. Most of the underlying diseases were treated regularly by medical specialists if past history could be traced. Though our emergency medical service system (EMSS) has been active since 1990, there are still several drawbacks. Public education of cardiopulmonary resuscitation, easy access to EMSS, and appropriate management in hospitals must be stressed. With the improvement of prehospital care, EMSS, and in-hospital care, there will be a decrease in DOA patients.

Adolescent↗

PubMed1994

The role of a pentanucleotide repeat sequence, AGGGAAGGGA, in the regulation of JC virus DNA replication.

The human polyomavirus JCV differs from other papovaviruses in its narrow host range and tissue tropism for human glial cells. It is believed that the cell-specific tropism of JCV to glial cells rests, at least in part, in transcription of the viral early gene that encodes the large tumor antigen (T-antigen). The secondary stage, however, which restricts the replication cycle of JCV to primate cells, is controlled at the level of viral DNA replication. In this study, we demonstrate that a cis-acting transcription regulatory element encompassing the pentanucleotide repeat sequence AGGGAAGGGA (penta), which is located in close proximity to the origin of DNA replication, plays an important role in the replication of viral DNA mediated by the JCV T-antigen, but not T-antigen derived from SV40. Analysis of DNA structure by diethyl pyrocarbonate (DEPC) has revealed that mutations within the penta which affect DNA replication also alter the structure of the neighboring A+T-rich region. These results suggest that, in addition to the regulatory role in viral gene expression, the penta may function as a DNA structural element which is important for JCV DNA replication mediated by the JCV T-antigen.

Animals↗

PubMed1994

Cell kinetics and radiosensitivity of cervical squamous cell carcinoma.

Flow cytometry analyses of tumors from 12 patients with cervical squamous cell carcinoma under radiotherapy were performed in this preliminary study. Six patients with a high (> 10%) G2/M fraction before treatment showed greater than 50% tumor reduction after initial 2000 cGy radiotherapy. Only two out of six patients with a low (< 10%) G2/M fraction before treatment responded favorably and three of them already had recurrence during the follow-up period of 33-40 months. Hyperploidy (DNA index > 1.1) was observed in 5 patients; all of them responded well to radiotherapy in contrast to three out of seven diploid tumors.

Carcinoma, Squamous Cell↗

PubMed1994

The genotypes and prognostic significance of human papillomaviruses in cervical cancer.

An integrated study on the role of human papillomaviruses (HPV) in cervical cancer has been conducted. Out of a total of 433 cases of cervical cancer, HPV-DNA was detected in 342 (79%) using the polymerase chain reaction (PCR). The incidence of HPV infection was not significantly related to histological types, although a lower incidence was noted in adenocarcinoma cases. The incidence of lymph node (LN) metastasis in adenosquamous carcinoma (55.6%) was significantly higher than in squamous cell carcinoma (SCC) and adenocarcinoma. HPV 16 was detected significantly more often in SCC than in adenocarcinoma. In contrast, HPV 18 was detected more often in adenocarcinoma than in SCC. As a whole, pelvic LN metastases were found in 24.3% of HPV+ cases, significantly higher than 11% of HPV- cases. However, the significant association of HPV-DNA with LN metastasis was only noted in stage I but not stage II. As far as histological types were concerned, the incidence of positive LN was: HPV+ SCC > HPV- SCC (p < 0.01), whereas HPV- adenocarcinoma > HPV+ adenocarcinoma (p = 0.12). Genotypes of HPV did not have any effect on nodal status. The presence of types of HPV were not associated with tumor size and distribution of clinical stage. Our results suggest that the prognostic significance of HPV-DNA on nodal status is dependent on histological types while the genotypes of HPV cannot account for prognostic significance in cervical cancer.

Adult↗

PubMed1994

The alpha 1-subunit of skeletal muscle L-type Ca channels is the key target for regulation by A-kinase and protein phosphatase-1C.

Despite the fact that the phosphorylation-mediated regulation of L-type Ca channels is viewed as a model of ion channel regulation, much remains to be learned about the protein phosphorylation and dephosphorylation reactions that underlie the regulation of the channels. The channel isoform most well studied biochemically is that expressed in skeletal muscle. The alpha 1- and beta-subunits of this channel isoform are substrates for protein kinase A, but it is unknown if phosphorylation or dephosphorylation of both subunits contributes to altered channel properties. Here, we report experiments in which the alpha 1- and beta-subunits were differentially phosphorylated by protein kinase A and dephosphorylated by protein phosphatase 1c under conditions that led to channel regulation. The results suggest that the alpha 1-subunit plays a key role in the phosphorylation and dephosphorylation-dependent regulation of the L-type Ca channels from skeletal muscle.

Animals↗

PubMed1994

Human papillomavirus DNA and p53 status in stage IB bulky cervical cancer.

We used the polymerase chain reaction (PCR) to study the presence and typing of human papillomavirus (HPV) DNA, and PCR/single-strand confirmation polymorphism to survey the mutations of the p53 gene in exons 5-9 in 26 bulky stage IB cervical cancers. The HPV DNA was present in 20 out of the 21 (95%) squamous-cell carcinoma tissues, including 13 cases of HPV-16, 0 case of HPV-18, and 7 cases of other HPV types. In the other 5 adenocarcinoma tissues, 3 had HPV type-18 DNA and 2 had no detectable HPV DNA. The distribution of HPV DNA in bulky tumors was not statistically different from that in the other 228 squamous-cell carcinomas and 23 adenocarcinomas of smaller size operated upon during the same period. Out of the 26 patients, 9 (35%) had lymph node metastasis at the time of operation. During the follow-up period ranging from 19 to 48 months, 9 patients had recurrence and 7 of them died of disease. The distribution of HPV types was not related to the prognosis in these patients. There were no p53 mutations detected in all the 26 samples. Thus, HPV type and the status of p53 could not serve as additional prognostic factors in stage IB bulky cervical cancers.

Adenocarcinoma↗

PubMed1994

Endoscopic injection sclerotherapy vs. endoscopic variceal ligation in arresting acute variceal bleeding for patients with advanced hepatocellular carcinoma.

Patients with advanced hepatocellular carcinoma and acute esophageal variceal bleeding have a very poor prognosis. To compare the efficacy and complications of sclerotherapy and banding ligation, patients with acute esophageal variceal bleeding and concomitant hepatocellular carcinoma were randomly allocated to receive either sclerotherapy (endoscopic injection sclerotherapy group, 27 patients) or banding ligation (endoscopic variceal ligation group, 30 patients). All patients received treatment within 24 h of index bleeding. Initial control of bleeding was achieved in 41% of the endoscopic injection sclerotherapy group and 87% of the endoscopic variceal ligation group (p < 0.001). The re-bleeding rates were 73% and 42%, respectively (p < 0.05). The amount of blood transfused during the week after treatment was significantly higher in the endoscopic injection sclerotherapy than in the endoscopic variceal ligation group (3.9 +/- 1.5 vs. 1.5 +/- 0.8 units, respectively) (p < 0.01). Major complications were more often encountered in the endoscopic injection sclerotherapy group (22%) than in the endoscopic variceal ligation group (3%) (p < 0.05). Twenty-three patients in the endoscopic injection sclerotherapy group and 25 patients in the endoscopic variceal ligation group have so far died. The mean survival was 25 +/- 16 days in the endoscopic injection sclerotherapy group and 49 +/- 14 days in the endoscopic variceal ligation group (p < 0.05). Variceal bleeding was the main cause of mortality in the endoscopic injection sclerotherapy group (70%), whereas in the endoscopic variceal ligation group, hepatic failure (48%), rather than variceal bleeding (28%), was the major cause.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1994

The healthcare volunteer.

Every year, volunteers contribute billions of dollars worth of time to the healthcare industry. Despite their contributions, however, little is known about who these volunteers are, what they do, why they volunteer, as well as the costs and benefits they bring to institutions. This article examines these and other characteristics of the healthcare volunteer.

Adult↗

PubMed1994

Quantification of vitamin C requirements for juvenile shrimp (Penaeus monodon) using polyphosphorylated L-ascorbic acid.

The vitamin C requirements of marine shrimp (Penaeus monodon) for optimal growth were evaluated in a 15-wk feeding trial using polyphosphorylated L-ascorbic acid (C2PP), a stable derivative of L-ascorbic acid (C1). Juvenile shrimp (0.55 +/- 0.01 g) were fed purified diets containing graded levels (0, 50, 100, 200 and 400 mg/kg diet) of supplemental C2PP or a high dosage of C1 (2500 mg/kg diet). Their weight gain, survival, feed efficiency and C1 storage in hepatopancreas and muscle were used to quantify the requirements. The growth of the shrimp fed the unsupplemented diet was significantly lower than those of the supplemented groups except the 100 mg C2PP/kg diet group. The C1 concentrations in muscle and hepatopancreas were greatest in shrimp fed 200 or 400 C2PP mg/kg diet. The dietary level required for juvenile P. monodon was found to be 209 mg/kg diet, based on the broken-line model analysis of weight gain, and was 220 mg/kg diet and 210 mg/kg diet, based on the analyses of C1 concentrations of hepatopancreas and muscle, respectively. Shrimp fed unsupplemented diet showed a significantly higher mortality than the supplemented groups. Most of the shrimp in the unsupplemented group that died suffered incomplete molting. No other overt deficiency sign was observed in any group.

Animals↗

PubMed1994

Cell-autonomous cytokinin-independent growth of tobacco cells transformed by Agrobacterium tumefaciens strains lacking the cytokinin biosynthesis gene.

Mutations at the cytokinin biosynthesis locus (tmr) of Agrobacterium tumefaciens usually result in strains that induce tumors exhibiting the rooty phenotype associated with high auxin-to-cytokinin ratios. However, tobacco (Nicotiana tabacum cv Havana 425) leaf disc explants responded to tmr- mutant strain A356 by producing rapidly growing, unorganized tumors, indicating that these lines can grow in a cytokinin-independent fashion despite the absence of a functional tmr gene. Several methods have been used to characterize the physiological and cellular basis of this phenotype. The results indicate that tmr- tumors have a physiologically distinct mechanism for cytokinin-independent growth in comparison to tumors induced by wild-type bacteria. The cytokinin-independent phenotype of the tmr- transformants appears to be cell autonomous in nature: only the transformed cells and their progeny were capable of cytokinin-independent growth. Specifically, the tmr- tumors did not accumulate cytokinin, and clonal analysis indicated the tmr- transformed cells were not capable of stimulating the growth of neighboring nontransformed cells. Finally, the cytokinin-independent phenotype of the tmr- transformants was shown to be cold sensitive, whereas the wild-type tumors exhibited a cold-resistant cytokinin-independent phenotype. Potential mechanisms for this novel form of cytokinin-independent growth, including the role of the dehydrodiconiferyl alcohol glucosides found in both tumor types, are discussed.

Agrobacterium tumefaciens↗