Hyperchrome

Macrocytic or magaloblastic anemia is caused by disturbances of DNA synthesis. It occurs, for example, in both folic acid and vitamin B12 deficiencies. Hematopoesis is slowed down due to reduced DNA synthesis and a reduced number of abnormally large (macrocytic) and hemaglobin-rich (hyperchromic) erythrocytes is released. 

The double-stranded structure of DNA can be separated into two component strands (melted) in solution by increasing the temperature or decreasing the salt concentration. Not only do the two stacks of bases puU apart but the bases themselves unstack while still connected in the polymer by the phosphodiester backbone. Concomitant with this denaturation of the DNA molecule is an increase in the optical absorbance of the purine and pyrimidine bases—a phenomenon referred to as hyperchromicity of denaturation. Because of the... 

Nucleic acids undergo heUx-to-coil transition with increasing temperature. The transition temperature Tm is defined as the temperature corresponding to which the hyperchromicity, H (absorbance at any temperature/absorbance at room temperature) is given by ... 

The UV-Vis spectra of the noncoordinated 5-amino-37/-l,3,4-thiadiazole-2-thione 26 and its organotin(iv) complex exhibit two absorption bands at 256 and 318 nm assigned to the 7t-7t and n-jt transitions of the C=N chromophore, respectively <2006SAA148>. These bands undergo a hyperchromic shift upon complexation supporting the participation of the C=N group in the coordination. 

The double helix can be denatured by heating (melting). Denatured DNA, like denatured protein, loses its structure, and the two strands separate. Melting of DNA is accompanied by an increase in the absorbance of UV light with a wavelength of 260 nm. This is termed hyperchromicity and can by used to observe DNA denaturation. DNA denaturation is reversible. When cooled under appropriate conditions, the two strands find each other, pair correctly, and reform the double helix. This is termed annealing. 

Increasing the number of conjugated double bonds leads to a marked bathochromic shift and to a hyperchromic effect, as predicted by Woodward s and Fieser s rules8. 

Chronic exposure of both rats and mice resulted in tubular nephropathy in both males and females. In rats, lesions were present in 45-66% of the males when they were sacrificed at 110 weeks after receiving 212 and 423 mg/kg/day hexachloroethane for 66 weeks of a 78-week exposure period (NTP 1977 Weisburger 1977). The renal lesions were characterized by hyperchromic regenerative epithelium, necrosis, interstitial nephritis, fibrosis, focal pyelonephritis, tubular ectasis, and hyaline casts. Lesions were also present in females but had a lower incidence (18% and 59%) for the two dose groups. Two-year exposures of male rats to much lower doses (10 and 20 mg/kg/day) resulted in similar effects on the kidneys (NTP 1989). Minimal to mild nephropathy was present in females for doses of 80 and 160 mg/kg/day. Over 90% of the male and female mice exposed to 590 and 1,179 mg/kg/day hexachloroethane for 78 weeks displayed tubular nephropathy when sacrificed at 90 weeks (NTP 1977 Weisburger 1977). Regenerative tubular epithelium was visible and degeneration of the tubular epithelium occurred at the junction of the cortex and the medulla. Hyaline casts were present in the tubules, and fibrosis, calcium deposition, and inflammatory cells were noted in the kidney tissues. 

The marked changes in the carbonyl IR bands accompanying the solvent variation from tetrahydrofuran to MeCN coincide with the pronounced differences in colour of the solutions. For example, the charge-transfer salt Q+ Co(CO)F is coloured intensely violet in tetrahydrofuran but imperceptibly orange in MeCN at the same concentration. The quantitative effects of such a solvatochromism are indicated by (a) the shifts in the absorption maxima and (b) the diminution in the absorbances at ACT. The concomitant bathochromic shift and hyperchromic increase in the charge-transfer bands follow the sizeable decrease in solvent polarity from acetonitrile to tetrahydrofuran as evaluated by the dielectric constants D = 37.5 and 7.6, respectively (Reichardt, 1988). The same but even more pronounced trend is apparent in passing from butyronitrile, dichloromethane to diethyl ether with D = 26, 9.1 and 4.3, respectively. The marked variation in ACT with solvent polarity parallels the behaviour of the carbonyl IR bands vide supra), and the solvatochromism is thus readily ascribed to the same displacement of the CIP equilibrium (13) and its associated charge-transfer band. As such, the reversible equilibrium between CIP and SSIP is described by (14), where the dissociation constant Kcip applies to a... 

Shifts in absorption spectra due to the effect of substitution or a change in environment (e.g. solvent) will be discussed in Chapter 3, together with the effects on emission spectra. Note that a shift to longer wavelengths is called a bathochromic shift (informally referred to as a red-shift). A shift to shorter wavelengths is called a hypsochromic shift (informally referred to as a blue-shift). An increase in the molar absorption coefficient is called the hyperchromic effect, whereas the opposite is the hypochromic effect. 

Weak coupling leads to minor alterations of the absorption spectrum (hypo-chromism or hyperchromism, Davidov splitting of certain vibronic bands). 

The compound was dissolved in solvents that has various polarity. The optimum conditions for concentration were investigated with respect to maximum absorption. Increasing concentration as 10 , 10, 10 M was lost spectral fine stracture when there was hyperchromic effect in absorption spectra. Optimal conditions were chosen as 1.5 x 10 M, since this gives the highest absorbance value. The solutions of the compounds were prepared daily in 10 M of MeOH, CHCI, THF, DMF and DMSO. 

Denaturation can be detected by the increase in absorbance of a DNA solution at a wavelength of 260 nm. This increase is known as the hyperchromic effect. 

In group I, the following were observed megakaryocyte size reduction, basophilic cytoplasm, reduced and hyperchromic nuclei which are signs of suppressed proliferation. In group II, the cell and nuclei are big with a distinct nucleolus showing increased proliferative activity of the lymphoid tissue (Fig. 11). 

Cell multiplication is inhibited because DNA synthesis is insufficient. This occurs in deficiencies of vitamin Bu or folic acid (macrocytic hyperchromic anemia). 2. Hemoglobin synthesis is impaired. This situation arises in iron deficiency, since Fe + is a constituent of hemoglobin (microcytic hypochromic anemia). 

Figure 24 shows the bathochromic and hyperchromic shifts of the of DNA on addition of increasing rj quantities of NjPjAzg to the medium. These effects... 

N3PjA2 and N P AZg, which exhibit significant activity against either L1210 and P388 leukemias or B16 melanoma, induce a noticeable fluorescence decrease and bathochromic and hyperchromic shifts ... 

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