Location of Local Recurrences Post-Prostatectomy Detected by 18F-DCPFyL and Implications for Salvage Radiotherapy Target Volumes

PURPOSE/OBJECTIVE(S)

The use of prostate-specific membrane antigen (PSMA) PET scans have improved detection of recurrent prostate cancer for biochemical failure post-prostatectomy. The primary aim of this study is to assess the location of local recurrences for PSMA PET positive disease post-prostatectomy relative to anatomical landmarks and to inform salvage radiotherapy contouring guidelines.

MATERIALS/METHODS

This is a retrospective study of patients who underwent a staging PSMA PET-CT scan with 18F-DCFPyL tracer. Eligible patients included men with biochemical recurrence (PSA >0.2ng/mL) post-prostatectomy for prostate adenocarcinoma. PSMA positive local disease (GTV) was marked on the CT scan of the PSMA PET/CT, using the PSMA PET scan fused as the secondary dataset. Reference structures were contoured to compare the positional relationship to the GTV local recurrence. Centroids of each GTV position were measured to the closest border of the reference structures and distance measured.

RESULTS

Forty-five patients had a local recurrence on PSMA PET, 28/45 with prostate bed recurrence and 17/45 with seminal vesicle bed recurrence. The median age was 72.7 years, median pre-treatment PSA 0.515 ng/ml (0.2-11.1), pT2 in 37.8% and pT3 in 62.2, ISUP G2-3 was 66.7%, ISUP 4-5 29.6%, 67% ECE, 15.4% SV involvement and 40% positive margin. For prostate bed recurrences, 93.6% of GTVs were within 15mm from the inferior border of pubic symphysis (median 3.3mm [-9.8-15.4]), 83.9% within 10mm from the VUA (median 3.3mm [-17.4-15.9]), and 80.6% were greater than 10mm from the most superior slice of the penile bulb (median 16.4mm [1-29.5]). Laterally, 83.9% of recurrences were within 10mm of midline and 41.9% within 5mm (median 3.3mm [-13.56-11.59]) and all were contained within levator, 35.5% within 5mm (median 7.7 [1-22.6]) of the medial muscle border. 29.0% were within 5mm from the anterior edge of the rectal wall (median -7mm [-32.3-0.5]). Seminal vesicle bed recurrences were within 17.5mm of upper border of pubic symphysis for 88.9% of patients (median -4.69mm[-30.8to18.2]), 100% were more than 7.5mm inferiorly from the vas deferens (median-22.1mm[-32.7to-7.7]). Laterally, 100% recurrences were more than 7.5mm medial from obturator internus (median 5.37mm [-23.1to37.8]), and 88.9% were more than 10mm from midline (median 23.1mm [2.0-36.6]).

CONCLUSION

The 18F-DCFPyL PSMA PET local recurrences can provide detailed localization of prostate bed and seminal vesicle recurrences. Our data can inform contouring guidelines for salvage radiotherapy to the prostate bed, particularly when using anatomical landmarks to define cranio-caudal extent of target volumes. For target volume laterally, the medial wall of levator ani would encompass all prostate bed recurrences, and no seminal vesicles recurrences were seen at the medial border of the obturator internus muscle.

Brain microglia serve as a persistent HIV reservoir despite durable antiretroviral therapy

Brain microglia (MG) may serve as a human immunodeficiency virus 1 (HIV) reservoir and ignite rebound viremia following cessation of antiretroviral therapy (ART), but they have yet to be proven to harbor replication-competent HIV. Here, we isolated brain myeloid cells (BrMCs) from nonhuman primates and rapid autopsy of people with HIV (PWH) on ART and sought evidence of persistent viral infection. BrMCs predominantly displayed microglial markers, in which up to 99.9% of the BrMCs were TMEM119+ MG. Total and integrated SIV or HIV DNA was detectable in the MG, with low levels of cell-associated viral RNA. Provirus in MG was highly sensitive to epigenetic inhibition. Outgrowth virus from parietal cortex MG in an individual with HIV productively infected both MG and PBMCs. This inducible, replication-competent virus and virus from basal ganglia proviral DNA were closely related but highly divergent from variants in peripheral compartments. Phenotyping studies characterized brain-derived virus as macrophage tropic based on the ability of the virus to infect cells expressing low levels of CD4. The lack of genetic diversity in virus from the brain suggests that this macrophage-tropic lineage quickly colonized brain regions. These data demonstrate that MG harbor replication-competent HIV and serve as a persistent reservoir in the brain.

Crotonylation sensitizes IAPi-induced disruption of latent HIV by enhancing p100 cleavage into p52

The eradication of HIV infection is difficult to achieve because of stable viral reservoirs. Here, we show that crotonylation enhances AZD5582-induced noncanonical NF-κB (ncNF-κB) signaling, further augmenting HIV latency reversal in Jurkat and U1 cell line models of latency, HIV latently infected primary CD4+ T cells and resting CD4+ T cells isolated from people living with HIV. Crotonylation upregulated the levels of the active p52 subunit of NF-κB following AZD5582. Biochemical analyses suggest that the ubiquitin E3 ligase TRIM27 is involved in enhanced p100 cleavage to p52. When TRIM27 was depleted, AZD5582-induced HIV latency reversal was reduced. TRIM27 small interfering RNA (siRNA) knockdown reduced both p100 and p52 levels without inhibiting p100 transcription, indicating that TRIM27 not only acts on p100 cleavage but also may impact p100/p52 stability. These observations reveal the complexity of HIV transcriptional machinery, particularly of NF-κB.

Microglia-Specific Promoter Activities of HEXB Gene

Adeno-associated virus (AAV)-mediated genetic targeting of microglia remains a challenge. Overcoming this hurdle is essential for gene editing in the central nervous system (CNS). Here, we characterized the minimal/native promoter of the HEXB gene, which is known to be specifically and stably expressed in the microglia during homeostatic and pathological conditions. Dual reporter and serial deletion assays identified the critical role of the natural 5' untranslated region (-97 bp related to the first ATG) in driving transcriptional activity of the mouse Hexb gene. The native promoter region of mouse, human, and monkey HEXB are located at -135, -134, and -170 bp to the first ATG, respectively. These promoters were highly active and specific in microglia with strong cross-species transcriptional activities, but did not exhibit activity in primary astrocytes. In addition, we identified a 135 bp promoter of CD68 gene that was highly active in microglia but not in astrocytes. Considering that HEXB is specifically expressed in microglia, these data suggest that the newly characterized microglia-specific HEXB minimal/native promoter can be an ideal candidate for microglia-targeting AAV gene therapy in the CNS.

Human Immunodeficiency Virus-1 Latency Reversal via the Induction of Early Growth Response Protein 1 to Bypass Protein Kinase C Agonist-Associated Immune Activation

Human Immunodeficiency Virus-1 (HIV) remains a global health challenge due to the latent HIV reservoirs in people living with HIV (PLWH). Dormant yet replication competent HIV harbored in the resting CD4+ T cells cannot be purged by antiretroviral therapy (ART) alone. One approach of HIV cure is the "Kick and Kill" strategy where latency reversal agents (LRAs) have been implemented to disrupt latent HIV, expecting to eradicate HIV reservoirs by viral cytopathic effect or immune-mediated clearance. Protein Kinase C agonists (PKCa), a family of LRAs, have demonstrated the ability to disrupt latent HIV to an extent. However, the toxicity of PKCa remains a concern in vivo. Early growth response protein 1 (EGR1) is a downstream target of PKCa during latency reversal. Here, we show that PKCa induces EGR1 which directly drives Tat-dependent HIV transcription. Resveratrol, a natural phytoalexin found in grapes and various plants, induces Egr1 expression and disrupts latent HIV in several HIV latency models in vitro and in CD4+ T cells isolated from ART-suppressed PLWH ex vivo. In the primary CD4+ T cells, resveratrol does not induce immune activation at the dosage that it reverses latency, indicating that targeting EGR1 may be able to reverse latency and bypass PKCa-induced immune activation.

A Plausible Link of TMPRSS2/ACE2/AR Signaling to Male Mortality during the COVID-19 Pandemic in the United States

The COVID-19 pandemic continues around the world, where the United States is among the worst in terms of both morbidity and fatality of the viral infection. We aim to investigate the plausible link of tissue SARS-CoV-2 viral entry gene expression, such as TMPRSS2 and ACE2, with infection and death by gender during the COVID-19 pandemic in the United States. We find a significantly higher incidence of COVID-19 death in men than in women, even though SARS-CoV-2 infection in women is higher than in men. We discover that the expression of TMPRSS2 and ACE2 in intestine, but not in lung, tends to be positively associated with the incidence of SARS-CoV-2 infection in men. In contrast, the high incidence of death in men is negatively correlated with TMPRSS2/ACE2 expression in intestine. Strikingly, the correlation of TMPRSS2/ACE2 expression with SARS-CoV-2 infection and death is the opposite in females, compared with that in males. Interestingly, male hormone signaling seems to be involved in mortality, as the low expression of testosterone receptor AR in the prostate contributes to death in men according to age. These observations point to a plausible contribution of male hormone metabolism in the regulation of TMPRSS2/ACE2 signaling to fatality by SARS-CoV-2 infection in men.

NF-κB sub-pathways and HIV cure: A revisit

HIV cure is thwarted by the presence of quiescent yet replication competent HIV-1 (HIV). Antiretroviral therapy (ART) is unable to eradicate reservoirs, and upon cessation of ART, HIV will rebound. This review encompasses the curative strategies of HIV in the context of NF-κB sub-pathways that are currently exploited and demonstrate promise in the disruption of latent HIV. Canonical NF-κB signaling has long been established to drive HIV proviral expression while noncanonical NF-κB signaling, a novel and perhaps more desirable mechanism of latency reversal due to its unique characteristics, has recently been shown to also promote HIV expression from latency. Furthermore, we discuss the previously unrecognized upstream signaling of NF-κB as a new avenue for exploration of a functional cure of HIV.

Learning clinical procedures through Internet visual resources: a qualitative study amongst undergraduate students

OBJECTIVE

Acquiring competency in performing clinical procedures is central to professional education of healthcare providers. Internet visual resources (IVR), defined as visual materials openly accessible on public websites, provides a new channel to learn clinical procedures. This qualitative study aimed to profile the experience and opinions of undergraduate students (in dentistry, medicine and nursing) in learning clinical procedures through IVR.

METHODS

From clinical degree programmes (Bachelor of Dental Surgery, Bachelor of Medicine, Bachelor of Surgery, and Bachelor of Nursing) of University of Hong Kong, 31 students were recruited to join six focus group discussions, which were transcribed and subjected to thematic analysis using inductive method, in which themes emerge from data.

FINDINGS

Students actively looked for IVRs through various means and used them for pre-clinical preparation, post-clinical revision, learning simple and advanced procedures, exploring alternative and updated techniques, and benchmarking against international peers. IVRs were valued for their visual stimulation, inclusion of a wide variety of real-life cases, convenience in access, user-friendliness and time-saving features. Students tended to share and discuss IVRs with their peers rather than with tutors, even when contents deviated from school teaching or faculty's e-learning materials. When doubts persisted, they chose to follow faculty guidelines for examination purpose. Students were frustrated sometimes by difficulties in judging the scientific quality, lack of immediate interactive discussions and loosely structured presentations in some IVRs. Teachers' attitudes towards IVR appeared to vary greatly.

CONCLUSION

Despite the wide spectrum of experience and opinions, IVR was generally viewed by undergraduates from across clinical faculties as enhancing their clinical confidence and self-perceived competency, enriching their learning experience and serving as an important supplement to formal learning in the planned curriculum.

Should follow-up biopsies for men on active surveillance for prostate cancer be restricted to limited templates?

OBJECTIVE

To investigate if prostate biopsy templates with fewer cores can be used during active surveillance (AS) for prostate cancer.

METHODS

At present, we use an AS protocol template (ASPT) consisting of 13-17 cores. We hypothesize in the setting of known cancer, sextant (6 cores) or standard extended (10-12 cores) templates, could be used with similar effect. We identified patients in our referral institution database (1997-2009) with entry prostate-specific antigen <10 ng/mL, stage ≤cT2, Gleason sum ≤6, ≤3 cores positive for cancer, <50% of single core involved, and age ≤75 years (N = 272). Patients fulfilling standard criteria for pathologic reclassification (N = 94) at any follow-up biopsy were selected for evaluation. By mapping tumor location on the pathologic reclassification determining biopsy, hypothetical scenarios of sextant or standard extended templates (SET) were compared with our ASPT and examined for frequency of cancer detection and pathologic reclassification.

RESULTS

For the 94 patients analyzed, the median number of cores taken was 9.7 (6-22) at baseline and 15 (14-17) for the reclassification biopsy. The median time between baseline and the pathologic reclassification determining biopsy was 15.4 months. Analysis of subgroupings showed that sextant template would identify 84% of cancers and 47.9% of the reclassification events, whereas SET detected 99% of cancers and 81.9% of patients who pathologically reclassified. When only considering Gleason sum ≥7 related progression events, SET found 16.2% less (n = 57) compared with ASPT (n = 68).

CONCLUSION

When monitoring patients on AS, a 13-17 core template detects more pathologic reclassification than standard sextant (18.1%) or extended (52.1%) biopsy templates.

Ultrafast insulator–metal phase transition in vanadium dioxide studied using optical pump–terahertz probe spectroscopy

We studied the ultrafast dynamic behavior of the photoinduced insulator–metal phase transition in VO2 thin film using optical pump–terahertz probe spectroscopy with different excitation fluences and at different temperatures. We observed two processes in the insulator–metal phase transition in VO2: a fast process and a slow process. The fast process is a nonthermal process, which is ascribed to the nucleation of the metal phase, while the slow process is strongly affected by temperature and is ascribed to the thermally driven growth and coalescence of metal domains in VO2. The transient complex conductivity spectra at different delay times are also investigated.

Enhancement of bandgap emission of Pt-capped MgZnO films: important role of light extraction versus exciton-plasmon coupling

We present on a systematic study of the contribution of surface plasmon (SP) coupling and light extraction toward emission enhancement of Platinum (Pt) nano-patterns capped MgZnO films. Time resolved Photoluminescence (PL) results indicate that the Pt coating can greatly reduces the non-radiative recombination rate by passivation of surface states, making the decay slow down. Temperature dependence of the integrated photoluminescence intensity reveals that the Pt nano-patterns can offer a large amount of light transfer and scattering, which enormously increase the light extraction efficiency up to 3.8-fold. These results indicate that the increased light extraction efficiency caused by surface modification via Pt coating rather than SP coupling plays a dominant role in increasing bandgap emission of MgZnO film.

Molecular analysis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency in Hong Kong Chinese patients

BACKGROUND

Congenital adrenal hyperplasia (CAH) caused by 21-hydroxylase deficiency (21OHD) is an autosomal recessive disorder due to mutation in the CYP21A2 gene.

OBJECTIVE

To elucidate the genetic basis of 21-hydroxylase-deficient CAH in Hong Kong Chinese patients.

PATIENTS AND METHODS

Mutational analysis of the CYP21A2 gene was performed on 35 Hong Kong Chinese patients with 21OHD using direct DNA sequencing and multiplex ligation-dependent probe amplification (MLPA).

RESULTS

The genetic findings of 21 male and 14 female patients are the following: c.293-13A/C>G (intron 2 splice site; 20 alleles), p.I172N (13), p.R356W (7), p.Q318X (4). A total of 20 mutant alleles contained gross deletion/conversion of all or part of the CYP21A2 gene. A novel mutation, c.1367delA (p.D456fs), was detected in one patient. One patient had only a heterozygous mutation detected. Out of 35 patients, 16 would have been incorrectly genotyped if either DNA sequencing or MLPA alone was used for molecular analysis.

CONCLUSIONS

The frequency of various mutations in the studied patients differs from those reported in other Asian populations. Gross deletion/conversion accounts for nearly one-third of the genetic defects. Therefore, laboratories must include methods for detecting point mutations as well as gross deletions/conversions to avoid misinterpretation of genotype. Genotyping has increasingly been proven to be a useful tool for supplementing, if not replacing, hormonal profiling for the diagnosis of 21OHD.

Cloning of cDNA for the contact site A glycoprotein of Dictyostelium discoideum

A cell surface glycoprotein of Dictyostelium discoideum with M(r) 80,000 (gp80) has been shown to mediate the formation of the developmentally acquired EDTA-resistant cell-cell binding sites termed contact sites A. We have isolated cDNA clones encoding gp80 by immunological screening of an expression library prepared in Escherichia coli. Double-stranded cDNA was prepared from poly(A)(+) RNA isolated from cells at 8 hr of development and cloned into the bacteriophage expression vector lambdagt11. Two recombinant phages containing cDNA inserts of 1.2 and 0.8 kilobases were isolated and shown to contain sequences coding for gp80 by the immunoselect assay. Partial DNA sequence analysis also confirmed that one of these cDNA clones, lambdaDdgp80c-19, contained the coding sequence for the amino terminus of gp80. DNA-RNA hybridization showed that the insert of lambdaDdgp80c-19 hybridized to a single mRNA transcript of approximately 2.0 kilobases. gp80 mRNA became detectable after 6 hr of development, reached its maximum level at 9 hr, and dropped to a negligible level by 15 hr. This pattern of mRNA accumulation corresponded closely to that of gp80 synthesis in D. discoideum cells, suggesting that gp80 expression is regulated at the transcriptional level.

Heterostructures of germanium nanowires and germanium-silicon oxide nanotubes and growth mechanisms

We report on a method to fabricate one-dimensional heterostructures of germanium nanowires (GeNWs) and germanium-silicon oxide nanotubes (GeSiO(x)NTs). The synthesis of the wire-tube heterostructures is carried out using a simple furnace set-up with germanium tetraiodide and germanium powders as growth precursors, gold-dotted silicon wafers as substrates and by controlling the temperature ramp rate/sequence of the growth precursors. Two types of wire-tube heterostructures resulting from distinct growth mechanisms are obtained. The type-1 heterostructure consists of a GeNW, grown via a gold-catalyzed vapour-liquid-solid process, at the lower end and a GeSiO(x)NT at the upper end. In contrast, the type-2 heterostructure is made up of a solid wire at the upper end and a hollow tube at the lower end. The solid wire portion of the type-2 heterostructure is formed through an oxide-assisted growth process.

Morphology-controlled synthesis and a comparative study of the physical properties of SnO2 nanostructures: from ultrathin nanowires to ultrawide nanobelts

Controlled synthesis of one-dimensional materials, such as nanowires and nanobelts, is of vital importance for achieving the desired properties and fabricating functional devices. We report a systematic investigation of the vapor transport growth of one-dimensional SnO(2) nanostructures, aiming to achieve precise morphology control. SnO(2) nanowires are obtained when SnO(2) mixed with graphite is used as the source material; adding TiO(2) into the source reliably leads to the formation of nanobelts. Ti-induced modification of crystal surface energy is proposed to be the origin of the morphology change. In addition, control of the lateral dimensions of both SnO(2) nanowires (from approximately 15 to approximately 115 nm in diameter) and nanobelts (from approximately 30 nm to approximately 2 microm in width) is achieved by adjusting the growth conditions. The physical properties of SnO(2) nanowires and nanobelts are further characterized and compared using room temperature photoluminescence, resonant Raman scattering, and field emission measurements.

Allele frequencies and haplotypes of 12 Y-STR loci for the local Chinese population in Hong Kong

Haplotype frequencies were established for 12 Y-chromosome STR loci, including all loci recommended by Scientific Working Group on DNA Analysis Methods Y-STR Subcommittee (DYS391, DYS389I/II, DYS439, DYS393, DYS390, DYS385a/b, DYS438, DYS19 and DYS392) plus DYS437, in the local Chinese population in Hong Kong. In a sample of 481 unrelated males, it was possible to define 424 different haplotypes of which 388 were unique, 26 was found in two individuals, 2 were shared in three individuals, 5 were shared in four individuals and 3 were shared in five individuals. The allele diversity values for each locus ranged from 0.4273 (DYS438) to 0.9555 (DYS385a/b). The observed haplotype diversity value and discrimination capacity were 0.9992 and 0.8815, respectively. In a genetic study of these unrelated males, triple alleles were found at the DYS358 locus in six individuals. The combined Y-chromosome STR polymorphisms provide a powerful discrimination tool for routine forensic applications.

Glycerol kinase deficiency presenting with hypodipsia, osmotic diuresis and severe hypernatraemia

A Chinese boy with glycerol kinase deficiency is reported. His presentation with severe hypernatraemia secondary to hypodipsia and glycerol-induced osmotic diuresis is unusual and not previously described in the literature.

Changes in heart rate and R-wave amplitude with posture

BACKGROUND

Effect of gravity on heart rate and blood pressure are well documented but the effect of posture on R-wave amplitude has not been studied.

AIM

To investigate the effect of posture on the heart rate (HR) and R-wave amplitude (RWA).

METHODS

The electrocardiograph (ECG) was recorded in 20 young subjects on two occasions. A 5 minute recording of resting ECG was taken with the subject adopting the following postural cycle: lying, sitting, standing, sitting and lying positions.

RESULTS

The standing HR was significantly higher than that in sitting and lying positions, but the RWA was significantly lower in standing compared to the sitting and lying postures. The HR significantly increased at the initial phase of postural changes, irrespective of the position. For example, the HR increased from lying to sitting (66.6+/-2.3 to 85.0+/-10.9 beat x min(-1)) but also increased when changed from sitting to lying (70.6+/-10.6 to 85.2+/-8.7 beat x min(-1)).

CONCLUSION

Body posture has an effect on HR and RWA. The changes are probably related to orthostatic haemodynamic stress as well as changes in cardiac electrical axis. Whether the cause of the initial increase in the HR during postural change was attributed to skeletal muscle reflex or venous return requires further investigation.

Childhood thrombocytopenia associated with Graves disease is distinct from idiopathic thrombocytopenic purpura

The authors report a case of thrombocytopenia in a 10-year-old Chinese girl who was also found to have Graves disease 6 months later. The clinical, hematologic, and bone marrow features were indistinguishable from chronic idiopathic thrombocytopenic purpura, but the patient's platelet counts were normalized concurrently with the control of thyrotoxicosis with carbimazole treatment. Childhood thrombocytopenia associated with autoimmune thyroid disease is a rarely reported condition and its management differs from that of idiopathic thrombocytopenic purpura.

STR data for the PowerPlex 16 loci for the Chinese population in Hong Kong

Allele frequencies for the 15 STR loci included in the PowerPlex 16 kit were obtained from a sample of 247 unrelated Chinese in Hong Kong.

Surgical infections in patients with chronic renal failure

Patients with chronic renal failure and uremia have impaired host defenses and wound healing that can lead to an increased risk of infection in addition to a frequent need for surgical procedures with synthetic grafts and catheters. Antibiotic therapy plus timely surgical intervention in removal of infected grafts and catheters is crucial for infection control and patient survival. Other surgical infections, such as wound problems, intraabdominal infections, fungal infections, diabetic foot ulcers, and necrotizing soft tissue infections must be attended to promptly.

Improved survival with screening for hepatocellular carcinoma

Hepatocellular cancer (HCC) is a frequent cause of cancer death worldwide. Although successful screening programs exist in Asian countries, the role for screening in the United States is not clear. The purpose of this study is to determine if screening has an effect on survival in a predominantly Asian population in Hawaii. We retrospectively reviewed cases of HCC from 1993 to 1998 for demographic data, risk factors, symptoms, stage, treatment, and survival. Patients were divided into 3 groups according to presentation: symptomatic (S), asymptomatic (A), and asymptomatic but screened for disease (A/Sc). Kaplan-Meier analysis was performed on overall survival by group. Ninety-one patients were referred for HCC. There were 56 patients in group S, 19 patients in group A, and 16 patients in group A/Sc. Patients in group A/Sc survived significantly longer than those in group S (P =.009), with the former group having a median survival of 1,399 versus 234 days for group S. Median survival for group A was 545 days and did not differ significantly from the other groups. Patients who are asymptomatic and screened for HCC have an increased survival compared with those patients who present with symptoms. This may justify the use of a formal screening program for HCC in Hawaii, but we would need to investigate this prospectively.

Epidemiology of diabetes mellitus in children in Hong Kong: the Hong Kong childhood diabetes register

OBJECTIVES

To establish a registry for Chinese children with onset of type 1 (insulin dependent) diabetes mellitus before 15 years of age and to determine the incidence of childhood onset type 1 diabetes mellitus in Chinese children in Hong Kong.

RESEARCH DESIGN AND METHODS

A registry was established in 1997 to collect childhood diabetes cases retrospectively from all districts in Hong Kong. The study included all newly diagnosed cases of diabetes with onset < 15 yr of age from 1st January 1984 to 31 December 1996. Primary ascertainment was based on review of medical records at all regional public hospitals in Hong Kong and survey of all the registered practitioners in Hong Kong. The secondary source of validation was made impractical, if not impossible, because of the recent implementation of the Personal Data Privacy Ordinance in Hong Kong.

RESULTS

A total of 255 diabetic cases were identified, 227 type 1 diabetes mellitus (218 were Chinese), 18 type 2 diabetes mellitus and 11 secondary diabetes. 246 patients were Chinese and 9 non-Chinese. The age-standardized incidence of type 1 and type 2 diabetes mellitus in southern Chinese children in Hong Kong was 1.4/100,000/yr and 0.1/100,000/yr respectively for children < 15 yr of age during the study period. The incidence rates for type 1 diabetes were 0.9, 1.5 and 1.7 per 100,000/yr for 0-4 years, 5 to 9 years and 10 to 14 years age-groups respectively. The incidence for males was 1.2/100,000/yr and for females 1.7/100,000/yr. A significant increase in the incidence was demonstrated during the study period by simple linear regression (slope 0.14/100,000/year, r2 = 0.73, p = 0.0002)

CONCLUSIONS

A diabetic registry is established in Hong Kong. This study documents a very low incidence rate of childhood type 1 diabetes mellitus in southern Chinese children in Hong Kong and we have seen an increasing incidence of the disease in the past 13 years.

Two novel myogenic factors identified and isolated by sequential isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis

A number of environmental factors were used experimentally to enhance myogenesis during muscle regeneration; however, many hormones and growth factors have been shown to have the ability to increase the rate of satellite cell division, but they only work on satellite cells that are already active in many animal experiments. Recently, the crushed muscle extract (CME) of rats was found to be able to trigger dormant adult rat satellite cells to re-enter the cell mytogenic cycle; however, the identity of the active factors present in rat CME remains unknown. In the present study, the CME was fractionated by the strategy of sequential isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) coupled with functional analysis by myoblast culture. Two satellite cell-specific myogenic factors were identified and purified from CME by this strategy. One of the factors has a molecular mass of around 7 kDa and another about 39 kDa. The factor of 39 kDa could be retained in heparin-Sepharose column and eluted with phosphate-buffered saline (PBS) containing 1 M NaCl, but the 7 kDa factor did not bind to the heparin column. These two purified myogenic factors could synergistically trigger the proliferation and differentiation of dormant satellite cells, whose progenies subsequently fuse in vitro, or fuse to pre-existing partially damaged muscle fibers to form full repair of the damaged muscle fibers or to form new myotubes to replace the completely damaged muscle fibers during the cascade of muscle healing and regeneration in vivo. The identities of these two myogenic factors are under study.

Differential cytokine modulation and T cell activation by two distinct classes of thalidomide analogues that are potent inhibitors of TNF-alpha

TNF-alpha mediates both protective and detrimental manifestations of the host immune response. Our previous work has shown thalidomide to be a relatively selective inhibitor of TNF-alpha production in vivo and in vitro. Additionally, we have recently reported that thalidomide exerts a costimulatory effect on T cell responses. To develop thalidomide analogues with increased anti-TNF-alpha activity and reduced or absent toxicities, novel TNF-alpha inhibitors were designed and synthesized. When a selected group of these compounds was examined for their immunomodulatory activities, different patterns of cytokine modulation were revealed. The tested compounds segregated into two distinct classes: one class of compounds, shown to be potent phosphodiesterase 4 inhibitors, inhibited TNF-alpha production, increased IL-10 production by LPS-induced PBMC, and had little effect on T cell activation; the other class of compounds, similar to thalidomide, were not phosphodiesterase 4 inhibitors and markedly stimulated T cell proliferation and IL-2 and IFN-gamma production. These compounds inhibited TNF-alpha, IL-1beta, and IL-6 and greatly increased IL-10 production by LPS-induced PBMC. Similar to thalidomide, the effect of these agents on IL-12 production was dichotomous; IL-12 was inhibited when PBMC were stimulated with LPS but increased when cells were stimulated by cross-linking the TCR. The latter effect was associated with increased T cell CD40 ligand expression. The distinct immunomodulatory activities of these classes of thalidomide analogues may potentially allow them to be used in the clinic for the treatment of different immunopathological disorders.

Amino-substituted thalidomide analogs: potent inhibitors of TNF-alpha production

Thalidomide, (1), is a known inhibitor of TNF-alpha release in LPS stimulated human PBMC. Herein we describe the TNF-alpha inhibitory activity of amino substituted analogs of thalidomide (1) and its isoindolin-1-one analog, EM-12 (2). The 4-amino substituted analogs were found to be potent inhibitors of TNF-alpha release in LPS stimulated human PBMC.

NRG-3 in human breast cancers: activation of multiple erbB family proteins

Ligands of the EGF/Heregulin family control the growth of epithelial cells by binding to receptors of the erbB family. By searching a large database of cDNA sequences at Human Genome Sciences Inc. we have identified a new encoded protein sequence containing all the conserved elements of the EGF/Heregulin family. The same sequence has recently been independently identified as NRG-3. The EGF-like domain of NRG-3 was generated as a recombinant protein in E. coli and used to test the specificity of receptor binding. In human breast cancer cells and in 32D cells transfected by erbB family members, NRG-3 activated multiple erbB family members. These include EGF receptor (erbB1) and erbB4 when expressed individually and erbB2 and erbB3 when expressed together. Recombinant NRG-3 altered the growth of human breast cancer cells growing in vitro. NRG-3 was expressed in cell lines derived from breast cancer. These results indicate that NRG-3 is a potential regulator of normal and malignant breast epithelial cells in vivo.

Thalidomide analogs and PDE4 inhibition

N-Phthaloyl 3-amino-3-arylpropionic acid analogs of thalidomide that are potent inhibitors of tumor necrosis factor-alpha are reported. These compounds were found to be potent inhibitors of phosphodiesterase 4.

Calciphylaxis in patients on hemodialysis: a prevalence study

BACKGROUND

Calciphylaxis is characterized by painful, violaceous, mottled skin lesions (livedo reticularis) that may progress to tissue necrosis, nonhealing ulcers, gangrene, and potentially amputation, sepsis, or death. The prevalence and characteristics of patients who have calciphylaxis need further identification to predict which patients on dialysis may benefit from close monitoring or early surgical intervention.

METHODS

All 242 patients undergoing hemodialysis in an outpatient unit were reviewed retrospectively during a 15-month cross-sectional study of the prevalence and characteristics of calciphylaxis.

RESULTS

Ten patients (prevalence, 4.1%) had calciphylaxis. Patients with calciphylaxis were significantly younger (49 versus 60 years; p = 0.01), had undergone hemodialysis longer (80 versus 20 months; p < 0.0001), and had higher median serum calcium (9.7 versus 9.2 mg/dl; p = 0.03), phosphate (8.2 versus 5.7 mg/dl; p = 0.001), calcium phosphate product (81.5 versus 52.9; p = 0.0004), parathyroid hormone (1496 versus 138 pg/ml; p < 0.0001), and alkaline phosphatase levels (188 versus 89 IU/L; p = 0.0001). Bone surveys were positive in all 10 patients with calciphylaxis compared with 49 (21%) of the 232 patients without calciphylaxis (p < 0.0001). All patients who underwent parathyroidectomy for calciphylaxis had dramatic healing of the ulcers.

CONCLUSIONS

The presence of calciphylaxis is higher among younger patients who had undergone longer periods of hemodialysis. Therefore this group of patients should be monitored aggressively and treated expeditiously for complications of secondary hyperparathyroidism.

The cost of dying of end-stage liver disease

BACKGROUND

The high cost of liver transplantation is well known. The cost of dying of complications of end-stage liver disease (ESLD) without transplant, however, has not been well documented.

METHODS

For a 5-year period (1991-1995), in 153 patients, mean inpatient hospital charges and length of stay were analyzed in 6 groups of patients: (1) patients admitted with the primary diagnosis of esophageal varices, (1a) the subset of group 1 patients who died on this admission, (2) patients admitted to the liver team who died of complications from ESLD, (3) patients who underwent transjugular intrahepatic portosystemic shunts, (4) patients who underwent surgical shunt for bleeding varices, and (5) patients who underwent liver transplantation.

RESULTS

One hundred twenty-nine patients with esophageal varices were hospitalized 13.7 days with a mean charge of $30,980 for each of 202 admissions. Of these, 38 died after 24 days with a mean charge of $67,091. Seven patients admitted to the liver team died of complications of ESLD at $110,576 per admission. Transjugular intrahepatic portosystemic shunt was performed in 17 patients with a mean charge of $43,209. Six patients underwent surgical shunt for $53,994. Mean charge for 7 liver transplantations was $222,968. During the study period, 36.7% of all charges were for patients who died.

CONCLUSIONS

It is difficult to estimate the total cost of ESLD; however, in evaluating inpatient costs, we see that it is expensive and significant amounts are spent on patients who die. Further study is necessary to determine which factors can optimize the cost of ESLD.

Multi-center sestamibi parathyroid imaging study in Hawaii

Technetium-99m (99mTc) sestamibi (MIBI) was first used as a parathyroid imaging agent in Hawaii in 1991. The purpose of this study was to determine the sensitivity and positive predictive value of the MIBI scan in detecting abnormal parathyroid glands. A retrospective, multi-center study from 1992-1994 involving 33 patients in four hospitals showed the overall sensitivity of the MIBI scan for detecting hyperparathyroid disease was 90%. The positive predictive value was 93%. It was more sensitive in detecting adenomas (95%) than hyperplasia (45%). In conclusion, the MIBI scan can be helpful in detecting abnormal parathyroid glands and may be most useful prior to reoperations for persistent and recurrent hyperparathyroidism.

Organization and differential expression of the human monocyte chemoattractant protein 1 receptor gene. Evidence for the role of the carboxyl-terminal tail in receptor trafficking

Two forms of the monocyte chemoattractant protein-1 receptors (the type A monocyte chemoattractant protein 1 (MCP-1) receptor CCR-2A and the type B MCP-1 receptor (CCR-2B) have been recently cloned and found to differ only in their terminal carboxyl tails. Here, we report that the two isoforms are alternatively spliced variants of a single MCP-1 receptor gene. Sequencing of the gene revealed that the 47-amino acid carboxyl tail of CCR2B was located in the same exon as the seven transmembrane domains of the receptor, and the 61-amino acid tail of CCR2A was in a downstream exon. Examination of freshly isolated human monocytes by reverse transcriptase-polymerase chain reaction revealed that CCR2B was the predominant isoform and that message levels of both CCR2A and CCR2B decreased as the monocytes differentiated into macrophages. In stably transfected cell lines, CCR2B trafficked well to the cell surface, but CCR2A was found predominantly in the cytoplasm. Equilibrium binding studies revealed that those CCR2A receptors that successfully trafficked to the cell surface bound MCP-1 with high affinity (Kd = 310 pM), similar to CCR2B. In signaling studies, both CCR2A and CCR2B mediated agonist-dependent calcium mobilization, as well as inhibition of adenylyl cyclase. Creation of chimeras between CCR2A and the human thrombin receptor revealed that the cytoplasmic retention of CCR2A was due to its terminal carboxyl tail. Progressive truncation of the carboxyl tail indicated that a cytoplasmic retention signal(s) was located between residues 316 and 349. These data indicate that the alternatively spliced form of the human MCP-1 receptor (CCR2A) binds MCP-1 with high affinity and is a functional receptor and that expression at the cell surface is controlled by amino acid sequences located in the terminal carboxyl tail.

DNA elements responsive to auxin

Genes induced by the plant hormone auxin are probably involved in the execution of vital cellular functions and developmental processes. Experimental approaches designed to elucidate the molecular mechanisms of auxin action have focused on auxin perception, genetic dissection of the signaling apparatus and specific gene activation. Auxin-responsive promoter elements of early genes provide molecular tools for probing auxin signaling in reverse. Functional analysis of several auxin-specific promoters of unrelated early genes suggests combinatorial utilization of both conserved and variable elements. These elements are arranged into autonomous domains and the combination of such modules generates uniquely composed promoters. Modular promoters allow for auxin-mediated transcriptional responses to be revealed in a tissue- and development-specific manner.

Differential activation of the primary auxin response genes, PS-IAA4/5 and PS-IAA6, during early plant development

The plant growth hormone auxin typified by indoleacetic acid (IAA) transcriptionally activates early genes in pea, PS-IAA4/5 and PS-IAA6, that are members of a multigene family encoding short-lived nuclear proteins. To gain first insight into the biological role of PS-IAA4/5 and PS-IAA6, promoter-beta-glucuronidase (GUS) gene fusions were constructed and their expression during early development of transgenic tobacco seedlings was examined. The comparative analysis reveals spatial and temporal expression patterns of both genes that correlate with cells, tissues, and developmental processes known to be affected by auxin. GUS activity in seedlings of both transgenic lines is located in the root meristem, sites of lateral root initiation and in hypocotyls undergoing rapid elongation. In addition, mutually exclusive cell-specific expression is evident. For instance, PS-IAA4/5-GUS but not PS-IAA6-GUS is expressed in root vascular tissue and in guard cells, whereas only PS-IAA6-GUS activity is detectable in glandular trichomes and redistributes to the elongating side of the hypocotyl upon gravitropic stimulation. Expression of PS-IAA4/5 and PS-IAA6 in elongating, dividing, and differentiating cell types indicates multiple functions during development. The common and yet distinct activity patterns of both genes suggest a combinatorial code of spatio-temporal co-expression of the various PS-IAA4/5-like gene family members in plant development that may mediate cell-specific responses to auxin.

Hepatic cryosurgery: early experience in Hawaii

Liver cancer, both primary and metastatic, is often deemed hopeless and patients with advanced disease cannot be offered a treatment that is completely effective. Surgical resection is the treatment of choice, but less than 20% of patients are candidates for this treatment. Hepatic cryosurgery is a relatively new procedure in which the tumor is localized intraoperatively with ultrasound guidance and exposed to liquid nitrogen at -196 degrees C. Nine cases have been performed in Hawaii, and we present the first four cases here. Of these cases, there were no mortalities and only one patient required blood transfusion. All patients currently are alive with up to 11-month follow-up. Long-term studies will be necessary to assess the effectiveness of this modality.

Transcriptional regulation of PS-IAA4/5 and PS-IAA6 early gene expression by indoleacetic acid and protein synthesis inhibitors in pea (Pisum sativum)

The transcription of two genes, PS-IAA4/5 and PS-IAA6, in pea is induced by indoleacetic acid (IAA) and protein synthesis inhibitors such as cycloheximide (CHX) and anisomycin (ANI). Induction by IAA is rapid, taking 5 and 7.5 minutes for PS-IAA4/5 and PS-IAA6, respectively, and is independent of IAA concentration and whether IAA has a free or esterified carboxyl group (ethyl-IAA). The rate of mRNA accumulation, however, is dependent on hormone concentration, and is greater with IAA than with ethyl-IAA. The turnover rates (t1/2) of the PS-IAA4/5 and PS-IAA6 mRNAs are 60 and 75 minutes, respectively, and are not affected by IAA. CHX or ANI induce the transcription of PS-IAA4/5 and PS-IAA6 more slowly than IAA (5 to 10 minutes for PS-IAA4/5 and 20 minutes for PS-IAA6). While protein synthesis inhibitors stabilize both mRNAs, the rapidity of induction by CHX and ANI cannot be accounted for solely by mRNA stabilization. The relationship between mRNA induction and protein synthesis inhibition does not obey Michaelis-Menten kinetics, but rather is best described by a hyperbolic curve, suggesting the release of transcriptional repression by the inhibition of protein synthesis. RNA expression experiments with transgenic tobacco seedlings or with transfected pea protoplasts using PS-IAA4/5 promoter GUS or CAT fusions reveal that CHX transcriptionally activates PS-IAA4/5 gene expression. Thus, protein synthesis inhibitors have a dual effect on PS-IAA4/5 and PS-IAA6. (1) They stabilize both mRNAs (possibly by a translational arrest-linked process or by preventing the synthesis of a labile nuclease(s)). (2) They activate transcription (possibly by preventing the synthesis or function of a repressor).

A salvage technique for continuous ambulatory peritoneal dialysis catheters with exit-site infections

Catheter infection is a major complication of continuous ambulatory peritoneal dialysis (CAPD) therapy for end-stage renal disease. Catheter exist-site infections were treated with a new surgical technique consisting of dissection and removal of the existing catheter in the subcutaneous layer, insertion of a catheter connector and new catheter piece, and creation of a new subcutaneous tunnel. The new surgery can be performed on an outpatient basis and allows for the continuation of CAPD, thereby avoiding the cost associated with inpatient admission and interim hemodialysis.

Monocyte chemoattractant protein-3, but not monocyte chemoattractant protein-2, is a functional ligand of the human monocyte chemoattractant protein-1 receptor

Monocyte chemoattractant protein (MCP)-2 and -3 are recently identified members of the Cys-Cys chemokine family and are highly homologous to MCP-1. MCP-1, MCP-2, and MCP-3 are potent chemoattractants for monocytes, basophils, and T lymphocytes. In this study, we have examined potential interactions of MCP-2 and MCP-3 with the recently cloned MCP-1 receptor. MCP-3, but not MCP-2, induced a robust and dose-dependent mobilization of intracellular calcium in HEK-293 cells that had been stably transfected with the MCP-1 receptor. The kinetics of these calcium transients were similar to those elicited by MCP-1. MCP-1 and MCP-3 induced potent inhibition of adenylyl cyclase (concentrations giving 50% inhibition = 48 pM and 67 pM, respectively). MCP-3 bound to HEK-293 cells stably expressing the MCP-1 receptor, but with approximately 35-fold lower affinity than MCP-1. MCP-1 desensitized transfected HEK-293 cells expressing the MCP-1 receptor to activation by MCP-3 in the calcium mobilization assay, but MCP-3 did not effectively desensitize these cells to MCP-1. We conclude that MCP-3, but not MCP-2, is a functional ligand for the MCP-1 receptor.

Monocyte chemoattractant protein-3, but not monocyte chemoattractant protein-2, is a functional ligand of the human monocyte chemoattractant protein-1 receptor

Monocyte chemoattractant protein (MCP)-2 and -3 are recently identified members of the Cys-Cys chemokine family and are highly homologous to MCP-1. MCP-1, MCP-2, and MCP-3 are potent chemoattractants for monocytes, basophils, and T lymphocytes. In this study, we have examined potential interactions of MCP-2 and MCP-3 with the recently cloned MCP-1 receptor. MCP-3, but not MCP-2, induced a robust and dose-dependent mobilization of intracellular calcium in HEK-293 cells that had been stably transfected with the MCP-1 receptor. The kinetics of these calcium transients were similar to those elicited by MCP-1. MCP-1 and MCP-3 induced potent inhibition of adenylyl cyclase (concentrations giving 50% inhibition = 48 pM and 67 pM, respectively). MCP-3 bound to HEK-293 cells stably expressing the MCP-1 receptor, but with approximately 35-fold lower affinity than MCP-1. MCP-1 desensitized transfected HEK-293 cells expressing the MCP-1 receptor to activation by MCP-3 in the calcium mobilization assay, but MCP-3 did not effectively desensitize these cells to MCP-1. We conclude that MCP-3, but not MCP-2, is a functional ligand for the MCP-1 receptor.

Two auxin-responsive domains interact positively to induce expression of the early indoleacetic acid-inducible gene PS-IAA4/5

The plant growth hormone indole-3-acetic acid (IAA) transcriptionally activates expression of several genes in plants. We have previously identified a 164-bp promoter region (-318 to -154) in the PS-IAA4/5 gene that confers IAA inducibility. Linker-scanning mutagenesis across the region has identified two positive domains: domain A (48 bp; -203 to -156) and domain B (44 bp; -299 to -256), responsible for transcriptional activation of PS-IAA4/5 by IAA. Domain A contains the highly conserved sequence 5'-TGTCCCAT-3' found among various IAA-inducible genes and behaves as the major auxin-responsive element. Domain B functions as an enhancer element which may also contain a less efficient auxin-responsive element. The two domains act cooperatively to stimulate transcription; however, tetramerization of domain A or B compensates for the loss of A or B function. The two domains can also mediate IAA-induced transcription from the heterologous cauliflower mosaic virus 35S promoter (-73 to +1). In vivo competition experiments with icosamers of domain A or B show that the domains interact specifically and with different affinities to low abundance, positive transcription factor(s). A model for transcriptional activation of PS-IAA4/5 by IAA is discussed.

Signal transduction and ligand specificity of the human monocyte chemoattractant protein-1 receptor in transfected embryonic kidney cells

We have examined the ligand specificity and signal transduction pathways of a recently cloned receptor for monocyte chemoattractant protein-1 (MCP-1). In human 293 cells stably transfected with the MCP-1 receptor, MCP-1 bound specifically with high affinity (Kd = 260 pM) and induced a rapid mobilization of calcium from intracellular stores. The closely related chemokines MIP-1 alpha, MIP-1 beta, RANTES, interleukin 8 (IL-8), and Gro-alpha were inactive at concentrations as high as 300 nM. Activation of the MCP-1 receptor potently inhibited adenylyl cyclase with an IC50 = 90 pM. Activation of the MIP-1 alpha/RANTES receptor also mediated inhibition of adenylyl cyclase activity but with a different pharmacological profile: MIP-1 alpha (110 pM, IC50), RANTES (140 pM), MIP-1 beta (10 nM), and MCP-1 (820 nM). Mobilization of intracellular calcium and inhibition of adenylyl cyclase were blocked by pertussis toxin, suggesting that the MCP-1 receptor coupled to G alpha i. These results demonstrate that the MCP-1 receptor binds and signals in response to picomolar concentrations of MCP-1 in a highly specific manner. Signaling was manifested as mobilization of intracellular calcium and inhibition of adenylyl cyclase and was mediated by a pertussis toxin-sensitive G-protein(s).

Transjugular intrahepatic portosystemic shunt (TIPS): treatment of esophageal variceal bleeding

Management of esophageal variceal bleeding continues to be a difficult problem for the practicing physician. TIPS is an interventional radiologic procedure that involves creating a channel within the liver between the portal vein and the systemic circulation using an expandable metallic stent. Ten patients underwent TIPS at St Francis Medical Center and the technical success rate was 100%. Complications have been minimal. One patient has died from progressive hepatic failure and carcinoma, and 1 patient underwent liver transplantation. The remaining 8 patients have a patent TIPS in place and have not rebled.

GMHC volunteers and the challenges and hopes for the second decade of AIDS

A documentation of the impact of AIDS on New York City during the first decade of the epidemic must highlight the extraordinary responses of the Gay Men's Health Crisis (GMHC) and other community-based organizations. Data collected from volunteers (n = 587) at the close of this decade are presented to address concerns about how successfully an organization such as GMHC will be able to confront the challenging future of the epidemic. Questionnaire data on demographics and prior AIDS experiences and responses to a GMHC Reasons for Volunteering Scale, developed for this study through exploratory and confirmatory factor analysis strategies, are brought to bear on questions about the (1) diversity of the volunteer community, (2) the extent to which volunteers are burdened by potentially debilitating AIDS-related experiences, and (3) the promise for the continued effective and inspirational functioning of GMHC suggested by volunteers' reasons for choosing to volunteer at this time. Volunteers, 62% of whom are gay men and 28% are heterosexual women, represent a wide age range but little diversity in race/ethnicity and educational background. They arrive at GMHC 8 years after its founding with a slight majority having had significant prior experience with HIV-related events. There are six basic kinds of reasons for their volunteering, in order of importance: Joining the AIDS Cause, Personal Growth, Social Contact, Helping the Gay Family, Coping with AIDS, and Career Enhancement.

Allogeneic and autologous bone marrow transplant experiences in Hawaii

Allogeneic bone marrow transplant (BMT) was first performed successfully at St. Francis Medical Center in 1978. Since that time, 91 BMTs have been performed for aplastic anemia, leukemia, lymphoma, and Stage II, III and IV breast cancers. This article will explain the methods, complications and results of BMT in Hawaii.

25 years of kidney transplantation in Hawaii

The first kidney transplant in Hawaii was performed in August 1969. In the following 25 years, more than 433 kidney transplants were performed. The most common etiology leading to transplantation was chronic glomerulonephritis. Patient and graft survivals after a kidney transplant have progressively improved, particularly after the introduction of cyclosporine in 1984. The overall one-year patient and graft survival rates now are 96% and 85%, respectively; these results exceed the national averages.

Identification of the auxin-responsive element, AuxRE, in the primary indoleacetic acid-inducible gene, PS-IAA4/5, of pea (Pisum sativum)

The plant hormone auxin transcriptionally activates early genes in pea. We have developed a transient assay system using protoplasts of auxin-responsive pea seedling cells to define the auxin-responsive element, AuxRE, of the early auxin-induced PS-IAA4/5 gene. The auxin responsive protoplasts show an authentic hormonal response identical to that observed in intact pea tissue, with respect to rapidity, specificity and cycloheximide (CHX) inducibility of the PS-IAA4/5 transcript. The hormone also mediates rapid and specific induction of chloramphenicol acetyltransferase (CAT) activity in protoplasts transfected with a chimeric IAA4/5-CAT gene. The IAA-induced CAT activity is developmentally regulated and is observed only in protoplasts derived from auxin-responsive regions of the pea seedling. Extensive deletion analysis of the PS-IAA4/5 promoter defined a promoter region between -318 and -154 that confers auxin inducibility. This AuxRE mediates auxin-inducible CAT activity in pea cells driven by the non auxin-responsive CaMV 35S minimal promoter. The functionality of this promoter region as an AuxRE was further verified in tobacco plants using IAA4/5-GUS gene fusions. The AuxRE contains two domains: Domain A acts as an auxin switch; domain B has an enhancer-like activity. The A and B domains contain the highly conserved sequences found in various auxin-regulated genes (T/GGT-CCCAT (domain A) and C/AACATGGNC/AA/GTGTT/CT/CC/A (domain B)). DNase I footprinting reveals binding of nuclear proteins to the highly conserved sequence found in A and B domains. The sequence of the A domain does not correspond to any known regulatory elements found in other eukaryotic genes, and the data suggest that this conserved motif functions as an AuxRE. A model for the early transcriptional activation of the PS-IAA4/5 gene by IAA is discussed.

Use of a tomato mutant constructed with reverse genetics to study fruit ripening, a complex developmental process

Fruit ripening is one of the most dramatic developmental transitions associated with extensive alteration in gene expression. The plant hormone ethylene is considered to be the causative ripening agent. Transgenic tomato plants were constructed expressing antisense or sense RNA to the key enzyme in the ethylene (C2H4) biosynthetic pathway, 1-aminocyclopropane-1-carboxylate (ACC) synthase using the constitutive CaMV 35S and fruit specific E8 promoters. Fruits expressing antisense LE-ACS2 RNA produce less ethylene and fail to ripen only when ethylene production is suppressed by more than 99% (> 0.1 nl/g fresh weight). Ethylene production is considerably inhibited (50%) in fruits expressing sense LE-ACS2 RNA. Antisense fruits accumulate normal levels of polygalacturonase (PG), ACC oxidase (pTOM13), E8, E17, J49, and phytoene desaturase (D2) mRNAs which were previously thought to be ethylene-inducible. E4 gene expression is inhibited in antisense fruits and its expression is not restored by treatment with exogenous propylene (C3H6). Antisense fruits accumulate PG mRNA, but it is not translated. Immunoblotting experiments indicate that the PG protein is not expressed in antisense fruits but its accumulation is restored by propylene (C3H6) treatment. The results suggest that at least two signal-transduction pathways are operating during tomato fruit ripening. The independent (developmental) pathway is responsible for the transcriptional activation of genes such as PG, ACC oxidase, E8, E17, D2, and J49. The ethylene-dependent pathway is responsible for the transcriptional and posttranscriptional regulation of genes involved in lycopene, aroma biosynthesis, and the translatability of developmentally regulated genes such as PG.