Microtubule glycylation promotes attachment of basal bodies to the cell cortex.

Motile cilia generate directed hydrodynamic flow that is important for the motility of cells and extracellular fluids. To optimize directed hydrodynamic flow, motile cilia are organized and oriented into a polarized array. Basal bodies (BBs) nucleate and position motile cilia at the cell cortex. Cytoplasmic BB-associated microtubules are conserved structures that extend from BBs. By using the ciliate, Tetrahymena thermophila, combined with EM-tomography and light microscopy, we show that BB-appendage microtubules assemble coincidently with new BB assembly and that they are attached to the cell cortex. These BB-appendage microtubules are specifically marked by post translational modifications of tubulin, including glycylation. Mutations that prevent glycylation shorten BB-appendage microtubules and disrupt BB positioning and cortical attachment. Consistent with the attachment of BB-appendage microtubules to the cell cortex to position BBs, mutations that disrupt the cellular cortical cytoskeleton disrupt the cortical attachment and positioning of BBs. In summary, BB-appendage microtubules promote the organization of ciliary arrays through attachment to the cell cortex.

Kinesin-14 is Important for Chromosome Segregation During Mitosis and Meiosis in the Ciliate Tetrahymena thermophila.

Ciliates such as Tetrahymena thermophila have two distinct nuclei within one cell: the micronucleus that undergoes mitosis and meiosis and the macronucleus that undergoes amitosis, a type of nuclear division that does not involve a bipolar spindle, but still relies on intranuclear microtubules. Ciliates provide an opportunity for the discovery of factors that specifically contribute to chromosome segregation based on a bipolar spindle, by identification of factors that affect the micronuclear but not the macronuclear division. Kinesin-14 is a conserved minus-end directed microtubule motor that cross-links microtubules and contributes to the bipolar spindle sizing and organization. Here, we use homologous DNA recombination to knock out genes that encode kinesin-14 orthologues (KIN141, KIN142) in Tetrahymena. A loss of KIN141 led to severe defects in the chromosome segregation during both mitosis and meiosis but did not affect amitosis. A loss of KIN141 altered the shape of the meiotic spindle in a way consistent with the KIN141's contribution to the organization of the spindle poles. EGFP-tagged KIN141 preferentially accumulated at the spindle poles during the meiotic prophase and metaphase I. Thus, in ciliates, kinesin-14 is important for nuclear divisions that involve a bipolar spindle.

A rare case of spontaneous giant pneumorrachis presenting with cauda equina syndrome: a case report.

INTRODUCTION: Pneumorrachis is presence of air in the epidural space. It could be the result of trauma, barotrauma, iatrogenic or spontaneous. The pneumorrachis per se is an underdiagnosed entity as most of the patients are asymptomatic or have subclinical symptoms. The spontaneous occurrence of pneumorrachis has been reported in literature but giant spontaneous occurrence causing cauda equina syndrome has not been reported so far. CASE PRESENTATION: We report a case of 56-year-old male patient who came to our OPD on wheelchair with complains of difficulty in walking for 6 months with dribbling of urine for 2 months with on and off back pain. His perianal sensation was reduced with absent voluntary anal contraction. Imaging revealed giant air pockets in the spinal canal of L5-S1 extending upto L4-L5. It was managed surgically wherein laminectomy without fusion was done. The patient responded well to the treatment. DISCUSSION: There are many causes of pneumorrachis described in literature. Most of the cases of pneumorrachis are asymptomatic and incidentally diagnosed. With the improvement in radio-diagnostic modalities, the diagnosis of pneumorrachis can be easily established. When symptomatic, they can be managed conservatively. Those presenting with neurological deficit may require surgical intervention or other invasive intervention.

Single Sequence Whole-Spine Screening Magnetic Resonance Imaging: Diagnostic and Therapeutic Role in Multiple-Level Spinal Tuberculosis.

INTRODUCTION: Spinal tuberculosis (TB) is the most common form of skeletal tuberculosis. Paradiscal continuous vertebral involvement at a single level is the most prevalent pattern among all forms of spinal TB. There is a wide range of reported incidences of multiple-level non-contiguous spinal TB in the literature. We would like to discuss on the utility of single whole spine screening T2-weighted (T2W) mid-sagittal magnetic resonance imaging (MRI) film in diagnosing multiple-level spinal TB and therapeutic benefits it can provide. METHODS: We have done a retrospective review of the collected data of patients in Vardhman Mahavir Medical College and Safdarjung Hospital from August 2017 to October 2021 to find the incidence of multiple-level spinal TB and possible factors attributed to this specific disease pattern. All the patients who had been diagnosed of spinal TB either microbiologically or histopathologically or by a good clinical response to anti-tubercular treatment (ATT) and had a whole spine screening MRI film, were included. Patients of spinal TB who did not have a whole spine screening MRI were excluded from the study. Multiple-level spinal TB was diagnosed when lesions were identified in vertebral levels other than a typical paradiscal lesion, and additional lesions were separated from the primary disease by at least one normal spinal segment. RESULTS: Among the patients, 242 met the inclusion criteria, and 76 showed multiple-level non-contiguous spinal TB on MRI, incidence being 31.4%. The rest of the 166 patients showed typical single-segment contiguous lesions. By doing multivariate analysis to determine the independent risk factors for multiple-level spinal TB, extremes of age (<20 years and >50 years) have been found to be a significant factor with p value of 0.0001. Though drug resistance was not found to be a significant risk factor (p value 0.051), the proportion of patients having multiple-level TB was far more in the drug-resistant group (13/76). CONCLUSIONS: Single sequence whole spine screening MRI film is an effective, economical, and time-saving tool to detect multiple-level spinal TB. Along with its diagnostic accuracy, it also provides therapeutic benefits like access to a more approachable site for biopsy.

Hemorrhagic Ligamentum Flavum Cyst in the Adjacent Level of Lytic Spondylolisthesis - A Case of Diagnostic and Therapeutic Dilemma.

Introduction: Occurrence of hemorrhagic cyst inside ligamentum flavum is a very rare phenomenon and presents with back pain, radiculopathy, or neurogenic claudication. Various causes reported in the literature are trauma, anticoagulant therapy, and increased micromotion in the setting of unstable and degenerated motion segment. Case Report: We report a case of 41-year-old male patient who presented with claudication pain in both lower limbs for the past 6 months associated with bilateral calf atrophy. Plain radiograph with dynamic films showed lytic spondylolisthesis at L4-L5 level. Magnetic resonance imaging revealed a hemorrhagic cyst inside ligamentum flavum at the L3-L4 level occupying the posterior epidural space severely compressing the thecal sac. After a thorough diagnostic and therapeutic work up, we did a midline sparing decompression of L3-L4 level under microscope without fixing the listhetic segment. The patient had significant pain relief after surgery and doing well till now. Conclusion: In general, hemorrhagic cyst of ligamentum flavum is seen in a degenerated lumbar spine at the areas of increased micromotion and instability. Our case has shown that it can also occur in an adjacent segment of spondylolisthesis or instability. The obvious finding like listhesis in the adjacent segment may hinder a spine surgeon from diagnosing the cyst component and may guide to a erroneous treatment outline. Hence, it should not be missed in the imaging.

Spontaneous-Onset Delayed Spinal Arachnoiditis With Dorsal Cord Herniation in a 29-Year-Old Paraplegic Patient: A Case Report.

Spinal adhesive arachnoiditis is a rare occurrence with a diverse etiology. The clinical picture is not universal, and varying degrees of neurodeficit have been mentioned. Spontaneous spinal cord herniation or idiopathic spinal cord herniation occurs due to displacement of the cord through a dural or arachnoid defect. We report a case of a 29-year-old male paraplegic patient with a nontraumatic spinal cord injury (SCI) following surgery for an intradural extramedullary lesion at T10-T11 level who developed loss of truncal balance after two years of the index surgery. After a thorough clinical examination and MRI as well as other investigations, the patient was diagnosed as having spontaneous-onset delayed spinal arachnoiditis with dorsal cord herniation through the laminectomy window with effacement of neural tissue and ascending edema up to T6 level. A new-onset weakness or the development of an ascending loss of sensory level with a loss of truncal balance should alarm the therapist about some new pathology happening at the cord level in patients with SCI. In this regard, spinal adhesive arachnoiditis with or without cord herniation should always be suspected in a paraplegic patient with delayed-onset deterioration of neurology. Differential diagnoses like arachnoid web and arachnoid cysts should also be kept in mind.

Unilateral Neurological Deficit Due to Spinal Epidural Hematoma Following Midline-Sparing Spine Surgery: A Case Report.

Symptomatic spinal epidural hematoma (SEH) is a rare but well-documented complication in spine surgery, often associated with risk factors such as abnormal coagulation parameters, low platelets, excessive epidural bleeding, and inadequate hemostasis. While bilateral SEH is frequently described in the literature, unilateral SEH following spine surgery is seldom reported. We present a unique case of a unilateral neurological deficit resulting from an SEH following midline-sparing spine surgery due to unilateral drain placement in an 80-year-old male patient without comorbidities and normal coagulation parameters. Subsequent evacuation of the hematoma was done leading to gradual recovery of neurology. This emphasizes the importance of bilateral drain placement in such midline-sparing spine surgeries. This report underscores the significance of early SEH diagnosis and intervention, providing valuable insights into preventive measures and the need for a high index of suspicion in managing this potentially debilitating complication.

Clinico-Radio-Histopathological Correlation by C-Arm Image-Guided Biopsy in Spinal Tuberculosis.

BACKGROUND/PURPOSE OF THE STUDY: C-arm-guided biopsy is a safe and effective technique for evaluating TB spine and is useful in planning therapy. The purpose of this study was to find a correlation between clinically and radiologically suspected TB spine and C-arm image-guided biopsy-proven cases and to study the complications encountered. METHODS: After evaluating the clinical, laboratory, X-ray and MRI findings, 92 patients with provisionally diagnosed tubercular spine were subjected to C-arm image-guided biopsy. RESULTS: Among our 92 cases, histopathology was positive in 55 cases (59.78%). Out of these 55 histologically positive cases, CBNAAT was positive in 42 cases and negative in the rest 13 cases. Overall, among the 92 cases, CBNAAT was positive in 51(55.43%) of cases, and out of these, histopathology turned out to be positive in 42 of cases. Out of 41 cases with negative CBNAAT, histopathology was suggestive of tuberculosis in 13. The strength of agreement between CBNAAT and histopathology was statistically significant (p < 0.0001; kappa = 0.511). No complication such as bleeding, nerve/cord injury, infection, injury to aorta or pneumothorax was encountered during and after the C-arm biopsy in any case. CONCLUSION: C-arm image-guided biopsy is reasonably accurate and should be used as a tool for diagnosis of TB spine. We recommend histopathological examination as a key component for the diagnosis of TB spine, as it is precise and consumes relatively shorter time. CBNAAT is more rapid but is not a substitute for histopathology for spine TB diagnosis.

Two Antagonistic Hippo Signaling Circuits Set the Division Plane at the Medial Position in the Ciliate Tetrahymena.

In a single cell, ciliates maintain a complex pattern of cortical organelles that are arranged along the anteroposterior and circumferential axes. The underlying molecular mechanisms of intracellular pattern formation in ciliates are largely unknown. Ciliates divide by tandem duplication, a process that remodels the parental cell into two daughters aligned head-to-tail. In the elo1-1 mutant of Tetrahymena thermophila, the segmentation boundary/division plane forms too close to the posterior end of the parental cell, producing a large anterior and a small posterior daughter cell, respectively. We show that ELO1 encodes a Lats/NDR kinase that marks the posterior segment of the cell cortex, where the division plane does not form in the wild-type. Elo1 acts independently of CdaI, a Hippo/Mst kinase that marks the anterior half of the parental cell, and whose loss shifts the division plane anteriorly. We propose that, in Tetrahymena, two antagonistic Hippo circuits focus the segmentation boundary/division plane at the equatorial position, by excluding divisional morphogenesis from the cortical areas that are too close to cell ends.

Proteins that control the geometry of microtubules at the ends of cilia.

Cilia, essential motile and sensory organelles, have several compartments: the basal body, transition zone, and the middle and distal axoneme segments. The distal segment accommodates key functions, including cilium assembly and sensory activities. While the middle segment contains doublet microtubules (incomplete B-tubules fused to complete A-tubules), the distal segment contains only A-tubule extensions, and its existence requires coordination of microtubule length at the nanometer scale. We show that three conserved proteins, two of which are mutated in the ciliopathy Joubert syndrome, determine the geometry of the distal segment, by controlling the positions of specific microtubule ends. FAP256/CEP104 promotes A-tubule elongation. CHE-12/Crescerin and ARMC9 act as positive and negative regulators of B-tubule length, respectively. We show that defects in the distal segment dimensions are associated with motile and sensory deficiencies of cilia. Our observations suggest that abnormalities in distal segment organization cause a subset of Joubert syndrome cases.

Discovery and functional evaluation of ciliary proteins in Tetrahymena thermophila.

The ciliate Tetrahymena thermophila is an excellent model system for the discovery and functional studies of ciliary proteins. The power of the model is based on the ease with which cilia can be purified in large quantities for fractionation and proteomic identification, and the ability to knock out any gene by homologous DNA recombination. Here, we include methods used by our laboratories for isolation and fractionation of cilia, in vivo tagging and localization of ciliary proteins, and the evaluation of ciliary mutants.