Cognition as a parameter in monitoring the effect of multiple sclerosis relapse treatment: A prospective controlled study

BACKGROUND

Cognitive evaluation was considered to be very important in the relapse period, on the basis of the presence of isolated cognitive attacks and the necessity of monitoring the patient both physically and cognitively.

MATERIALS AND METHODS

People with MS (pwMS) who were hospitalized during relapse were included in the study. All MS patients were evaluated by the neurologist with Expanded Disability Status Scale (EDSS), The 9 Hole Peg Test (9HPT) and the Timed 25-Foot Walk Test (T25-FWT). Additionally, all participants were examined cognitively with the Turkish version of the Brief International Cognitive Assessment for MS (BICAMS) battery. Also, schedules were indicated as during relapse before the treatment (pre-treatment) and the first month after relapse (1-month follow-up).

RESULTS

A total of 140 MS patients (mean age; 34.98±10.09, mean disease duration; 6.05±5.29 years) and 86 healthy controls (mean age; 36.94±10.83) were included to the present study. The mean EDSS scores in pre-treatment in MS patients was 2.74±1.14 and decreased significantly in the 1-month follow-up (1.74±1.24; p<0.001). The mean SDMT score was lower by 8.76 points in MS patients than in HCs) in pre-treatment and 7.66 points in 1-month follow-up (p<0.001). The mean SDMT scores of all participants increased with measurement time gradually (p<0.001).

CONCLUSION

In this study, it was detected which cognitive domains were affected after relapse treatment and cognitive changes in pwMS during relapse and remission periods compared to the healthy controls. All three BICAMS test scores significantly increased in one-month follow-up than the pre-treatment period. The results showed that CVLT-II and BVMT-R scores improved more in pwMS than in HCs, and also SDMT scores of pwMS showed a trend of increase, but was not a significant improvement.

Developing a Novel Platelet-Rich Plasma-Laden Bioadhesive Hydrogel Contact Lens for the Treatment of Ocular Surface Chemical Injuries

Permanent injury to corneal limbal stem cells after ocular surface chemical and thermal injuries is a major cause of corneal blindness. In this study, a PRP-laden GelMA hydrogel contact lens is manufactured which is aimed to support the limbal niche after ocular surface insults thereby preventing limbal stem cell failure. GelMA with varying platelet-rich plasma (PRP) concentrations (5%, 10%, and 20%) is photopolymerized using a visible light crosslinking system followed by characterizations of mechanical properties, growth factor release, enzymatic degradation, and in vitro cytotoxicity. The addition of 10% PRP into 10% GelMA hydrogel precursor solution results in the highest tensile and compressive modulus (38 and 110 kPa, respectively) and burst pressure (251±37.66 mmHg). Degradation time varies according to the concentration of the collagenase enzyme tested (0, 2.5, 5, and 40 µg/mL) and is most prolonged with 20% PRP. EGF and TGF-β release profiles suggest an initial burst release followed by sustained release, most consistent in the 10% PRP sample. Although cell viability decreases on day 1, rapid recovery is observed and is approximately 120% after day 21. PRP-laden GelMA in the form of a contact lens may be a promising biomaterial-based treatment approach for the maintenance of limbal epithelial stem cells after ocular surface insults.

Right ventricular adaptation and subclinical damage by echocardiography in heart transplantation recipients: insights from myocardial work index

Aim

Right ventricular (RV) dysfunction is an important cause of graft failure after heart transplantation (HTx) and a challenge for echocardiographic evaluation. We sought to evaluate the accuracy of the most novel echocardiographic tools for the assessment of RV remodelling and function in asymptomatic HTx recipients with and without rejection.

Methods

All patients underwent right heart catheterization with biopsy, cardiac magnetic resonance (CMR) and echocardiography in a row within the same day while fasting, irrespective of symptoms, as part of institutional follow up protocol dedicated to HTx recipients. Invasively measured systolic pulmonary artery pressure was used to calculate RV myocardial work index (MWI) from strain-pressure loops by using the custom software (EchoPAC BT204, Horten, Norway). Event timings were determined from pulmonic and tricuspid valve opening and closures. With the aim to generate full bull's eye map by automated function imaging, we computed RV LS data from the apical 4-chamber view 3 times, from 3 consecutive cycles substituting apical LV views. Other indices of RV function were measured according to the EACVI 2015 recommendations for chamber quantification. RV volumes and ejection fraction (EF) were quantified by CMR. Echocardiographic measurements were compared with CMR derived RV EF and biopsy findings as the reference for microstructural changes. We also evaluated by echocardiography organ donors as healthy controls.

Results

Sixty-one fully matching studies (echo, CMR, catheter, biopsy) were analyzed. Tricuspid systolic annular velocity (S'), peak systolic excursion (TAPSE) and longitudinal strain (LS) were significantly lower in healthy HTx recipients as compared to controls (p&lt;0.001 for all). Whereas, RV volumes, EF and fractional area change (FAC) were not different between HTx recipients and healthy controls (Figure 1, EDV:end-diastolic volume). In the overall HTx recipients, only FAC (r=0.51, p&lt;0.001) but not S', TAPSE, LS or MWI correlated with CMR derived EF. Biopsy defined subclinical rejections however were nicely mirrored by LS, and MWI (Figure 2), whereas other indices failed to reflect microstructural changes. In addition, MWI had higher accuracy than LS to discriminate biopsy findings. RV volumes, EF, FAC as well as TAPSE, S' were insensitive to subclinical myocardial damage.

Conclusion

RV adaptation in healthy HTx recipients is characterized by decreased longitudinal function but preserved overall RVFAC, EF, and volumes. MWI seems to be more reliable than other echocardiographic parameters to track subclinical RV myocardial damage due to rejection, while the RV EF remains preserved.

Funding Acknowledgement

Type of funding sources: None.

T1 mapping of the right ventricle in heart transplant recipients: how does it correlate with endomyocardial biopsy findings?

Aim

Noninvasive detection of cardiac allograft rejection is highly desirable. We sought to assess how right ventricular (RV) T1 mapping correlates with endomyocardial biopsy findings.

Methods

All patients underwent right heart catheterization with biopsy and cardiac magnetic resonance (CMR) irrespective of symptoms, as part of the institutional registry protocol dedicated to heart transplant (HTx) recipients. CMR studies were performed using a 1.5 T scanner and analyses by using a commercially available software (CMR42, Circle CVI, Calgary, Canada). Endocardial and epicardial borders were drawn on end-systolic and end-diastolic phases for ventricular function analysis. For T1 measurements, region of interests located at the RV free-wall were drawn manually on midventricular short-axis slices avoiding blood pool and epicardial fat. Extracellular volume (ECV) was calculated as ECV = (1 − hematocrit) × (ΔR1 myocardium/ΔR blood), where R1 = 1/T1. Late gadolinium enhancement (LGE) images were also obtained using a phase-sensitive inversion recovery segmented gradient echo sequence. Hyperenhancement was assessed semi-quantitatively as segmental (2–3 cm) or diffuse (&gt;3 cm). Allograft rejection was determined based on the severity of inflammatory infiltrates and myocyte damage on pathological specimens according to the standardized International Society for Heart and Lung Transplantation (ISHLT) nomenclature.

Results

In all, 61 paired studies were evaluated. None of the patients had heart failure symptoms. We defined 3 subgroups: Group I; never rejected (n=23), group II; biopsy remarkable for rejection (n=19) and group III; history of past rejection(s) (n=19). RV volumes and ejection fraction (EF) did not differ between the groups. However, rejections were nicely mirrored by T1 time and particularly by ECV. Of note, T1 time and ECV improved but not completely normalized after resolution of rejection. Overall, T1 time (cut off 1060ms) and ECV (cut off 35%) were sensitive (84%, both) and had high negative predictive values (88% and 87%, respectively) but not specific (43% and 52% respectively) for discriminating rejection related subclinical RV damage. Their specificity slightly improved to 52 and 61% respectively, if patients with previous rejection were excluded (Figure 1). LGE did not discriminate rejection.

Conclusion

RV volumes and EF are insensitive to detect allograft rejection. Native T1 time and ECV of the RV, as a means of extracellular expansion, likely reflect interstitial fibrosis, oedema, and inflammation that are typical for, but not limited to allograft rejection. Hence, these parameters can help to exclude rejection but have limited standalone value for making the nonivasive diagnosis due to their low specificity. These results cannot be extrapolated to the left ventricle.

Funding Acknowledgement

Type of funding sources: Private hospital(s). Main funding source(s): University of Baskent

A novel way of using pyrolytic gas derived from waste rubber: Pyrometallurgical reduction of NiO

In the present study, a novel way of using pyrolytic gas generated by the pyrolysis of waste rubber was introduced. The method involves reduction of metal oxides by pyrolytic gas. The pyrometallurgical reduction behavior of NiO was studied to demonstrate the feasibility of the process. The rubber pyrolysis and the NiO reduction experiments were carried out in a horizontal tube at 1000 K using Ar as carrier gas. It was determined that the waste rubber was completely pyrolyzed in Ar flow. The extent of NiO reduction was investigated as a function of mass ratio of rubber to NiO (0-7.345). X-ray diffraction and mass measurements revealed that single-phase Ni was obtained at the ratio of 0.734. Complete reduction of NiO to Ni was predicted at the lower mass ratios by thermodynamics. The quantitative discrepancy between the thermodynamics and the experiments was discussed. Thermodynamic analysis of the Ni-O-C-H-Ar system indicated that NiO was reduced to Ni by the gaseous species (essentially H₂, CH₄, C₆H₆) at 1000 K. The novel route presented here may be extended to the reduction of other materials using waste rubber.

Ultrasonographic evaluation of Achilles tendon in children with flatfoot: A case-control morphometric study

PURPOSE

The purpose of this study was to investigate whether any relationships exist between the presence of flatfoot and ultrasonographic morphometric findings of Achilles tendon in children.

MATERIALS AND METHODS

The study included 30 pediatric patients with a mean age of 11.96±2.44 (SD) years (range: 9-16 years) with flexible flatfoot and 29 healthy pediatric controls who were matched for age and served as a control group. Demographic data of both groups such as age, height and weight, and anthropometric measurements including leg length and, length and cross-sectional area of the Achilles tendon on ultrasonography were tabulated. Relationships between the cross-sectional area of Achilles tendon and flatfoot and the other parameters were searched for using backward multiple regression analysis.

RESULTS

No associations between flatfoot and length and cross-sectional area of the Achilles tendon, age, height, leg and foot length were found. A negative correlation was found between the cross-sectional area of Achilles tendon and presence of flatfoot (Beta=-4.93, P=0.01) and age (Beta=-1.96, P=0.04). A positive correlation was found between the cross-sectional area of Achilles tendon and shoe size (Beta=2.13, P=0.007).

CONCLUSIONS

Flatfoot, shoe size, age and weight must be kept in mind as a clue for a thinner Achilles tendon morphometry which can be a risk factor in lower limb pathologies.

Gene expressions of TRP channels in glioblastoma multiforme and relation with survival

Glioblastoma multiforme (GBM) is one of the most lethal forms of cancer in humans, with a median survival of 10 to 12 months. Glioblastoma is highly malignant since the cells are supported by a great number of blood vessels. Although new treatments have been developed by increasing knowledge of molecular nature of the disease, surgical operation remains the standard of care. The TRP (transient receptor potential) superfamily consists of cation-selective channels that have roles in sensory physiology such as thermo- and osmosensation and in several complex diseases such as cancer, cardiovascular, and neuronal diseases. The aim of this study was to investigate the expression levels of TRP channel genes in patients with glioblastoma multiforme and to evaluate the relationship between TRP gene expressions and survival of the patients. Thirty-three patients diagnosed with glioblastoma were enrolled to the study. The expression levels of 21 TRP genes were quantified by using qRT-PCR with dynamic array 48 × 48 chip (BioMark HD System, Fluidigm, South San Francisco, CA, USA). TRPC1, TRPC6, TRPM2, TRPM3, TRPM7, TRPM8, TRPV1, and TRPV2 were found significantly higher in glioblastoma patients. Moreover, there was a significant relationship between the overexpression of TRP genes and the survival of the patients. These results demonstrate for the first time that TRP channels contribute to the progression and survival of the glioblastoma patients.

Relationship between neutrophil-to-lymphocyte ratio and impaired myocardial perfusion in cardiac syndrome X

OBJECTIVE

Myocardial tissue perfusion is decreased in patients with cardiac syndrome X (CSX). Systemic inflammation appears to be an important contributor to the diseased microvascular network of these patients. The neutrophil-to-lymphocyte ratio (NLR) is a surrogate marker of inflammation. Accordingly, we evaluated this biomarker concerning the microvascular circulation of CSX patients.

PATIENTS AND METHODS

This study included 60 consecutive patients (54.1 ± 7.8 years of age, 49 females) with CSX (typical chest pain, positive exercise stress test results, and normal coronary angiograms) and 60 consecutive age- and sex-matched control subjects. In all coronary territories, epicardial coronary flow was assessed by the Thrombolysis In Myocardial Infarction frame count (TFC) method, and myocardial tissue perfusion was assessed by the myocardial blush grade (MBG) method. Normal myocardial perfusion was accepted as an MBG score of 3 in all coronary territories.

RESULTS

Patients with CSX had higher NLRs than those of control subjects (1.98 ± 0.77 vs 1.72 ± 0.55, respectively; p = 0.04). Among patients with CSX, those with impaired myocardial perfusion had higher NLRs than those with normal myocardial perfusion (2.13 ± 0.82 vs 1.71 ± 0.59, respectively; p = 0.028). There was a negative correlation between the NLR and total MBG score (p = 0.027, r = -0.29). Logistic regression analysis showed that the NLR was an independent and negative predictor of myocardial tissue perfusion (p = 0.027; Beta, -1.057; odds ratio, 2.878; 95% confidence interval, 1.129-7.335).

CONCLUSIONS

Patients with CSX have high NLRs, and inflammation seems to be associated with distorted myocardial perfusion in these patients.

Role of the transient receptor potential (TRP) channel gene expressions and TRP melastatin (TRPM) channel gene polymorphisms in obesity-related metabolic syndrome

OBJECTIVE

Metabolic syndrome (MetS) is correlated with increased cardiovascular risk and characterized by several factors, including visceral obesity, hypertension, dyslipidemia, and insulin resistance. The etiology of MetS is complex, and can be influenced by genetic susceptibility. The aim of this study was to investigate a possible association of transient receptor potential (TRP) channels gene expressions and TRP melastatin (TRPM) gene polymorphisms with MetS in a Turkish population.

PATIENTS AND METHODS

A total of 142 patients with obesity-related MetS and 166 healthy controls with similar age and sex were enrolled to this study. For polymorphism studies, genomic DNA from the participants was analyzed by a BioMark 96.96 dynamic array system (Fluidigm, South San Francisco, CA, USA). For gene expression studies, mRNA from blood samples was extracted, and real time polymerase chain reaction on the BioMark HD system was performed.

RESULTS

There was an increase in A allele (64.6% in patients vs. 49.5% in controls) and decrease in G allele frequencies (35.4% in patients vs. 50.5% in control, p = 0.0019) of the TRPM5 gene rs4929982 (Arg578Gln) polymorphism. We also observed that the distribution of genotype and allele frequencies of the TRPM8 gene rs12472151 in MetS patients were significantly different from controls (p < 0.0001). Although there were marked decreases in TRPC1, TRPC3, TRPM2, TRPM5, TRPV4, TRPV5, TRPV6, MCOLN2 (TRPML2), and MCOLN3 (TRPML3) gene expressions, an augmentation was noted in TRPC6 gene expression.

CONCLUSIONS

Genetic polymorphisms in TRPM5 and TRPM8 genes may modify individual susceptibility to MetS in the Turkish population. This study also revealed that there is a significant relationship between TRP channels gene expressions and MetS.

Association of Rho/Rho-kinase gene polymorphisms and expressions with obesity-related metabolic syndrome

OBJECTIVE

The metabolic syndrome (MetS) is a common multicomponent condition including abdominal obesity, dyslipidemia, hypertension and hyperglycemia. The aim of this study was to investigate the associations of Rho GTPase and Rho-kinase (ROCK) gene polymorphisms and expressions with MetS in a Turkish population.

PATIENTS AND METHODS

A total of 141 obese MetS patients and 163 healthy controls with similar age and sex were included to this study. Polymorphisms were analyzed in genomic DNA using a BioMark 96.96 dynamic array system. mRNA from blood samples was extracted, and real-time polymerase chain reaction was performed for gene expressions.

RESULTS

We observed that genotype (CC, 18.1%; CA, 13.4%, and AA, 68.5%) and allele (C, 24.8%; A, 75.2%) frequencies for the rs35996865 polymorphism of the ROCK1 gene in patients were markedly different from controls (CC, 84.2%; CA, 2.9%, and AA, 12.9%; C, 85.6%; A, 14.4%, p < 0.0001). In the rs2230774 (Thr431Asn) polymorphism of the ROCK2 gene, there were increases in the CC genotype (16.5%) and C allele frequencies (20.4%) in MetS patients when compared with the control group (CC, 6.0%, p = 0.0009, and C, 6.7%, p < 0.0001). However, no associations with the other 18 polymorphisms studied were found. Although there were an increase in peripheral blood mRNA RhoH expressions, marked decreases in RhoC, RhoBTB1, RhoV, Rnd1, and CDC42 gene expressions were noted in MetS patients.

CONCLUSIONS

This is the first study to provide evidence that ROCK gene polymorphisms and gene expressions of the Rho GTPase proteins may modify individual susceptibility to MetS in the Turkish population.

First Report of Group 16SrXII Phytoplasma Causing Stolbur Disease in Potato Plants in the Eastern and Southern Anatolia Regions of Turkey

In recent years, a stolbur-like disease has had devastating effects on the yield and marketable quality of potato production in Erzurum (Eastern Anatolia) and Akcakale-Sanliurfa (Southern Anatolia) regions of Turkey. Potato plants exhibited several different symptoms including stunting, upward rolling of the top leaves along with reddish or purplish coloration, chlorosis, shortened internodes, swollen nodes, proliferated axillary buds, aerial tubers, and early plant decline. An extensive survey from 2003 to 2010 was performed and diseased plant samples were collected. Total genomic DNAs were isolated from the leaf mid-veins of the six different symptomatic and two symptomless plants selected. Nested-PCRs, carried out by using phytoplasma-universal primer pair P1/P7 followed by R16F2n/R16R2 (2), amplified 16S rDNA fragments (F2nR2) from only templates derived from symptomatic plants. F2nR2 PCR products from two independent symptomatic plants were cloned and sequenced from both directions with M13 universal primers. The obtained 16S rDNA sequence (GenBank Accession No HM485579) was subjected to virtual restriction fragment length polymorphism (RFLP) analysis using iphyclassifier software (3). Results indicated that the phytoplasma, here identified in association with potato plants, shared best sequence identity (99%) with members of subgroup 16SrXII-A (e.g., GenBank Accession No. EU010006). Moreover, collective RFLP pattern of potato-associated phytoplasma differed from digestion profiles of previously described 16SrXII subgroups, sharing best similarity coefficient (0.94) with the reference phytoplasma strain of subgroup 16SrXII-A (GenBank Accession No. AJ964960). Thus, it was confirmed that potato-associated phytoplasma represents a new 16SrXII subgroup (16SrXII-N). Furthermore, a new primer set (PatsecF/PatsecR) was designed for priming specific PCR-amplification of potato-associated phytoplasma 16S rDNA sequence. PCR reaction was successfully used for specifically detecting stolbur phytoplasma in infected potato plants. The use of this method may help to determine possible alternative hosts and vectors of potato phytoplasma, which is important for development of an integrated management strategy for effective control of this disease in the future. Presence of potato stolbur diseases in the Eastern Anatolia Region of Turkey has previously been reported (1). To our knowledge, this is the first report of occurrence of a 16SrXII group phytoplasma causing potato stolbur diseases caused in the Eastern and Southern Anatolia regions of Turkey. References: (1) A. Citir. J. Turk. Phytopathol. 14:53, 1985. (2) D. E. Gundersen and I. M. Lee. Phytopathol. Mediterr. 35:144, 1996. (3)Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

Epicardial adipose tissue thickness by echocardiography is a marker for the presence and severity of coronary artery disease

BACKGROUND AND AIM

Epicardial adipose tissue (EAT), which is thought to be a component of visceral adiposity, is associated with the metabolic syndrome. We aimed to test the hypothesis that echocardiographic EAT thickness can be a marker for the presence and severity of coronary artery disease (CAD).

METHOD AND RESULTS

In all, 150 patients (100 patients with CAD and 50 patients with normal coronary arteries by diagnostic coronary angiography; 65 women, 85 men; mean age 55.7+/-7.4 years) were enrolled. EAT thickness was measured using 2-D echocardiographic parasternal long- and short-axis views. EAT thickness measurements were compared with angiographic findings. EAT thickness was significantly higher in patients with CAD in comparison to those with normal coronary arteries (6.9+/-1.5 mm vs. 4.4+/-0.8 mm; P<0.001). Furthermore, EAT thickness increased with the severity of CAD (multivessel disease 7.4+/-1.2 mm vs. single vessel disease 5.7+/-1.7 mm; P<0.001). Gensini's score significantly correlated with EAT thickness (r=0.600, P<0.001). EAT thickness of > or = 5.2 mm had 85% sensitivity and 81% specificity (ROC area 0.914, P<0.001, 95% CI [0.86-0.96]) for predicting CAD.

CONCLUSION

EAT thickness, which is easily and non-invasively evaluated by transthoracic echocardiography, can be an adjunctive marker to classical risk factors for the prediction of CAD.

Dynamics of chromosome compaction during mitosis

We have quantitatively studied the space-time dynamics of mitotic chromosome compaction in cultured amphibian cells. After collecting digital phase-contrast images we have done digital image analysis to study spatial correlations in density. We find a characteristic distance at which the strongest correlations occur, which provides a quantitative measure of the size of patches of dense chromatin during interphase and early prophase. Later in mitosis, this length corresponds to the thickness of prophase and metaphase chromosomes. We find that during interphase strong correlations exist at a few-micrometer length; during prophase this correlation length progressively drops as the chromosomes are compacted. Our data are explained by a model based on assembly of chromatin loops onto already fiberlike interphase chromosomes. To test this model we have microinjected cobalt hexamine trichloride into interphase nuclei and have observed the rapid condensation of the interphase chromatin into thick fibers with a spacing similar to the native-state interphase correlation length determined from our image analysis.

The bending rigidity of mitotic chromosomes

The bending rigidities of mitotic chromosomes isolated from cultured N. viridescens (newt) and Xenopus epithelial cells were measured by observing their spontaneous thermal bending fluctuations. When combined with simultaneous measurement of stretching elasticity, these measurements constrain models for higher order mitotic chromosome structure. We measured bending rigidities of B approximately 10(-22) N. m(2) for newt and approximately 10(-23) N. m(2) for Xenopus chromosomes extracted from cells. A similar bending rigidity was measured for newt chromosomes in vivo by observing bending fluctuations in metaphase-arrested cells. Following each bending rigidity measurement, a stretching (Young's) modulus of the same chromosome was measured in the range of 10(2) to 10(3) Pa for newt and Xenopus chromosomes. For each chromosome, these values of B and Y are consistent with those expected for a simple elastic rod, B approximately YR(4), where R is the chromosome cross-section radius. Our measurements rule out the possibility that chromosome stretching and bending elasticity are principally due to a stiff central core region and are instead indicative of an internal structure, which is essentially homogeneous in its connectivity across the chromosome cross-section.

Probing chromosome structure with dynamic force relaxation

We report measurements of the dynamics of force relaxation in single mitotic chromosomes, following step strains applied with micropipettes of force constant approximately 1 nN/microm. The force relaxes exponentially after an elongation (l/l(0)) to less than 3x native length, with a relaxation time approximately 2 sec. This relaxation time corresponds to an effective viscosity approximately 10(5) times that of water. We experimentally rule out solvent flow into the chromosome as the mechanism for the relaxation time. Instead, the relaxation can be explained in terms of the disentanglement dynamics of approximately 80 kb chromatin loop domains.

Reversible and irreversible unfolding of mitotic newt chromosomes by applied force

The force-extension behavior of individual mitotic newt chromosomes was studied, using micropipette surgery and manipulation, for elongations up to 80 times native length. After elongations up to five times, chromosomes return to their native length. In this regime chromosomes have linear elasticity, requiring approximately 1 nN of force to be stretched to two times native length. After more than five times stretching, chromosomes are permanently elongated, with force hysteresis during relaxation. If a chromosome is repeatedly stretched to approximately 10 times native length and relaxed, a series of hysteresis loops are obtained that converge to a single reversible elastic response. For further elongations, the linear dependence of force on extension terminates at a force "plateau" of approximately 15-20 nN, near 30 times extension. After >30 times extensions, the elastic moduli of chromosomes can be reduced by more than 20-fold, and they appear as "ghosts": swollen, elongated, and with reduced optical contrast under both phase and differential interference contrast imaging. Antibody labeling indicates that histone proteins are not being lost during even extreme extensions. Results are interpreted in terms of extension and failure of chromatin-tethering elements; the force data allow estimates of the number and size of such connectors in a chromosome.