Cytological Diagnosis of Primary Thyroid Tuberculosis

Primary thyroid tuberculosis is an extremely rare disease, even in countries where other forms of tuberculosis are abundant. TT has no age bar but usually affects women in fourth and fifth decade. Hereby, we report a case of 16-years-old girl presented with complaint of progressively increasing, painful thyroid swelling. Diagnosis of TT was made on cytology and there was no evidence of involvement of any other organ by tuberculosis. Despite of its rarity, TT is usually misdiagnosed. So, a clinician should always consider this entity in the differential diagnosis of thyroid swelling. Fine needle aspiration cytology is the best diagnostic method and can result in the avoidance of unnecessary thyroid surgeries.

Morphometric analysis and anatomical variations of infraorbital foramen: a study in adult North Indian population

PURPOSE

Various studies have been conducted on morphometric variations of infraorbital foramen to provide data to surgeons for nerve block in infraorbital region. This study aims to analyse the anatomical variations by comparing various morphometric measurements of infraorbital foramen in dry skulls of adult North Indian population. This study becomes relevant in the present study group as very scant data is available about the variations and morphometric measurements in Indian population. The data thus collected can be standardized and become useful for the surgeons working in this area of face.

MATERIALS AND METHODS

The study was conducted on 75 dry adult human skulls, which were a part of Department of Anatomy, used for teaching purposes in medical colleges. Straight distance of the Infraorbital foramen from the infraorbital rim, supraorbital foramen and sagittal plane was measured. The position of the infraorbital foramen was determined in relation to maxillary teeth and supraorbital foramen. The data thus obtained was analysed.

RESULTS

The distance of infraorbital foramen from infraorbital rim, supraorbital foramen, sagittal plane in the present study was found to be 6.71 ± 1.11 mm, 42.02 ± 4.31 mm and 31.94 ± 4.88 mm respectively. The position of infraorbital foramen was lateral in relation to supraorbital foramen (in 88% of cases). Infraorbital foramen was above the 1st premolar tooth in most of the cases. Accessory infraorbital foramen was found in 11.2% cases (double foramen).

CONCLUSION

The data thus obtained will perhaps be helpful to the surgeons in identifying the extent of the operative field thereby reducing procedural risks.

A case of lung mass: a common association between uncommon diseases

A young man presented with a history of cough, chest pain and streaky haemoptysis with low-grade fever. Further evaluation revealed a mass in the left hemithorax, which was biopsied to reveal cryptococcoma. The patient was HIV negative. Flow cytometry lymphocyte subset analysis showed reduced CD4+ T lymphocytes. Absolute CD4+ lymphocyte count was only 230 (normal range 530-1300). The patient was started on injectable amphotericin B, which was given for 1 month, and he was discharged on oral fluconazole.

Giant mediastinal haemangiopericytoma: an uncommon case

Haemangiopericytoma is a rare soft tissue tumour characterised by tightly packed tumour cells situated around thin walled endothelial lined vascular channels, ranging from capillary sized vessels to large gaping sinusoidal spaces. The tumour cells are surrounded by reticulin and are negative for muscle, nerve and epithelial markers. The diagnosis of extra-pulmonary intra-thoracic, extra-pleural mediastinal mass is difficult. It constitutes only 6% of all primary tumours and cysts of the mediastinum. We report the rare occurrence of primary intra-thoracic, extra-pulmonary mediastinal haemangiopericytoma of mesenchymal origin with perivascular localisation. The patient underwent right postero-lateral thoracotomy and post-operatively received chemotherapy with adriamycin (60 mg/m2) on day 1 and ifosfamide (1.5 g/m2) on day 1 to 3. Thirty-seven months after the operation, the patient has been well with evidence of a single recurrence in the left lower lobe.

Electrophysiological responses to emotional prosody perception in cochlear implant users

The present electroencephalographic (EEG) study investigated the ability of cochlear implant (CI) users to recognize emotional prosody. Two CI speech-processing strategies were compared: the ACE (Advance Combination Encoder) and the newly developed MP3000. Semantically neutral sentences spoken in three different emotional prosodies (neutral, angry, happy) were presented to 20 post-lingually deafened CI users and age-matched normal-hearing controls. Event related potentials (ERPs) were recorded to study the N100 and the P200 responses. In addition, event-related spectral power modulations were calculated to study the brain activity corresponding to the recognition of prosody in earlier (0–400) as well as later (600–1200) part of the stimuli where the prosodic features differed maximally. CI users with MP3000 strategy showed a higher proportion of correctly recognized prosodic information compared to the ACE strategy users. Our ERP results demonstrated that emotional prosody elicited significant N100 and P200 peaks. Furthermore, the P200 amplitude in response to happy prosodic information was significantly more positive for the MP3000 strategy compared to the ACE strategy. On spectral power analysis, two typical gamma activities were observed in the MP3000 users only: (1) an early gamma activity in the 100–250 ms time window reflecting bottom–up attention regulation; and (2) a late gamma activity between 900 and 1100 ms post-stimulus onset, probably reflecting top–down cognitive control. Our study suggests that the MP3000 strategy is better than ACE in regard to happy prosody perception. Furthermore, we show that EEG is a useful tool that, in combination with behavioral analysis, can reveal differences between two CI processing strategies for coding of prosody-specific features of language.

Regular in situ simulation training of paediatric medical emergency team improves hospital response to deteriorating patients

AIM OF THE STUDY

The introduction of a paediatric medical emergency team (pMET) was accompanied by integration of weekly in situ simulation team training into routine clinical practice. On a rotational basis, all key ward staff participated in team training, which focused on recognition of the deteriorating child, teamwork and early consultant review of patients with evolving critical illness. This study aimed to evaluate the impact of regular team training on the hospital response to deteriorating in-patients and subsequent patient outcome.

METHODS

Prospective cohort study of all deteriorating in-patients of a tertiary paediatric hospital requiring admission to paediatric intensive care (PICU) the year before, and after, the introduction of pMET and concurrent team training.

RESULTS

Deteriorating patients were: recognised more promptly (before/after pMET: median time 4/1.5 h, p<0.001), more often reviewed by consultants (45%/76%, p=0.004), more often transferred to high dependency care (18%/37%, p=0.021) and more rapidly escalated to intensive care (median time 10.5/5 h, p=0.024). These improved responses by ward staff extended beyond direct involvement of pMET. There was a trend towards fewer PICU admissions, reduced level of sickness at the time of PICU admission, reduced length of PICU stay and reduced PICU mortality. Introduction of pMET coincided with significantly reduced hospital mortality (p<0.001).

CONCLUSIONS

These results indicate that lessons learnt by ward staff during regular in situ team training led to significantly improved recognition and management of deteriorating in-patients with evolving critical illness. Integration of in situ simulation team training in clinical care has potential applications beyond paediatrics.

Increasing incidence of fluoroquinolone-resistant Mycobacterium tuberculosis in Mumbai, India

SETTING

Tertiary referral centre, private hospital, Mumbai, India.

OBJECTIVE

To analyse the incidence of fluoroquinolone (FQ) resistant Mycobacterium tuberculosis (TB) in our laboratory from 1995 to 2004.

DESIGN

Retrospective review and analysis of the drug susceptibility test records of all M. tuberculosis culture-positive samples from our Microbiology Department from 1995 to 2004.

RESULTS

FQ resistance has increased exponentially in our laboratory, from 3% in 1996 to 35% in 2004. The incidence of multidrug-resistant tuberculosis has also increased during the same period, from 33% in 1995 to 56% in 2004.

CONCLUSION

The incidence of FQ-resistant M. tuberculosis is gradually increasing to alarming levels. This may be due to widespread use of this vital group of drugs in the treatment of community-acquired infections. We urge that these broad spectrum antibiotics be used judiciously, and ideally be reserved for treatment of resistant TB in TB-endemic areas.

Spiral enteroscopy with the new DSB overtube: a novel technique for deep peroral small-bowel intubation

BACKGROUND AND STUDY AIMS

Spiral enteroscopy is a new technique for deep small-bowel intubation that uses a special overtube (Discovery Small Bowel, DSB) to pleat small bowel. The aims of this prospective study were to evaluate the use of a new-design DSB over new, longer and smaller-diameter enteroscopes, the Fujinon EN-450T5 and the Olympus SIF-Q180.

PATIENTS AND METHODS

This is a prospective study of 75 patients at two referral centers. All enteroscopies were performed by two experienced endoscopists. Patients underwent spiral enteroscopy perorally with the DSB and either the Fujinon EN-450T5 or the Olympus SIF-Q180 enteroscope. Procedure time and depth of insertion past the ligament of Treitz were determined for all patients.

RESULTS

Peroral spiral enteroscopy with DSB was performed in 50 patients with the Fujinon enteroscope and in 25 patients with the Olympus. Average estimated depth of insertion was 243 cm (range 50 - 380 cm) vs. 256 cm (range 50 - 400 cm) and the average time to reach this depth was 18.7 minutes (range 7 - 52 minutes) vs. 16.2 minutes (range 7 - 33 minutes) in the Fujinon and the Olympus groups respectively. Overall findings were 10 angiodysplasias, 2 small-bowel tumors, 1 Peutz-Jeghers polyp, 1 case of celiac sprue, 2 of small-bowel strongyloidiasis, and 2 small-bowel ulcers. All angiodysplasias were treated with bipolar cauterization. Biopsies were taken from the small-bowel tumors. There were no major complications.

CONCLUSIONS

The new DSB is a means of rapid, safe, and effective deep small-bowel intubation. Depth of insertion into the small bowel and total procedure time compare favorably with other deep enteroscopy techniques. The DSB performed equally well with both enteroscopes.

Subclinical peripheral neuropathy in stable middle-aged patients with chronic obstructive pulmonary disease

INTRODUCTION

Presently, there are few studies addressing the subject of peripheral neuropathy in patients with chronic obstructive pulmonary disease (COPD). Consequently, there is a dearth of evidence and awareness of subclinical neuropathy in stable COPD patients with no significant hypoxaemia, particularly in the age group of 40-60 years. The present study was designed to evaluate the subclinical peripheral neuropathy in this study group.

METHODS

60 subjects were included in the study. The COPD group comprised 30 male smokers with stable COPD, aged between 40 and 60 years and with no clinical neuropathy; and 30 age-matched healthy male volunteers served as the control group. The following nerves were evaluated for latency, amplitude and conduction velocity: for motor nerve conduction - median nerve, ulnar nerve, and common peroneal nerves; and for sensory nerve conduction - median nerve, ulnar nerve, and sural nerves.

RESULTS

Five out of 30 COPD patients had peripheral nerve impairment on electrophysiological evaluation. In these patients, we found decreased amplitude and conduction velocity in all examined sensory nerves; however, the conduction velocity was found to be more than 70 percent of the predicted value. These findings were suggestive of predominantly sensory (with milder involvement of motor nerves) axonal polyneuropathy.

CONCLUSION

We observed five out of 30 COPD patients to have predominantly sensory axonal peripheral neuropathy. These five COPD patients had significantly higher consumption of cigarettes, longer duration of illness and advanced airflow obstruction when compared to COPD patients with no peripheral neuropathy.

Pathogenesis and clinical approach to extraintestinal manifestations of inflammatory bowel disease

Crohn's disease (CD) and ulcerative colitis (UC), both should be considered as systemic diseases as they are associated with clinical manifestations involving the organs outside the alimentary tract. In a genetically susceptible host with inflammatory bowel disease (IBD), complex interaction of bacterial or other local factors in the colon with antigen presenting cells may trigger an immune reaction to a shared antigen in the involved organs. These extraintestinal manifestations (EIM) are observed in up to 20-40% of the patients with IBD. Patients with CD are more susceptible to EIMs than patients with UC. Joints, eyes, skin and biliary tract are the most commonly involved organ systems. Some manifestations such as uveitis, episcleritis may precede the onset bowel disease and some may occur in conjunction with or subsequent to the diagnosis of active bowel disease. Although many EIMs tend to follow the clinical course of IBD and respond to the treatment of underlying bowel disease, some EIMs such as primary sclerosing cholangitis and ankylosing spondylitis tend to follow a course independent of the bowel disease activity. Biological agents, particularly anti-TNFa based therapies now assume an important role in the treatment of EIMs. Early recognition and treatment of EIMs are crucial in preventing major morbidity.

Uncommon parathyroid mediastinal cyst compressing the trachea

Mediastinal parathyroid cyst is a rare cause of space occupying lesion in the mediastinum. No specific symptomatology may be attributed to the non-functioning parathyroid cyst. The diagnosis is rarely made before exploration. The cysts are thin walled, smooth, of varying sizes and contained clear, opalescent or haemorrhagic fluid. Histopathological examination reveals clusters of parathyroid cells dispersed in the wall of the cyst. Surgical removal is the treatment of choice and can be performed with minimal morbidity.

Pulmonary hyalinizing granuloma with ureteric fibrosis: A case report and review of relevant literature

A 52-year-old, asymptomatic patient presented with bilateral lung nodules on chest radiograph. She was diagnosed to have "pulmonary hyalinizing granuloma" on an open lung biopsy. We review the clinical features of this rare disease.

Anterior encephaloceles: a series of 103 cases over 32 years

Anterior encephalocele is a rarely reported CNS malformation with a geographical predilection for South-East Asia. The paucity of literature prompted us to analyse our results with hemiorbital advancement and classical Tessier's operation in 103 cases over 32 years (1971-2002). In our series, the frontoethmoidal subtype was the most common (80%), followed by the orbital (8%), transethmoidal (8%), transsellar (3%) and interfrontal types (1%). All patients with classical frontoethmoidal encephalocele had swelling over the nose or inner canthus since birth, with varying degrees of hypertelorism; and those with the nasopharyngeal subtype commonly presented with nasal obstruction and cerebrospinal fluid (CSF) rhinorrhoea. Neurofibromatosis was present in seven patients, all of whom had an orbital encephalocele. The diagnostic workup included a computerised tomography scan of the head in 96 patients and magnetic resonance imaging of the brain in 16 patients. The associated findings on imaging were hydrocephalus (15%), corpus callosum agenesis (7%), arachnoid cyst (3%), porencephalic cyst (3%) and single ventricle (3%). A classical Tessier's operation was performed in the initial 30 cases. However, since 1988, we have been performing a single stage hemiorbital advancement and repair of the encephalocele. There were three deaths, one due to pneumonia and two due to fulminant meningitis. Twenty-two patients (22%) had postoperative CSF leak, of which five required lumboperitoneal shunt placement. We believe that hemiorbital advancement offers satisfactory results with less morbidity than the Tessier's operation.

Technetium Tc-99m ethyl cysteinate dimer brain single-photon emission CT in mild traumatic brain injury: a prospective study

PURPOSE

To explore the role of single-photon emission CT (SPECT) in initial diagnostic evaluation of patients with mild traumatic brain injury (MTBI) and to identify subgroups in which it may serve as a useful diagnostic tool.

MATERIALS AND METHODS

Patients with MTBI seen during a 14-month period were prospectively included in this study. All patients had a CT of head within 12 hours of injury and SPECT by using technetium Tc99m ethyl cysteinate dimer (Tc99m-ECD) within 72 hours of injury. Both SPECT and CT findings were compared with clinical features such as posttraumatic amnesia (PTA), postconcussion syndrome (PCS), and loss of consciousness (LOC).

RESULTS

Ninety-two patients with MTBI underwent SPECT in the study period. There were 28 children and 64 adults, with male-to-female ratio of 4.5 to 1. CT findings were abnormal in 31 (34%) and SPECT in 58 (63%). The most common abnormality was hypoperfusion in the frontal lobe(s) in adults and the temporal lobe in children. A significantly higher number of perfusion abnormalities were seen in patients with PTA (P = .03), LOC (P = .02), and PCS (P = .01) than in patients without these symptoms. Compared to CT, SPECT had a much higher sensitivity for detecting an organic basis in these subgroup, of patients (P < .05).

CONCLUSION

Tc99m-ECD SPECT can be used as a complementary technique to CT in initial evaluation of patients with MTBI. It is particularly useful in patients having PCS, LOC, or PTA with normal CT scan.

Fusiform aneurysm of a persistent trigeminal artery

OBJECTIVE

Fusiform aneurysms of the persistent trigeminal artery are rare and endovascular treatment of these aneurysms has not been attempted previously. We describe a case of persistent trigeminal artery with a fusiform aneurysm in its middle third, managed using Guglielmi detachable coils (GDC).

CLINICAL PRESENTATION

A 50-year-old, diabetic and hypertensive patient presented with sudden onset headache and neck stiffness. On examination, she was conscious but disoriented, without cranial nerve or sensorimotor deficits. Four-vessel cerebral digital subtraction angiography revealed a fusiform aneurysm of the middle third of a persistent trigeminal artery on the left side with adult type posterior cerebral arteries.

INTERVENTION

Guglielmi detachable coils were used for occlusion of the persistent trigeminal artery.

RESULTS

The procedure was well tolerated but delayed ischemic neurological deficits developed due to vasospasm.

CONCLUSIONS

(1) In spite of angiographically documented independence of the anterior and posterior cerebral circulation, occlusion of a persistent trigeminal artery using endovascular techniques may result in posterior circulation stroke due to a number of factors, including occlusion of brainstem perforators taking origin from the persistent trigeminal artery or vasospasm. (2) The timing for endovascular intervention following aneurysmal rupture remains poorly defined.

Efficacy and results of expansive laminoplasty in patients with severe cervical myelopathy due to cervical canal stenosis

AIMS AND OBJECTIVES

To assess the efficacy and results of expansive laminoplasty in advanced (Nurick's Grade III or greater) cervical myelopathy.

MATERIALS AND METHODS

We reviewed data in 24 patients who underwent cervical laminoplasty from January 1999 to December 2002. Nuricks grading was used for quantifying the neurological deficits and outcome analysis was done using Odom's criteria. A modified Hirabayashi's open door laminoplasty was done using Titanium miniplates and screws in 22 patients, autologous bone in one and hydroxyapatite spacer in one patient.

OBSERVATIONS

There were 3 females and 21 males with a mean age of 56 years (range 39-72 years). Four patients presented in Nuricks Grade III, 15 in Grade IV and five in Grade V. MR imaging showed MSCS in 21 cases, OPLL in nine cases and ligamentum flavum hypertrophy in nine cases with cord signal changes being present in 19 cases.

RESULTS

All patients with duration of symptoms less than three years, and 50 % with duration ranging from three to six years had improvement by at least one Nurick's grade following surgery. Eighty-seven per cent Grade IV patients (ambulatory with support) improved to Grade III (ambulatory without support) following laminoplasty. Using Odom's criteria, 23 patients (95.8%) had a good to fair outcome.

CONCLUSIONS

Cord decompression with expansive laminoplasty using titanium miniplate fixation may improve the neurological outcome even in patients presenting late, and improvement by even one grade may have major 'quality of life' benefits for these patients.

Immunogenicity of a recombinant human immunodeficiency virus (HIV)-canarypox vaccine in HIV-seronegative Ugandan volunteers: results of the HIV Network for Prevention Trials 007 Vaccine Study

In the first preventative human immunodeficiency virus (HIV) vaccine study to be carried out in Africa, 40 HIV-seronegative Ugandan volunteers were randomly assigned to receive a canarypox vector containing HIV-1 clade B (env and gag-pro) antigens (ALVAC-HIV; n = 20), control vector containing the rabies virus glycoprotein G gene (n = 10), or saline placebo (n = 10). Cytotoxic T lymphocyte activity against target cells expressing clade A, B, and D antigens was assessed using standard chromium-release and confirmatory interferon-gamma enzyme-linked immunospot (ELISPOT) assays. Neutralizing antibody responses to cell line-adapted strains and primary isolates in all 3 clades were also tested. Twenty percent of vaccine recipients generated detectable cytolytic responses to either Gag or Env, and 45% had vaccine-induced HIV-specific CD8(+) T cell responses, as measured by the ELISPOT assay. In contrast, only 5% of the control group had vaccine-specific responses. Neutralizing antibodies against primary and laboratory-adapted HIV-1 clade B strains were seen in 10% and 15% of vaccine recipients, respectively, but responses against clades A and D were not detected. Although the immunogenicity of this clade B-based vaccine was low, ALVAC-HIV elicited CD8(+) T cell responses with detectable cross-activity against clade A and D antigens in a significant proportion of vaccine recipients.

Evaluation of antigen-specific responses using in vitro enriched T cells

Antigen-specific lymphocytes are important in the immune response to viral infection. Peripheral blood mononuclear cells (PBMC) are traditionally used as a source of effector cells in most immunological studies. We described here the use of the bispecific monoclonal antibodies (BSMAB) anti CD3:CD8 (CD3,8) and anti CD3:CD4 (CD3,4B) to expand and selectively enrich CD4+ and CD8+ T cells populations, respectively. The expanded cells demonstrated >90% CD3+CD4+ or CD3+CD8+ by 14 days. We measured HIV- and CMV-specific responses of these subset-enriched T cell and found that sensitivity and specificity is similar or higher when compared to PBMC in various cellular immunology assays (CMI). Vbeta analysis of BSMAB-enriched cells demonstrated comparable repertoire to the parent PBMC. Although both CD45RA(hi) and CD45RO(hi) cell populations were expanded with the BSMAB, selective subset depletion demonstrated that the antigen-specific T cell responses were restricted to the initial CD45RO(hi) memory effector subgroup. In conclusion, BSMAB in vitro enrichment of T cells allows significant expansion of the cell population without loss of specificity. This technique of cell expansion permits studies of T cell subset function in situations where the initial cell source is scarce, and presents an alternative for viable and functional T cells in immunological assays.

Spontaneous subdural hematoma in a young adult with hemophilia

We report a case of spontaneous acute subdural hematoma in a 30-year-old man, who was diagnosed with hemophilia during his hospital stay. He developed an extradural hematoma following evacuation of the acute SDH, which was also evacuated. He had a good outcome. Management of such a patient is discussed.

Pure red cell aplasia associated with thymoma

A case of thymoma with mixed spindle and lymphocytic variety along with acquired, secondary, chronic pure red cell aplasia is an uncommon entity. The presented case is a case of anterior mediastinal tumour with marked anemia. On histopathologic and hematological examinations, it proved to be a case of thymoma along with pure red cell aplasia. High index of suspicion, bone marrow examination, radiological including CT scan examination, total thymectomy after preparation with repeated blood transfusion remains the mainstay of treatment. Prolonged corticosteroid therapy leads to remission for upto ten months after operative intervention.

p27Kip1 regulates T cell proliferation

Our studies addressed the mechanism by which serum acts in conjunction with T cell receptor (TCR) agonists to promote the proliferation of primary splenic T cells. When added to resting splenocytes, TCR agonists initiated G(0)/G(1) traverse and activated cyclin D3-cdk6 complexes in a serum-independent manner. On the other hand, both TCR agonists and 10% serum were required for the activation of cyclin E-cdk2 and cyclin A-cdk2 complexes and the entry of cells into S phase. Serum facilitated cdk2 activation by maximizing the extent and extending the duration of the TCR-initiated down-regulation of the cdk2 inhibitor, p27(Kip1). Although p27(Kip1) levels were reduced (albeit submaximally) in cells stimulated in serum-deficient medium, nearly all of the cdk2 complexes in these cells contained p27(Kip1). In contrast, in cells receiving TCR agonist and 10% serum, little if any p27(Kip1) was present in cyclin-cdk2 complexes. Unlike wild-type splenocytes, p27(Kip1)-null splenocytes did not require serum for cdk2 activation or S phase entry whereas loss of the related cdk2 inhibitor, p21(Cip1), did not override the serum dependence of these responses. We also found that cdk2 activation was both necessary and sufficient for maximal expression of cdk2 protein. These studies provide a mechanistic basis for the serum dependence of T cell mitogenesis.

Analysis of cyclin D3-cdk4 complexes in fibroblasts expressing and lacking p27(kip1) and p21(cip1)

Our studies examined the effects of p27(kip1) and p21(cip1) on the assembly and activity of cyclin D3-cdk4 complexes and determined the composition of the cyclin D3 pool in cells containing and lacking these cyclin-dependent kinase inhibitors. We found that catalytically active cyclin D3-cdk4 complexes were present in fibroblasts derived from p27(kip1)-p21(cip1)-null mice and that immunodepletion of extracts of wild-type cells with antibody to p27(kip1) and/or p21(cip1) removed cyclin D3 protein but not cyclin D3-associated activity. Similar results were observed in experiments assaying cyclin D1-cdk4 activity. Data obtained using mixed cell extracts demonstrated that p27(kip1) interacted with cyclin D3-cdk4 complexes in vitro and that this interaction was paralleled by a loss of cyclin D3-cdk4 activity. In p27(kip1)-p21(cip1)-deficient cells, the cyclin D3 pool consisted primarily of cyclin D3 monomers, whereas in wild-type cells, the majority of cyclin D3 molecules were complexed to cdk4 and either p27(kip1) or p21(cip1) or were monomeric. We conclude that neither p27(kip1) nor p21(cip1) is required for the formation of cyclin D3-cdk4 complexes and that cyclin D3-cdk4 complexes containing p27(kip1) or p21(cip1) are inactive. We suggest that only a minor portion of the total cyclin D3 pool accounts for all of the cyclin D3-cdk4 activity in the cell regardless of whether the cell contains p27(kip1) and p21(cip1).

Primary keratinocytes have an adhesion dependent S phase checkpoint that is absent in immortalized cell lines

In order to understand the mechanism through which loss of anchorage inhibits growth, we have investigated the events that occur in murine keratinocytes upon substratum detachment utilizing both primary cells and established immortalized cell lines. Our data has revealed that while both primary and immortalized cells undergo growth arrest in suspension, the nature of this arrest is markedly different. Primary cells exhibit a growth arrest that is characterized by rapid cessation of DNA synthesis resulting in a static S phase population. In contrast, an immortalized non-tumorgenic cell line, Balb MK, exhibits growth arrest as measured by thymidine incorporation, but does not prevent cells that have entered S phase from continuing into G2/M, and accumulating as a 4N population. In contrast to both primary and MK cells, the tumorigenic SLC-1 cell line did not accumulate in a specific cell cycle interval and were able to undergo continuous growth in suspension. Examination of cyclin A protein and its associated activity revealed that cyclin A protein levels decreased in primary but not MK cells; suggesting the continued presence of cyclin A may allow continued DNA synthesis observed in MK cells. Furthermore, we demonstrate the accumulation of suspension cultured MK cells as a 4N population correlated with the loss of cyclin A/cdk2 kinase activity, which in turn occurred through the accumulation of p27kip1, whereas neither p27kip1 accumulation nor loss of cyclin A activity was observed in SLC-1 cells. Our results clearly reveal that the process of growth inhibition in suspension cultured cells may occur in several forms with distinct characteristics that are dependent on the status of cyclin/cdk complexes and CKI proteins. Tumor derived cells in suspension did not lose cyclin A dependent kinase activity and thus continued to grow and divide.